Mistletoe

Question: Can you tell me about the harmful properties of mistletoe and whether or not it is poisonous to people?

Answer: Mistletoe is an interesting group of plants with an interesting history. On a worldwide basis mistletoe may generically refer to any of more than 200 species of semi-parasitic shrubs found worldwide. However, according to Curtis J. Hansen, Curator Freeman Herbarium, Auburn University there is primarily only one species of mistletoe that dominates the eastern United States and that is the “Oak Mistletoe”, or scientifically speaking, Phoradendron leucarpum. It sounds very romantic in Greek but literally means "tree thief". Maybe that’s where the idea of “stealing” a kiss under the mistletoe originated.

All mistletoes are parasitic, meaning they grow into a host tree and "steal" nutrients for growth. However, they are also green, so they can produce some of their own nutrients through photosynthesis. While most mistletoes don't outright kill their tree-host, they can weaken them over time and ultimately be the cause of tree death. As the name indicates, Oak Mistletoe is found mostly in oak trees, but may also be found in other hardwoods. This particular species isn't known to grow in pines or conifers in our area. Mistletoes are particularly easy to spot at this time of year when the leaves of the hardwood trees have fallen. In fact, you may find many plants in full fruit with little white berries, for female plants and male plants that are in full flower. There are separate female and male plants within this species.

The parasitic properties of mistletoe are often duplicated by the men I see hovering around the sprigs at Christmas parties. Rather than true roots, the plant has extensions called holdfasts that grip the host plant. With the holdfast the plants take what they want from the host plant (again not unlike the aforementioned men).

In the South, tiny yellow flowers bloom on the evergreen mistletoe from fall into winter. The familiar white berries begin to form soon after pollination and resemble little packets of glue around tiny indigestible seeds. Although eating mistletoe berries may potentially be lethal for humans, birds seem to be immune to any toxicity.

The immunity of birds to mistletoe's poisonous qualities is essential to the welfare of the plant. The dispersal and propagation of mistletoe is largely dependent on birds that eat berries but do not digest the seeds. Studies suggest that seeds are most likely to survive and grow if a bird deposits them on the same species of tree on which the parent plant lived.
The use of mistletoe as a romantic lure stems from England at least as early as the 1500s. A version of the tradition persists today in secular Christmas decorations. Mistletoe has an interesting story behind its name. Several hundred years ago, it was thought that the mistletoe plant was formed spontaneously from bird droppings. Of course no one thought to look inside the bird droppings for a concealed seed. However, due to this error, the plant was given the name mistletoe which translates literally in English to “dung-on-a-twig.” I think we should stick with the name mistletoe because “meet me under the dung-on-a-twig” just doesn’t set the right festive mood.

Choose a Christmas Tree

Question: I love to use a real Christmas tree but the needles are always a mess. What type tree has the least problem with needle shedding?

Answer: The quick answer is "the fresher the tree, the better it will hold its needles." The only way to know you have a freshly cut tree is to cut it yourself, or in my case, I just point to the tree and tell one of my sons to cut it for me. If you buy a tree from a local "choose and cut farm," it probably doesn’t matter what species you purchase. The key to keeping the needles attached is to get the fresh cut tree stump into water as quickly as possible.

Choosing a pre-cut tree from a sales lot can be a little riskier than cutting the tree yourself, but if you follow these tips your chance of getting a good tree will improve greatly. Purchase a tree as soon as trees are available even if you don’t plan to decorate it for several days. The sooner you can get the tree in water the longer it will last. Most of the trees on sales lots were cut at the same time, so the longer they stay on the lot without water, the less likely the y will even take water up when they are placed in home tree stands with water reservoirs. Look at the tree trunk near the base and if you see splitting, the tree most likely has dried so severely it will not absorb water.

Look for a tree with a healthy, green appearance and few dead or browning needles. Run your hand along a branch to see if needles seem fresh and flexible. Needles should definitely not pull free easily. If possible, bump the base of the tree on the ground. You should expect some of the old dead needles to fall off, but if green needles also fall off, the tree is not very fresh.

Once you have chosen that perfect tree and have arrived back home safely, you should make a fresh cut a couple inches above the original cut. This removes any clogged wood that would prevent water uptake. If you are not ready to place the tree indoors you may store in a shady area outdoors or in an unheated room or basement. Regardless of where you locate the tree, make sure to check the water reservoir frequently and keep it filled a couple inches or more above the tree’s base. I have not seen any research that proves any concoction added to the water works significantly better than plain tap water.

Another tip to consider involves tree location in the home. Keeping the tree away from heat sources such as air ducts, wood stoves, and fireplaces will prolong the freshness and reduce the risk of fire. Make certain all lights and extension cords are in good working order and turn lights off when the tree is not attended. Because our homes are much drier in the winter when the heating system is operating, a small room humidifier can be good for you, your house plants and Christmas tree.

Some trees are just naturally better at retaining their needles. Douglas fir, Eastern White Pine, Fraser fir, Leyland Cypress, Scotch pine and Virginia pine are considered to have excellent needle retention. Freshness, however, is the key to needle retention.
If you would like some additional tips and a list of the pros and cons of the most popular species, click here.

Winterizing Warm Season Grasses is a No No

Question: The lawn care company recently applied an application of “winterizer” fertilizer to my Bermuda grass. Do you recommend winterizer fertilizer on warm season grasses?

Answer: If this is a well established lawn it is doubtful you need a fall application of fertilizer unless a soil test indicated a low level of potassium. Unfortunately, there are many products on the market sold as winterizer fertilizer. Cool season grasses such as fescue do most of their growing in the fall and spring and they need nitrogen to grow. However, many of these products are also used on warm season grass. Fall nitrogen application can be damaging to warm season grasses. Instead of increasing the cold hardiness, the opposite effect results. A warm fall will lead to continued vegetative growth which sets the plants up for cold damage. Check with your lawn care company and ask for the analysis of the fertilizer used. If the first number is 5% or below, it probably won’t hurt but it would be better if no nitrogen is applied to Bermuda and other warm season grasses after August.

I would suggest you have your soil tested to see if you need potassium or not. If you fertilize during the summer months it is very doubtful extra potassium in the fall will provide any benefit. However, if you do apply fall fertilizer, always apply it onto dry foliage to reduce the likelihood of salt burn.

A soil test provides a wealth of information and can be done for only $7 in Alabama and many state Extension offices offer similar services. Fall is a great time to test the soil because the lab is not as busy and if you need lime you have time to get it out on the lawn before spring growth starts. The lime will slowly move into the soil with winter rains and the pH will gradually rise in time for the first spring growth spurt. Once you receive your test results you may want to contact your local Extension office to talk with a horticulturist about your test results.
I have seen many test results that indicated an excessively high level of phosphorus and potassium. Phosphorus does not leach from the soil very quickly and it can build up to the point that no phosphorus will be needed for many years. Potassium can become so high that it interferes with the uptake of other elements such as magnesium and can result in a lighter green turf color. Also, be aware that an excessively high rate of potassium fertilizer can cause foliar burn.

Fall Is For Planting

Question: I am planning on planting some trees and shrubs this fall and would appreciate some planting tips to insure success.

Answer: Most of the time I get questions after newly planted trees and shrubs start to die, but I much prefer offering pre-planting advice to avoid problems.

Fall is the best time to plant most perennial plants including trees and shrubs and even most herbaceous perennials. The keys to success start even before planting perennials in the ground. It is always advisable to do a little research on the front end. There are some important questions you should answer before planting anything. One, are the plants I have in mind adapted to our climate? And I don’t mean adapted just to cold, but also to heat which is often as important as cold in our area. Two, will the plants tolerate the drainage within my soil? Poor drainage causes more plant death in heavy clay soils than drought does. Third, is the site chosen adequate for continued growth of the chosen plants? You should always think about the mature size when choosing the planting location and plant material.

The actual planting process will determine in large part the future growth and possibly whether or not a plant survives at all. There are at least two myths about planting woody plants that reduce your chance of success.

The first myth is that you should amend the planting hole with loose organic matter. If you have a lot of clay in your soil you should not use any organic soil amendments. There are several potential problems with adding organic matter and they all revolve around water. If organic matter is added to a hole surrounded by heavy clay soil, the water movement is drastically altered. You will have one of two problems. Either the water will not move out of the hole after rainfall, causing a bathtub effect, or the organic matter will dry and not re-wet well. Both of these scenarios will lead to root death. Plant wilting is not a good indicator of whether the soil is too wet or too dry because drought and excessive water both cause wilt.

The second myth is that you should not disturb the root ball coming out of the container. This myth relates to the previous myth, but needs some further explanation. Most plants are grown in containers at the nursery in a very light ground pine bark mix. This mix is great for growing shrubs and trees in the nursery but can present terrible problems in the landscape. If this loose bark is allowed to remain intact, the water movement issues described above still apply, with the added problem of air pocket development around the roots as the bark decomposes. Therefore, it is best to gently wash most of the loose bark material off the plant until it is, for all practical purposes, a bare root plant. This may involve pulling the roots out if they have started winding around the root ball. If necessary you can prune or slice these roots to help make this job easier, but try to leave as many roots intact as possible.

The planting hole should be shallow and wide. The depth only needs to be as deep as the root ball, but the hole should be two to three times the width of the longest lateral roots. Look for the uppermost lateral root to determine the planting depth. This lateral root should be at grade or slightly above the surrounding soil grade. Make a small ring of raised soil to hold water near where the outermost roots extend. Keep this area moist at all times for the first several weeks and then gradually decrease watering frequency and increase watering depth to encourage deeper rooting. Mulching the root area can give you a false sense of security about whether the plant has adequate water. It is very important to check the root area frequently to avoid drying. Do not apply mulch more than a couple inches thick.

A couple other post plant care tips are to keep the area around trees and shrubs weed and grass free, widening the weed free area as the plant grows. Also, avoid using weed whackers or mowers near the plant base.

Sweet Tea Olive

Fall is a great time to visit the Birmingham Botanical Gardens for many reasons but the fragrance coming from sweet tea olives is highest on my list. Tea olives are in the plant Genus Osmanthus which comes from the Greek and means “fragrant (osma) flower (anthus)” and it certainly lives up to the name. Tea olive, as the name indicates, belongs to the Olive Family (Oleaceae) along with numerous jasmines which are also very fragrant. The usually white blooms are small and not extremely showy and I am not surprised you could not tell where the fragrance originated. Even though individual blooms are small some cultivars have clusters large enough to add some floral interest. Tea olives are very nice evergreen shrubs with holly like foliage. You can easily tell the two apart even when not in bloom by looking at the leaf arrangement. Hollies have leaves arranged alternately down the stem and tea olives have an opposite arrangement.

There is a large planting of Osmanthus x fortunei 'Fruitlandii' at the BBG that makes a wonderful screen planting that is a pleasure to walk near. The mature height of tea olives may vary from six to thirty feet depending on the species and cultivar. I lived in Mobile in the past where the “fragrant tea olive” Osmanthus fragrans was the most commonly planted species. It is less cold tolerant but will survive in central (possibly north) Alabama in a protected micro-climate. It would be best to locate this plant on the south or southwest side of a structure. Much like camellias the main risk from cold is the rapid freezing and thawing action that is worse with a morning sun exposure. As the name seems to indicate it is the most fragrant of all the tea olives and therefore may be worth the risk of occasional cold damage. It also has the longest bloom period with blooms possible in every month with the letter “R” included.

In general all the tea olives will grow in full sun to part shade but in the central southeastern United States I would suggest a site with a break from the afternoon sun. Once established they are fairly drought tolerant but it may take a couple years to become established. Fall is a great time to plant and will require less care than spring or summer plantings. Choose a well drained area with slightly acidic soil for best results.

Tea olives are really quite easy to care for once established and have very few pest problems. If pest problems do occur it is probably due to stress from poor soil conditions or drought. Scale insects may flare up from time to time but can be controlled with horticultural oil sprays. Minimal pruning is needed unless they get too large. If you do prune them do so in the late winter to avoid removing the flower buds which form on the new growth each spring and summer. The exception to this rule would be the Delavay tea olive (Osmanthus delavayi) and our native Devilwood (Osmanthus americanus) which bloom in the spring and should be pruned just after blooming like other spring blooming plants.

Devilwood is the only native tea olive and is native to swamps and stream banks in the southern US including south Alabama. The name comes from the extremely hard wood which is a “devil” to split and work. The leaves are larger and less holly like than other tea olives. Like other tea olives the flowers are quite fragrant but they occur in early spring on last year’s growth. This native plant is more tolerant of wet soil conditions but is adaptable to most Alabama soils. It would be a great choice for a rain garden because it tolerates frequent flooding and can take the drier times between rain events.

Regardless of which tea olive you plant you are sure to be enchanted by the sweet aroma they produce and yes they can be used in tea.

Pruning Encore Azaleas

Many people ask how to prune Encore Azaleas and a picture is worth a 1000 words - so take a look.

Wooly Bugger of a Problem

Question: There is a tree in our yard that has rough warty bark and makes a small fruit about the size of a cherry. The problem is it is dripping a sticky substance on everything underneath its limbs. Do you have any idea what tree this is and what might be the problem?

Answer: The tree is probably a native hackberry or sugarberry tree, but the fuzzy white pest causing the sticky mess is not native. The pest is called the Asian Wooly Hackberry aphid and was first detected in North America on hackberry trees in Georgia in 1996 and in Alabama in 1998. It is not a severe problem every year, but it appears to be a problem this year. The aphid appears to be restricted to native hackberries or their relatives. Although the trees seem to survive the pest flair ups fine, the aphids produce large quantities of the sticky substance called honeydew. As you observed, this creates a sticky mess and promotes the growth of black sooty mold on leaves and on surfaces beneath infested trees. In August and September it can look like a mini snow storm near these trees because the aphids look like cotton fuzz balls. Although this tree is a very tough tree for urban environments, the honeydew can be an annoying problem in residential and business districts where the tree may be used to shade parking lots, walkways or patios.

Some municipalities out west have been treating all hackberry trees in parks and parkway strips with a systemic insecticide called imidacloprid, which is an effective, but relatively expensive insecticide. Researchers at the University of California have had good results with this insecticide even with rates as low as one eighth of the label recommendations. Since it is a fairly expensive product you might try these lower rates and just provide adequate water to make certain what you apply is not wasted. Imidacloprid can provide season long control and can be applied during the growing season after you notice an early infestation in the spring. Treatments are applied as a systemic insecticide, meaning that the product is taken up by the roots of the plant and spreads through all the tissues of the plant. The material may be mixed in a bucket of water and poured around the trunk. It is too late to treat trees now and it won’t be long before the leaves fall off anyway. Just to play it safe don’t use this product near edible plants since it is taken up by plant roots.

The fruit is a favorite fall treat of many birds and other wildlife. This is another reason to use the lowest possible effective rate of insecticides so that the pesticide will be out of the plant by fruiting time. Since there is no research to tell us if the chemical is totally gone by harvest time, I would suggest you avoid eating the fruit.

I talked with the director of the Plant Diagnostic Lab here at the Hanna Environmental Center, Dr. Jim Jacobi and he said “the wooly hackberry aphid does not cause appreciable damage to tree health but from time to time can be quite a nuisance. I would not plant this tree in an area near a parking area or patio, but it can still be used as a specimen tree in a natural area or at the fringes of your property where it won’t cause a mess and can still provide food for wildlife and act as a host plant for at least three species of butterflies that develop on the foliage.”
For more information visit the following web address: http://msucares.com/ and search for Wooly Hackberry Aphid. A great detailed article will be the first link that pops up.

Central South Native Plant Conference

Birmingham Botanical Gardens will host the Central South Native Plant Conference at which I have a small speaking part.

Every three years gardeners, landscape architects, and plant enthusiasts of all kinds are treated to one of the most extensive seminars in the nation, the Central South Native Plant Conference. The symposium, whose theme is “Tough Native Habitats”, will be hosted by Birmingham Botanical Gardens October 17 and 18.

Held about every 3 years since 1989, the conference “is a place for people to learn and to share their knowledge about our regional biological heritage” says program chair Jan Midgley. The focus of the weekend is native plants that call Alabama home. Birmingham Botanical Gardens plays host the 2008 conference, whose goal is to foster awareness, appreciation and increased usage of plants native to the Southeast.

Highlights include an outstanding line up of Southeastern native (and invasive) plant experts in a variety of lectures, break-out sessions, field trips and tours. From novice to expert, everyone is welcome but you need to pre-register. The complete program and registration information is available at www.bbgardens.org . You may also contact Shelly Busby, Special Events Coordinator at Birmingham Botanical Gardens for tickets or with any questions by calling her at 205-414-3965.

Ant Invasion

Question: My house is being invaded by ants. We do not leave food stuff or dirty dishes out so what is causing this ant explosion?

Answer: When outdoor temperatures get hotter and conditions get drier ant problems get markedly worse. The ants are most likely Argentine ants but during an extreme drought fire ants may also come indoors. Both travel in trails into kitchens, offices and bathrooms searching for food and/or water. Even if you are super clean they may come indoors in search of water.
Argentine ants which are small, just 1/8 inch long are very consistent in size. They are native to South America. They were accidentally introduced into the United States more than 100 years ago in New Orleans coffee shipments. Fire ants are likewise South American natives and came in sometime later through Mobile Alabama. Fire ants will often be quite variable in size from 1/16 inch to 1/4 inch long, they have reddish brown bodies and black abdomens and they also bite!
Entomologists say you can reduce your chances of having ants in your home but even the cleanest homes may become infested. To discourage them, rinse all drink cans before placing them into the garbage or recycling bin and empty garbage containers often. And, don't leave any food or drinks out for any length of time. Argentine ants love sugar and will show up to dine on it, literally by the thousands, overnight.
For Argentine ants most experts don't recommend using contact insect killers. These products may make you feel better because you can watch the suckers die in real time but you'll never get rid of them all. For long term controls of both types of ants you have to kill the queen or queens. For Argentine ants the ant bait stations or gels work the best. They don’t give you that immediate satisfaction of a contact killer but the results are much longer lasting.
If you have fire ants the control should involve a little more effort in finding the source. Treating outside will help control ants foraging inside from outdoor colonies. Although unlikely it is possible the ants are nesting in a wall. In this case, a contact insecticide should be used at the nest source and it may require assistance from a professional pest control operator to locate the nest. More likely, the fire ants are in an outdoor mound and foraging for food or water indoors. You might say they live in the suburbs and commute in to work. If you decide to treat indoors make sure the product you select is labeled for use indoors. Read and follow the directions on the product label for best results. Be sure to keep products away from children and pets. Again, eliminating the outdoor colonies will be critical to ridding your home of this menacing pest.

For more information visit the newest nationwide Extension website: www.extension.org and check out the fire ant portion of the site. This site has a wealth of information that you can trust has been well researched and is very up to date.

Spurweed is a Pain (click title for audio file)

Most of the time homeowners view weeds as a nuisance in lawns, but for most, these plants only cause ‘mental anguish’ – not physical. Well, spurweed (also called lawn burrweed) is a lawn pest well known throughout the warmer-climates of the south for its potential to inflict genuine physical pain to people and pets. Dr. Jeff Derr, Extension Weed Specialist at Virginia Tech, has indicated that spurweed is increasing in importance as a serious lawn weed every year throughout Virginia’s Tidewater region, and it has long been noted as a serious pest in the our area of the deep south here in Alabama.
This winter annual broadleaf plant has opposite leaves that are twice divided into very narrow lobes. It looks a lot like parsley in appearance but if you have any questions regarding its identification, you probably want to contact your local extension office for assistance.
Spurweed becomes a major problem in the landscape in mid-late spring when it flowers and sets fruit that are surrounded by razor sharp spines. It is a nuisance to pets, with the sharp spines potentially getting lodged into their paws. And all it will take is one step on this weed by someone walking across the lawn either in bare feet or loose fitting sandals to quickly identify that the weed is present— everyone will know from the shriek of pain! Of course, spurweed on athletic fields is even of more concern for athletes that might be doing a lot of sliding or tackling as part of normal play in spring sports.
There is little that can (or should) be done about spurweed after it has flowered and produced its troublesome spines. If you have it, anticipate that it will be producing plenty of seed to support next year's population and make a note on your calendar for the next fall to treat IF you identify it in the turf. Spurweed can be controlled by an application of many fall preemergent herbicides applied in September. Field research trials have shown excellent results in the fall pre-emergent applications of isoxaben, sold as Gallery and Green Light Portrait. This chemical is specific to broadleaf weed control, making it a compatible chemical for most for fall lawn seeding programs. You can also control spurweed quite easily with most two and three-way phenoxy broadleaf post-emergent herbicides (products containing 2,4-D, dicamba, MCPP or MCPA etc.) if you treat the weed while it is young and actively growing in the fall or early winter.
This is one of the pests that causes much more concern than just a disruption of turf uniformity and appearance-- it is a pest that actually inflicts physical pain if not managed appropriately.

Originally prepared by Mike Goatley, Virginia Tech with some modification by Tony Glover, Alabama Cooperative Extension System

June Bugs (click for audio file)

Question: My yard has been invaded by green bugs that are about twice the size of Japanese beetles. They buzz around my kids and pets and I am concerned about one of them being bitten or stung.
Answer: The pest is likely a June beetle or as I called them growing up, a June bug. Green June beetles are velvet green with orange or rust stripes along the outer margins of the wing covers. Beetles can range from ½ to 1 inch in length and as you described, they are twice as large as their more destructive relative, the Japanese beetle. Peak flights for this insect started in late June and will continue another couple weeks.
The adults out buzzing around in your yard are probably seeking a mate or there is a good food source that they are attracted to. The adults primarily feed on over ripe fruit but sometimes they feed on leaves of things like peach trees. Since they do have chewing mouthparts it may be possible to be bitten by them but more than likely if you feel something like a bite it is from their spiny legs and they don’t have a stinger. Even though they seem aggressive while buzzing around and I have been scared out of my wits when disturbing a group of them while picking peaches or blackberries I have never been bitten by them.
They will soon complete their lifecycle and lay eggs for a new generation. The eggs will develop into a grub that will develop and overwinter in the soil. These grubs are different from most grub species in the southeast in that they come out of the ground at night and move from one place to another. Even more unusual they crawl on their backs when moving. One of my kids used to do that as an infant so it may not be as unusual as I think. When disturbed the grubs curl up into a C-shape, much like my teenage girls do when I ask them to wash the dishes.
The adults can cause damage to the turf while nesting but it is normally not severe enough to treat with an insecticide. The grubs can actually be beneficial in the turf because small populations of them will aerate the soil while tunneling. However, large populations can cause excessive tunneling causing the grass roots to dry out and die in patches. If control of grubs appears warranted do so in August and September when the grubs are small, close to the surface and more susceptible to pesticides. Most recommended pesticides work best after an irrigation or a soaking rain.
I am not sure how wide spread this problem is in recent years because we get so many more calls about the dreaded Japanese beetle which causes much more damage to ornamental plants. Normally I don’t pay a lot of attention to what one or two folks say about pest numbers but if one of the people is your mother you better listen. In this case while visiting my mother in Cullman Alabama recently she asked me, “do you know, where have all the June bugs gone?” to which I responded, “No – but if you hum a few bars I may be able to pick it up”. After I picked myself up and brushed off a little I asked her what she meant and she swears she has not seen any June bugs since the Japanese beetles arrived a few years back. I would be interested to know if anyone else has observed a decline in June beetles around your home in the last few years. Send me an email with your observations to satisfy my mother’s curiosity. You may drop me a note or a question at gloveta@aces.edu . For more information and control options visit our web site at http://www.aces.edu/ and go to the publications area. We have two relevant publications you may want to read: “Biology and Control of the Green June Beetle” and “Controlling White Grubs on Lawns and Turf”.

Tomato Wilting

Question: Some of my tomato plants have wilted and died quickly and I noticed a white powdery substance on the base of the stem - any ideas?

Answer: The description you gave is very typical of "southern blight", also known as white mold and stem rot, and it is caused by the soil-borne fungus Sclerotium rolfsii. We have had numerous reports about this disease in the last few days. The disease is a common problem on vegetables, especially tomatoes, as well as most other broadleaf crops such as pepper, eggplant and beans. Plants of any age can be attacked if environmental conditions are suitable. Development of southern blight is favored by moist conditions and high temperatures (more than 85 degrees F).
Generally, the first above-ground symptoms are leaf yellowing and wilting of infected plants. The stem at the soil line often appears soft and sunken (cankered) and develops a brown to black discoloration both internally and externally. Under moist conditions, a white fungal growth can be seen on the lower stem near the soil surface; on fruit in contact with the soil; and on crop debris on the soil around the base of the plant. Spherical, light brown, mustard-seed size ( 1 to 2 mm) objects called sclerotia often form in the mycelium. Under dry conditions, fungal mycelium and sclerotia may not be visible. However, if southern blight is suspected, placing a section of the lower stem and a moistened paper towel in an enclosed plastic bag for 24 hours will stimulate formation of a white mat of fungal growth. This would be diagnostic for southern blight.

The fungus is spread as mycelium in infested organic matter or as sclerotia in infested soil. Infection usually takes place at the soil surface but may also occur below the soil line. The fungus may spread more than 3 feet through the soil and from plant to plant within a row. It is common to see five or six infected plants within a row killed. Sclerotia, produced on crop debris and dying plants, serve as inoculum for the next crop.

Control of southern blight is difficult to achieve when inoculum levels are high and environmental conditions favor its development. Rotations with crops such as corn, and grain sorghum will reduce disease. Rotations are most effective when tomatoes or other susceptible crops are not planted in the same area more than once every 3 to 4 years.

Deep-plowing the soil to bury crop debris and the fungus will also help reduce inoculum. Wider plant spacing to improve air movement and roguing infected plants will aid in reducing disease development and spread within a field. Adding copious amounts of organic matter may help as well. The information for this blog camer from the Alabama Cooperative Extension System - Tomato Wilt Disease publication.

Okra Problems

Question: Why is my okra growing so slow this year and making so few fruit?

Answer: In the mid to deep south this has been an unusually cool spring (dang global warming - you never know how it will manifest itself ;) ). Okra is a heat loving plant that simply will not grow when the soil or the air temperature is cool. It is a hibiscus and cotton relative that loves the heat. Interestingly, the blooms are only open for a day and if not pollinated they will shrivel up and fall off without forming a pod.

Be patient and keep the plants watered and actively growing and when the weather really heats up and its too hot to be in the garden they will be bearing when other vegetables have bit the dust.

For a little more information and interesting history visit this UGA site.

Oak leaf blister

Question: Why would oak leaves start falling off the tree in the late spring or early summer?

Answer: Check the leaves closely for small spots that are often cup shaped. Some of these spots appear grayish while others are green, but all are characterized by small puckered areas. If this is what you are seeing it is likely a fungal disease called oak leaf blister. This particular disease affects many species of oaks and is a problem whenever our spring is wet and cool late into the season. Although it has been hot over the last month think back to early spring and you may recall we had a cool wet spring (in the mid-south US). Although infection took place much earlier you may only now be seeing leaf drop. On the plus side even heavy infestations are not a cause for concern.

Some of the infected leaves will not fall from the tree until the normal leaf drop period in early fall. When conditions are right and infected old leaves are preparing to drop for the winter, they will produce spores that infect the developing buds that will form the new spring leaves next year. This is the way the cycle repeats itself each year. If weather conditions are not right for infection next year you may not even see the disease. Again, the disease does not pose a serious threat to tree health so there is no need to spray with a pesticide. For information on other possible oak tree pest click here.

Mystery Muscadine

Last week I had what I thought was an easy question that forced me to dig deeper than I normally would have. A lady called with a question about her muscadine plant that she relocated to an arbor three years ago and she has never gotten any fruit off of it. I assumed she had a female flower type and no perfect flowered variety nearby. Typically you will find nurseries selling varieties that are either female or perfect flowered types. If you plant a female type alone you will not have fruit but many of the female varieties have desirable fruit. Therefore, they are planted with perfect flowered forms nearby to provide pollination.

This lady really wanted to know for sure so I asked her to bring a bloom sample in to get a closer look. After looking at the sample it was apparent she did not have a female variety as I originally assumed but a male plant that is totally incapable of fruiting (see photo above). Male plants are not uncommon in the wild but what really confused me was she said the plant was dug from an abandoned vineyard on her property. Why would anyone plant a male plant I wondered when a perfect flowered plant would produce pollen and fruit? When she told me the vineyard (she believed) had been planted in the 1940's that gave me a critical clue.

I pulled out an old textbook from my college days and found out that until 1948 there were no perfect flowered varieties available and growers were forced to plant male plants to act as pollinators for the female varieties. This lady had the bad luck of moving a male plant which were usually planted at a 1 to 8 ratio in these old vineyards. Of course in the wild you still find plenty of these male plants but they probably only exist in very old vineyards planted before perfect flowered forms became available.

Tomato Problems

Question: This year I decided to grow my own heirloom tomatoes because they are so expensive in the store but the lower leaves are dying and the problem is moving up the plant. Can you tell me what is going on and how can I stop the plant from dying? Also, I have heard a lot about tomatoes and salmonella lately – should I be concerned about my garden tomatoes?

Answer: Now you know why heirloom tomatoes are so expensive. Most of them have little or no disease resistance and they tend to make a lot of foliage compared to the amount of fruit produced. This is another reason for their expense plus a possible reason for increased disease. The large amount of foliage means the foliage stays wet longer after rain and dew. Wet foliage means increased foliar diseases like “early blight” which is the likely culprit on your plants. The relatively cool wet weather earlier this spring made for perfect conditions to spread early blight. Click here for other disease possibilites: http://www.aces.edu/pubs/docs/A/ANR-0895/

Early blight is the most common and widespread foliar disease on tomatoes in the southeast. If not controlled, this disease can severely damage fruit quality and lower yields. On young plants, dark brown, irregular spots form and completely encircle the stem, causing plants to quickly wither and die. On older plants like yours, the spots are restricted to one side of the stem. Leaf spots, which typically occur first on older leaves, begin as small (1/l6 to 1/8 inch in diameter), dark, irregular spots and enlarge to form larger spots up to ½ inch in diameter. Tissue surrounding these spots often will turn yellow, resulting in early defoliation. On severely infected plants, fruit may become sunscalded because of the lack of foliage for protection.
Once the disease becomes severe on individual plants control is unlikely. Removing infected leaves from the garden can help. Other cultural controls for this disease include; mulch to prevent soil splashing onto lower leaves, proper fertilization, don’t wet the foliage when watering, stake or cage the plants and prune off side shoots. Fungicides are also available and do a good job preventing disease but they don’t cure disease.
Let me elaborate on a couple of the cultural control options. Nitrogen fertilizer is a good thing for plants like tomatoes that grow fast but excessive fertility leads to growth that is often more susceptible to pest. There is a fine line between enough and too much fertilizer. If your plants are dark green and growing very fast you may have crossed the line. Along a related path you might want to prune excess growth off by removing side shoots called suckers. These suckers grow from the main shoot at an angle from leaf attachment points. In general they are less fruitful and the thick growth that results is more prone to disease because it is vigorous and causes the plant to dry slower after a rain or dew.
I have a couple thoughts about your salmonella question. First, salmonella is not a disease that tomatoes can contract but a contamination that can happen during harvest and/or packing. Second, it is possible to have salmonella contaminate even your garden tomatoes. As a precaution you should never apply fresh animal manure to the soil surface when vegetables are in the garden. Always compost animal manures well or till them into the soil before planting. Consider using a mulch around plants to reduce the risk of animal fecal matter splashing onto tomato fruit and other vegetables. Tomatoes that are home grown or vine ripened locally are very unlikely to pose a serious health risk. Nevertheless, even your own garden vegetables should be handled with clean hands and washed thoroughly before eating. You should take the same precautions you expect your favorite restaurants chef to take when handling vegetables to be eaten raw.

Squishy Squash

Question: My yellow summer squash is doing weird things this spring. Some are shriveling up on the ends, some have a fuzzy black growth on the ends, and others are just not growing but seem to get darker and tougher skins.

Answer: Congratulations, you have hit the squash problem jackpot or the squash disorder "perfect storm". In this case there are multiple reasons for the multiple problems. Let me take them in order:

First, poor pollination will cause poorly formed fruit and/or fruit end shriveling. Also, the dreaded calcium defeciency can cause similar symptoms as well. Cool soils can contributue to the lack of root growth and the lack of the plants ability to pick up the calcium.

Second, Choanephora fruit rot is favored by wet weather. Both blossoms and fruit are affected and fruit nearest the ground are more likely to become diseased. It is not unusual to find 30-40% of blossoms and/or fruit infected with the fungus. The growth looks like the picture above (from the The American Phytopathological Society website). On the plus side this disease is seldom long lived and will pass when weather conditions change.

Third, the very cool weather this spring (especially at night) has greatly slowed fruit enlargement and has led to slow growing fruit which matures (hence the darker color and tougher skin) without very much fruit enlargement. Pollination also affects fruit size and could be a contributing factor.

Warmer and drier weather will solve all the problems discussed and no treatments are needed.

Rhododendron Deadheading

I was out in the Birmingham Botanical Gardens admiring the last of the rhododendron blooms. The long and cooler than normal weather this spring has given us a long azalea and rhododendron bloom period. I think it is possible that the stress of last year may have also contributed to a big bloom show this spring. The plants looked stressed but they were filled with blooms. Sometimes when plants are under stress they will make a lot of bloom buds as a last ditch effort to reproduce itself. One way to reduce stress and to funnel energy into new growth is to dead-head old blooms. While out in the gardens we shot some video showing this task. Take a look here to see how this process is carried out.

The case of the missing tomato leaves.

One of my co-workers, David Hubbard had a question from a client who wanted to know what could have completely defoliated 36 tomato plants in a two night period. The damage was described as tomato stems and main branches remaining with no leaves or evidence left. My response was I felt it was too early for tomato hornworms or some other kind of caterpillar and it was likely a four legged rather than a six legged critter. (diagram from NCSU publication)

The client re-planted and decided to watch the garden the first night. He went out with a flash light and observed some bugs on the foliage. He treated the tomatoes with sevin dust and the next morning found large numbers of dead bugs at the base of the plants. He brought the bugs in for me to identify and they turned out to be vegetable weevils.

The interesting thing was the that these critters had never been a problem for this seasoned gardener of 30 years. When we discussed his recent gardening activities he reaveled one minor change in his normal modus operandi. Because of the drought of 2007 he had planted a large number of collards and turnips near his back porch where the water hose was available. Normally his greens were planted far away from his home. He recently destroyed the left over winter greens by tilling and then immediately planted tomato seedlings to the area. Upon investigation I noted that these greens were the host plants for the vegetable weevil larvae. My guess is when they became active the only food available were these tiny tomato plants and they completely stripped the foliage in short order.

The moral of the story is be careful to not jump to conclusion without a thorough investigation.

Stalk Borer

Every now and then (actually more frequently than I want to admit) I am totally stumped by a question. For example this morning I got a call from a gardener with a new garden spot (this was an important clue) whose tomatoes were dying one by one. She had done some good investigative work on her own and found a small larvae in the stem near the base of the plant. I asked Jim Jacobi, from our plant diagnostic lab and he was briefly stumped but came up with a possibility.

(PICTURE AT RIGHT FROM NCSU - IPM LINK BELOW)

After further investigation I agree with him that the likely culprit is the "Stalk Borer" (Papaipema nebris). As mentioned, the "new garden" comment was an important clue. Apparently this insect is mainly a pest in either "no-till" or recently tilled areas (previously in weeds or grass). According to the information linked above stalk borers tunnel in almost any large stemmed plant. Their host range encompasses at least 44 families and 176 species of plants. Some cultivated crops subject to infestation include corn, cotton, potato, tomato, alfalfa, rye, barley, pepper, spinach, beet, and sugarbeet. Although many weedy plants are infested, giant ragweed is preferred.

On the plus side this is not a serious pest on most garden sites. Tomatoes are not a favorite food source but happen to be the only thing nearby where they overwintered. Pesticides that could be used for control would be those that kill other larval species (check here for products) but I doubt this would be a serious recurring pest.

Arsenic and old ferns

Question: I have removed an old deck in an area where I want to plant a vegetable garden. I have been told there are unsafe materials that could have leached into the soil from the treated wood. What suggestions do you have to remedy this situation?

Answer: On February 12, 2002, the Environmental Protection Agency (EPA) announced a voluntary decision by the wood preserving industry to phase out the use of wood preservatives that contain arsenic for any wood products destined for consumer use. This affects virtually all residential uses of wood treated with chromated copper arsenate, also known as CCA, including wood used in play structures, decks, picnic tables, landscaping timbers, residential fencing, patios, and walkways. The EPA has not concluded that there is unreasonable risk to the public from CCA lumber, but believes that any reduction in exposure to arsenic is desirable.
Despite this assurance there is still some concern amongst vegetable gardeners and those who have small children who might play in (or eat) the soil that is contaminated. It can be very expensive to have soil tested by a private lab but Auburn University offers this service for a modest fee of $15 per sample. They can test for chromium, copper and arsenic if you request it on the soil test form available at any Extension office in the state. The normal soil test for plant nutrients cost only $7, so make certain you request this special test.
In a gardening situation, exposure to these elements can only occur if they move from the treated wood into soil or compost that is in contact with the wood, then are taken up by plants, and finally are ingested by humans who eat those plants. This is known as an “exposure pathway”. Low concentrations of arsenic, chromium, and copper occur naturally in water, soil, plants, and the human body. Copper and possibly chromium is essential for plant nutrition, and all three of these metals are essential for human and animal nutrition. That means humans must always have small amounts of these elements present in their diets. Although there are rare instances of dietary deficiencies of these elements, most normal diets supply adequate levels of each. Intake of excessive amounts, however, can have adverse effects on plants and humans.
Also on the positive side both copper and chromium are held very tightly to soil particles of clay and organic matter when the soil pH is maintained around 6.5 on the pH scale. This is also the best pH for vegetable growth. Unfortunately, arsenic is much more mobile within the soil and can be taken up into the plant roots and leaves. In general, most metals remain in the roots, with limited movement to edible portions above the ground. There are exceptions, of course: leafy green vegetables such as lettuce, spinach, and mustard greens tend to move arsenic from roots to leaves. In general, however, the greatest human consumption of metals results from eating root crops such as beets, turnips, carrots, and potatoes. In these crops, most of the metals remain in the surface skin and can be removed by peeling.
The ability of some plants to help take bad things out of the soil is called phytoremediation and a sun tolerant fern called brake fern has been found that has a remarkable ability to remove arsenic. The arsenic accumulates in the foliage and would require the gardener to remove the foliage and dispose of it off site or they are just recycling the arsenic. If you want to read the low down on this remarkable fern visit: http://www.malibuwater.com/Phyto.html and for further tips on gardening in contaminated soil visit: http://npic.orst.edu/ or call them at 1-800-858-7378. A company has a patented phytoremediating fern by the name of “edenfern” that you can purchase and find online with a simple web search.

Note: Photo from Stanford University photo collections

Ink Berry Holly

I recently talked with a Master Gardener trainee in North Alabama about her long row of Inkberry Holly that were dying one by one. She had brought a small sample of a dead stem for me to look at and I agreed it was dead. It is very hard to do a complete autopsy with a six inch sample of a large shrub. It is kind of like asking the CSI team to look at an ear and determine the cause of death of a person. I asked her to go home and dig up an entire plant so I could look at the root system.

Inkberry Holly (Ilex glabra) is native to the United States and is the only holly that spreads by underground runners. This bit of information would be helpful in the diagnosis. They are tall, multi-branched and evergreen. This holly can reach heights of 6 to 12 feet and widths of 8 to 10 feet. Inkberry holly is very adaptable to poor soils and is tolerant of extreme temperatures. It can often be found growing wild in the wetland areas of south Alabama although it is fairly drought tolerant. Inkberry holly is very pest resistant so I did not suspect an insect or disease. It is hardy in Zones 4 to 9. The leaves are a lustrous, dark green, and the fruit is typically black. This holly has many desirable features and makes a great screen plant which is the way it was being used in this case.

When she came back with a plant sample something jumped out (not literally) right away and I hope you can see it in the picture above. The plants were about 10 years old and had done fine until the year of the drought (2007). They started dying from the top of the hill and were making their way down (dying one by one). Even though the plants are fairly drought tolerant I suspected drought but I did not expect to see what I did. If you look closely you will see a layer of landscape fabric and a mass of roots above the fabric. This stolen producing plant had developed most of it's root system in the mulch layer that had increased year by year. The mulch had partially decayed creating a very good environment for roots (plenty of air and moisture) as long as moisture was plentiful. However, the extreme drought exposed the weakness of roots growing in mulch.

Mulch is great when used correctly and in moderation. If a landscape fabric is used the mulch must be removed when fresh mulch is added to avoid this problem. This same problem can develop without landscape fabric when mulch is used to excess (2-3 inches is plenty). When Dr. Jacobi at the Plant Diagnostic lab looked closely he saw few roots in the soil and almost all the roots above the fabric.

I thought this was very interesting and it may come up again after or during a dry year.

Slime Flux on Oak

Question: My oak tree is “weeping” awful smelling ooze down the trunk on one side. Insects and bees are constantly hovering around the ooze. What is it and will it harm my tree?

Answer: What you are describing is a fairly common occurrence on trees and it is called “wet wood” or, my favorite, “slime flux”. I am not sure who came up with a great name like “slime flux” but you have to admit it has a ring to it. It occurs in apple, birch, elm, hemlock, maple, mulberry, oak, poplar, willow and many other trees. Slime flux is very common in large, mature, landscape oaks, tulip poplar and elms.

Slime flux is a bacterial disease. The infected wood is frequently discolored or appears water soaked hence the name “wet wood”. Carbon dioxide gas is produced during fermentation by bacteria. The gas produces pressure in the wood. This pressure forces sap from the trunk through cracks in the trunk. This oozing of sap is termed fluxing. The flux is colorless to tan at first but darkens upon exposure to the air. As fluxing continues, large areas of the bark become soaked. Many different microorganisms grow in the flux producing a foul or alcoholic smell. As you mentioned, various types of insects are attracted to the slime flux. Did you notice if the bees and insects could fly in a straight line after feeding on the ooze?

Now I will address your original question about the health of your tree. If the fluxing continues for months on a branch rather than the main trunk, leaves on affected branches may be stunted and chlorotic. Grass may be killed where the flux runs down the trunk onto the grass. If as you described the ooze is from the main trunk the sap may continue to ooze for months, with no apparent damage to the tree. This slime flux may be triggered by heat, drought and other stress. Last years drought stress will likely cause a great increase in this problem this year and possibly next year.

There is no curative or preventive measures for slime flux except to maintain trees in a general good state of vigor and minimize wounds and injuries. In other words keep lawn mowers and weed eaters away from tree trunks. An insignificant nick in the trunk can lead to problems far down the road in terms of overall tree health. Treatment is not advised because more damage can be done to the tree in attempting to cure slime flux than the slime flux will do alone. It has been a common practice with slime flux to drill a hole in the trunk and insert a pipe, which does not cure the problem. Inserting a pipe only allows the sap to drip on the ground rather than run down the trunk. This practice is not recommended because it does not speed up the natural healing process. If there is loose or dead bark in the slime flux area, remove all of the loose bark and allow the area to dry. Do not apply a wound dressing.

The next time you are visiting with your neighbor across the backyard fence ask him if he has seen any slime flux lately. I am sure that will start an interesting conversation. For more information visit: http://www.ces.ncsu.edu/depts/pp/notes/oldnotes/od8.html where much of the information for this article came.

Winter Honeysuckle

Native versus non-native plants. I don't know why but I have thought for as long as I can remember that Lonicera fragrantissima (winter honeysuckle) was a native plant (to North America) but it is native to China (I think). I have heard for some time that this plant is on some groups watch list as a potential invasive plant. Despite the fact that its not native and may be invasive I sure would miss this wonderfully fragrant plant. It greets me every winter day from December til April as I walk up to the front door of my workplace (the Birmingham Botanical Gardens).

I know it is extremely drought tolerant because I had some in some gallon pots that I forgot about. They went uncared for and unwatered for two years. When I found them they had no potting soil left in the pot - just a mass of roots. I planted them last year before the worst drought in my lifetime and watered them once. I looked at them today and they look great (maybe this is why they are thought to be potentially invasive).

Fig Propagation

Question: I have a wonderful fig tree in my yard that I want to take with me when I move but it is much too large to move – any suggestions?

Answer: Figs are easy to propagate because they root very easily. There are several ways to propagate them. The most common method is to root cuttings taken in late winter or early spring so now is a great time.

Take cuttings about 6 inches long and pencil to finger thick. If the weather is still unsettled and frost is likely, store the cuttings in a sealed zippered bag in the produce bin in your refrigerator. However, if the weather is warm and likely to stay warm, pot your cuttings. Place a half sheet of newspaper tightly into the bottom of a 4 or 6 inch-deep plastic pot. Put a little sand or a good-quality potting mix in the bottom of the pot, then stand one to four cuttings upright in the pot, and fill the pot the rest of the way with more sand or potting mix.

Water the pot thoroughly, and set it in a very bright but not a direct sun location. It should be warm--at least 70 degrees F. If you cannot keep the air temperature above 70, provide bottom heat to bring the soil temperature up. Cover the pot with an empty 2- or 3-liter soft drink bottle with the lid on and the bottom cut out. Do not water the cuttings again until they are very dry. Lift the pot occasionally to test for dryness. If the pot is very light, set it in a pan of water, and let it soak. When you see vigorous growth, it is time to harden off the new plants. Remove the bottle cap, and see how the plants do. If the plants look to be thriving after a few days, remove the bottle. If the plants begin to wilt, cover them again with the bottle.

After a few days, it will be time to pot up the new plants. Don't do this just because you see leaves growing. Sometimes there will be four or five leaves and few if any roots. Wait until you see vigorous growth. Pot the plants in individual plastic pots (1 gallon size), and apply a light application of liquid fertilizer. In 4 to 6 weeks, depending on the vigor of the variety and the weather, the plants will be ready either for a larger pot or for in-ground planting. When you plant them in the ground keep them well watered until they have rooted in very well. This usually takes one summer of careful attention. A 2 or 3 inch layer of mulch will help the new plants conserve moisture, keep the new roots cooler and provide cold protection in the winter.

Figs are a fun and easy fruit plant to grow in our area. They are cold sensitive to temperatures in the teens or below but will usually come back from the root if well established. They are interesting fruit because they do not require pollination at all to produce their delicious fruit. One plant is likely all you will need unless you want to make a winters supply of fig preserves. Because they produce fruit parthenocarpically (without pollination) they tend to fall off easily under stress. In our area the stress is usually a drought during fruit enlargement. You may want to place a soaker hose around the plant and give it a weekly soaking while the fruit are maturing.

For more information visit the following web sites: www.aces.edu/pubs/docs/A/ANR-1145/ or http://hgic.clemson.edu/factsheets/HGIC1353.htm

Mistletoe species in the Southeast U.S.

Question:
I read an article about mistletoe and I am doing a project for Organismal Biology and I was wondering if you could tell me where/how I can find out how many species and what species of mistletoe are located here in Auburn Alabama?

Answer:

That question is so simple I think I will let my driver answer it (just kidding). Here is the answer I got from Curtis J. Hansen, Curator Freeman Herbarium, Auburn University:

Yes, I'd be glad to answer that! There is primarily only one species of mistletoe that dominates the eastern United States and grows from New York to Florida and west to Arizona-- that is Oak Mistletoe, or scientifically speaking, Phoradendron leucarpum. There is only one other species in the southeastern US (east of Texas) called Mahogany Mistletoe that is found very rarely in Florida. The center of distribution (where the most diverse number of species are found) for mistletoe is western North America, from Canada in the north and down into the western US extending east to Texas. There are about 34 different species of mistletoe (from three different genera) found in the western US and Canada. In addition, there are 6 endemic (found only in a particular area) mistletoes found in Hawaii. Mistletoe species in the genus Arceuthobium, commonly called Dwarf Mistletoes, are pests and cause tremendous losses and reduced productivity in the timber industry in the western US.
All mistletoes are parasitic, meaning they grow their root systems into a host tree and "steal" nutrients for growth. However, they are also green, so they can produce some of their own nutrients through photosynthesis. While most mistletoes don't outright kill their tree-host, they can weaken them over time and ultimately be the cause of tree death. The genus found in our area, Phoradendron, means "tree thief" in Greek--an appropriate name for a parasitic plant.
As far as locating mistletoe in Auburn goes, it's pretty easy. All one has to do is go out side and scan the surrounding hardwood trees and you'll find clumps of greenish-looking "bushes" among tree branches. That's mistletoe. As the name indicates, Oak mistletoe is found mostly in oak trees, but may also be found in other hardwoods. This particular species isn't known to grow in pines or conifers in our area. Mistletoes are particularly easy to spot at this time of year (winter)when the leaves of the hardwood trees have fallen. In fact, you can still find many plants in full fruit with little white berries, for female plants and male plants that are in full flower, the flowers are very small. There are separate female and male plants in this species.

Herbs and Bees

A gardener asked the following question: “I want to include herbs in my garden and need to know more about requirements for growing them. I’m also interested in attracting pollinators, especially honeybees. Which herbs will provide food or habitat for them?”

Answer: With spring fast approaching, honeybee populations in decline, and herbs gaining status with a variety of gardeners, this is a very pertinent question.

I asked Sallie Lee, Jefferson County Extension Agent to respond, as she works with Jefferson County Beekeepers and is involved with an heirloom herb garden project in Birmingham.

She replied: “Tony, to simplify the question, let’s break the answer into two parts, one to address the herbs, one for the honeybees”.

Herbs have many attributes that contribute to their increasing popularity in gardens and landscapes. Their historic use, from primarily culinary and medicinal, to the 21st century has expanded the role of herbs. Today, we grow herbs (or “’erbs”) for aesthetic reasons, for use in cooking (culinary), as medicinal, aromatics, ornamentals, household/industrial, and wildlife habitat.

Herbs are considered one of the easiest groups of plants to grow, and once established, most are considered low maintenance; they do very well with little water or fertilizer.

Requirements for growing herbs, regardless of reason, need to be considered before planting them in the ground. And, while herbs are adaptable to a range of soil and growing conditions, most don’t do well in poorly drained soil. Another limiting factor is the amount of sun available to them; if the site receives less than 6-8 hours of sun a day, look for another site or consider herbs that can handle light shade.
The sun/shade factor is especially important for pollinators, including honeybees, since most of them are attracted to plants that flower in full sun conditions.

Another factor to consider is soil; heavy clay is a challenging environment for most herbs. Make their life easier and more productive by planting herbs in raised beds or amending existing soil with well-composted organic matter to improve its porosity.

Herbs are a solution to the need expressed by many beekeepers; to increase nectar availability in an area. Herbs are versatile, blooming the same year they’re planted in many cases. With sufficient variety, an herb garden can have plants in bloom 10 months of the year, providing nectar and pollen sources for honeybees. However, not all herbs attract honeybees, so gardeners should pay attention to variety. Herbs such as basil, bee balm, hyssop (anise), mints, sage, and thyme are examples of bee favorites.

Designing an herb garden is similar to other gardens; segregate tall growing plants such as bee balm from low spreading herbs like thyme to minimize unwanted shading.
Perennial herbs should be the focus of the garden as they will last for years without being replaced, although annuals can be used as fillers where appropriate.

Attracting wildlife, in this case a very special pollinator, takes a little extra work, but the effort is worth it when you see and hear the hum of honey bees visiting your herbs.

For additional information, pull up the following Alabama Cooperative Extension publication, “Growing Herbs”.

Bamboo Control

Question: How do I control run away bamboo in my yard?

Answer:
Bamboo is one of the most difficult invasive plants to control once established. The wrong type bamboo can take over landscapes, stream banks, and woodlands.

There are many species of bamboo sold in the nursery trade, some are more invasive than others. Creeping types are, as a rule, very invasive once established. There are clump-type bamboos that spread at a much slower rate. For most homeowners this is the most responsible choice. You may avoid control problems down the road and your neighbors won’t be so upset. These clump-type bamboos can be removed by digging up the offending plants. Unfortunately, some of the more popular types of bamboo sold in the nursery industry are the more invasive, spreading types. These plants spread by thick, tough, underground stems (rhizomes). The rhizomes are resilient to tough environmental conditions and most herbicides.

To control such aggressive plants you must eradicate or contain the entire infestation. Treating only a part of the infestation will be doomed to failure because bamboo can re-establish rapidly. Also, bamboo control programs will require an intensive control strategy over several years.

Containment of creeping types of bamboo is possible, because the rhizomes are typically fairly shallow (less than one foot deep in the soil), but difficult because they can grow over the top of barriers. Barriers made of concrete, metal, plastic, or pressure-treated wood should be installed at least 18 inches deep. Inspect the barrier once or twice a year and remove any rhizomes that are visible.

To control, start with physically removing as much of the rhizome and root mass as possible. It will be impossible to remove all pieces; therefore, follow-up treatment with herbicides will generally be required. Few herbicides are effective on bamboo. The only treatment regime that has been proven to work are winter applications of diclobenil(Casoron or Barrier) combined with summer spot sprays with glyphosate (Roundup). Diclobenil will kill many of the rhizomes and prevent others from re-establishing through early summer. After that time new sprouts will emerge and must be controlled to prevent re-establishment. Reapply glyphosate whenever new growth is present. It will take at least two years of this regime to get good control. In that time you will not be able to plant herbaceous ornamentals, hemlocks, or many other shrubs in that area because diclobenil can kill these ornamental species. If the bamboo is growing in plant beds where these herbicides cannot be used, remember bamboo is a grass and can be suppressed with selective grass controlling herbicides. Always check chemical labels to make certain the product can be used as you intend.

A non-chemical option is to put the entire infestation into turf for several years. Bamboo does not tolerate frequent mowing. Remember, regardless of which method of control you choose, an intensive effort over multiple years will be required to completely eradicate bamboo. Therefore, spend a little extra time researching which ornamental bamboos are best for your yard.

Much of the information in this blog came from an NC State article by Dr. Joseph C. Neal, Weed Scientist Department of Horticultural Science. You may also read another good publication on this subject from the University of Florida by Jason Ferrell, Mark Czarnota, and Ken Langeland (who took the picture above)

Stevia

Question: My new year’s resolution was to loose some weight and I have heard there is an herb that can be used as a sugar substitute. Since sweets are my weakness I am looking for a natural sugar substitute. Do you know what the name of this herb is and how can I grow my own sugar substitute?

Answer: There have been few botanical discoveries quite as dramatic as the realization that the leaves of a species of herb called, Stevia rebaudiana, are intensely sweet. Stevia plants are perennial plants native to Paraguay that include over 150 different species. However, this particular species is an anomaly, since none of the other species in this North and South American genus produce these sweet compounds at high concentrations. Stevia sometimes called “sweet leaf or candyleaf” is considered by the U.S. Food and Drug Administration to be an unapproved food additive. It is approved by the FDA only as a dietary supplement. There is conflicting research on the safety of this herb and you should research carefully before using any herbal product.
Because they are commercially unprofitable, relatively few highly sweet plant components have been developed as sugar substitutes. However, due to the interest in natural products, the discovery that this stevia plant has naturally occurring sweetness has attracted great interest. Stevia and stevioside, an extract of stevia, have a menthol-like, bitter aftertaste that limits their usefulness. However, they have been used for years as sweeteners in South America, Asia, Japan, China and some European countries.
For many centuries native Paraguayans have used stevia as a sweetener in herbal and medicinal teas. As mentioned, stevia cannot be sold and advertised as a sweetener but it is available as stevioside extract and can be purchased at most health food stores. The first thing to remember is that stevia is sweet but not exactly like sugar. All this sweetness comes from the leaves of a rather homely little plant that at maturity can be up to 18 inches tall and as wide. It’s a perennial herb that won’t tolerate freezing temperatures. Therefore, grow it as a houseplant or treat it as a tender annual that’s set out after all danger of frost is past. Bear in mind that temperatures can affect the sweetness. The stevia leaves will be sweeter as the temperatures increase throughout the summer.
Stevia is can be grown from seed, but is more easily rooted or it may be purchased as a small plant in the herb or perennial section of the garden center. Your small plants will start slow, much like a pepper plant or okra which requires hot weather to grow well. They need a good rich soil, full sun, warm air, and just enough water to keep the growing medium evenly moist. They’ll be quick to drown if you over water and equally quick to die if you let the soil dry out completely. If you are more interested in the sweet leaves you should remove the small white flowers that appear in summer. They are heavy users of nutrients and should be fertilized regularly or use a slow release fertilizer at planting. They may occasionally be attacked by aphids, mealy bugs, and spider mites, so keep an eye peeled. If you catch the pest early a strong stream of water may be all that is needed or use a little insecticidal soap as directed on the label.
Use stevia leaves fresh or dry them for storage by placing them in single layers between paper towels set in a warm place for a week or so or dry them in a dehydrator. Then use a spice grinder to reduce them to powder. It may not solve your sweet tooth problem but you are bound to burn a few calories while working in the garden.

Note: See this publication from which much of this information was derived. Thanks to Georgia Jones, Extension Food Specialist at the University of Nebraska.

Drip Irrigation

Question: I want to install a landscape at my new home but am very worried about the water shortage. What tips can you give to increase my chance of success?

Answer: The first suggestion would be to plant as soon as possible. In our area we can plant woody plants all winter if the ground is not frozen. The plant roots will start to grow and establish before the plant top growth occurs and before the stress of a hot summer.

Second, I would encourage you to consider using a low volume irrigation system. Low volume irrigation unlike sprinklers puts the water in a small area near the plant. Sprinklers are very wasteful because they water the entire surface area and much of the water either runs off or evaporates. Low volume methods work by placing emitters in a flexible tube near the base of newly planted trees and shrubs. (picture at right is from the University of Texas publication on "Low Volume Irrigation")

The primary design goal of a low volume system is to apply water to a uniform soil depth. Water is delivered at or below the surface of the planted area exactly where it is needed. For new landscapes the emitter should be placed directly over the edge of the root ball of the newly installed plants. This will keep the root ball moist while encouraging new roots to develop in the native soil. For larger plants you may need two or more emitters to insure the root ball maintains adequate moisture.

These systems are not difficult to install and remind me of playing with tinker toys as a kid. The most critical part of installation is making sure you reduce the pressure before the water enters the drip tubes and provide a screen filter in-line to avoid stopping up the small holes in the emitters. It is very important to periodically check the emitters to make sure they do not get stopped up. Unlike sprinklers which are highly visible you can’t really tell if emitters are working unless you inspect them while they are operating.

I have often been asked why can’t I just punch or drill a small hole in a water line near the plant rather than buying emitters. The answer is simple. These small holes would not distribute the water evenly, the water would come out too fast, and the hole would get larger over time. Emitters are designed to put out very slowly at rates from ½ to up to 2 gallons per hour. If your soil is a very heavy clay soil you would want a very low rate emitter and if it is sandy you could use the higher rates. If you use a high rate emitter on a heavy or hard soil the water will pool on the surface and run off the target area.

I know many municipalities tell their customers to do hand watering only during times of water shortages but low volume drip irrigation is even more water conserving then hand watering. Generally speaking when people do hand watering on new plants they water a larger area than necessary, water is applied too quickly causing runoff, and some water evaporates before reaching the ground. Also, who’s going to know if the water is on if it is below the surface. I am not encouraging wasteful use of water but I believe this is even more water conserving than hand watering and I would not feel the least bit guilty for using this method in lieu of hand watering. Just make sure you are using a timer so that the system only runs a prescribed amount of time. I made the mistake of leaving mine running without a timer several years ago and floated my plants out of the ground after a couple days. To learn more you may watch a short training video for gardeners at Texas Earth Kind web site and choose the "Low Volume Irrigation" tab.