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.