Month: May 2018

2018 Tropical Storm Alberto

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Guest Post Written by Pam Knox,

Long-time residents of Georgia may remember the devastating floods of Tropical Storm Alberto in July 1994. The rain was so intense that Georgia’s one-day rainfall record was set during that storm, with 21.10 inches recorded at Americus for a 24-hour period ending on July 6, 1994, as the storm stalled over the state. In spite of that incredible record and the resulting damage, the National Hurricane Center did not retire the name of Alberto. This year, Alberto is the first name on the list of Atlantic tropical storm names for the season which begins on June 1.

The latest 5-day outlook for the Atlantic tropical region from the National Hurricane Center indicates that there is an 80% chance of this year’s Tropical Storm Alberto to develop in the Gulf of Mexico in the next five days, even before the season officially begins. While it is not likely to bring extreme winds and storm surge to the area, it is expected to bring copious rain to an area that has already received up to six times as much rain as usual in the last week, covering most of Georgia except the northwest corner. Another six inches is expected across a wide area of Georgia in the next seven days from the slowly moving storm. While this is not likely to be as wet as the 1994 TS Alberto, the wind and rainfall are still going to cause tremendous problems for us here in Georgia, along the coast and inland across most of the state.

Now is the time to think about what you need to do to get ready for the rain, whether or not it organizes enough to be designated as a named tropical storm. If you have weekend activities planned along the Gulf Coast for this Memorial Day weekend, be prepared for intermittent heavy rains, gusty winds, high waves and rip currents in the water along the coast from New Orleans to the west coast of Florida. If you are inland, prepare for localized flooding which will be worse because the ground is already saturated in many areas. Move equipment and livestock out of low-lying areas. Expect some trees to fall because of the wet soil conditions, even if the winds are not that strong. This may mean blockage of roads or disruptions in power, so check your generators now if you need supplemental electricity for your operations. If water covers the road, do as the National Weather Service recommends and “Turn Around, Don’t Drown.” You won’t be able to tell if the road has been undercut or washed away, and water has a tremendous potential to move cars and trucks even when only a few inches deep. The Extension Disaster Education Network (EDEN) has several useful publications on preparation and recovery at https://eden.lsu.edu/educate/resources.

I have heard from a number of contacts that the rain and cloudy conditions over the past two weeks has caused a lot of problems for producers, leading to splitting blueberries, increased fungal diseases, slow growth of crops, and the inability to get into the field to do side dressing of corn, application of fungicides and other treatments, and planting. Unfortunately, I don’t see a shift in this current pattern, and above average rainfall is likely to continue for the next several weeks, although there will be some drier periods that may allow you to get work done.

For updated information follow @SE_AgClimate or on Facebook at SEAgClimate. An excellent source of updated weather information is the local National Weather Service office, but you can also get information from many commercial vendors and the National Hurricane Center. Do not count on your smartphone weather apps to give you the most current information, since many of them are only updated once or twice a day. Keep monitoring for changing conditions, since above average sea surface temperatures in the Gulf of Mexico could lead to a rapid drop in pressure and increase in winds as the center of the storm gets closer to land, or the storm could move in a different direction under weak steering currents.

If you have comments to share about how the current rainy and cloudy weather is affecting your work and your crops, please feel free to send them to me at pknox@uga.edu. I always like to hear how the weather and climate are affecting Georgia agriculture.

Pam Knox
Interim Director, Georgia Weather Network
Crop and Soil Sciences, CAES

Tomato Hornworms and Parasitic Wasps

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Tomato hornworms (Manduca quinquemaculata) are a serious problem for tomato growers. These caterpillars have a large appetite and can quickly defoliate a tomato plant. If you find hornworms in your tomatoes, simply pick them off and drop them in soapy water. However, if you find a hornworm with white oblong obtrusions, leave it!

The white obtrusions are actually the cocoons of a parasitic wasp. A female wasp has laid her eggs under the skin of that hornworm. As the eggs hatch the larvae actually feed on the hornworm insides. The larvae eat their way out of the caterpillar and spin the cocoons you see. Eventually adult wasps will emerge from the cocoons and the weakened hornworm will die.

Photo credit: Texas A&M

The hope is that the emerging wasps will find other tomato hornworms to parasitize and you will have managed that pest. There are some generalist parasitic wasps that will provide that service for you. There is a braconid wasp, Cotesia congregates, that specifically looks for tomato hornworms. This small wasp has clear wings and as an adult they are nectar feeders. To persuade the wasps to stay in your garden you will need to have flowers. The small braconid wasps are attracted to small flowers like yarrow and small asters.

Instead of reaching for an insecticide for tomato hornworms encourage the ecosystem to assist you in managing that pest!

Happy Gardening!

Common Tomato Problems

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This important information is shared with us by Robert R Westerfield, College of Agricultural and Environmental Sciences, Extension Horticulturist. He is our vegetable guru.

The tomato is the most commonly-grown vegetable in America. Unfortunately, producing big, red, juicy tomatoes requires considerable effort in preventing and controlling diseases.

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Select tomato varieties that are disease resistant. This is very important! This may be your only chance to control certain diseases. The letters behind a variety’s name tell what diseases it is resistant to: T-Tobacco Mosaic Virus, V-Verticillium Wilt, F-Fusarium wilt and N-Nematodes, some good possibilities are Celebrity and Better bush but there are many others. Resistance does not mean the plants are immune to these diseases.

Move tomatoes away from where they or potatoes, eggplant or peppers were planted last year. Soils in these areas may harbor leftover diseases. Bury all plant debris when tilling and keep mulches pulled back an inch or two from the stem.

You can plant tomatoes in a traditional vegetable garden, a raised bed or put a few plants in a flower garden. I would avoid potted tomatoes because they require extra care in watering. If you grow potted tomatoes-use 5 gallon or larger pots. Water until water runs out the drain holes and then let the soil dry slightly before watering again.

The number one tomato disease now is Tomato Spotted Wilt Virus (TSWV). It is spread by thrips. Usually the top of the plant looks stunted or wilted. The young leaves may turn yellow and often have brown or black discoloration in them. The veins on the underside of leaves may thicken and turn purple. Fruit can have raised or flat rings or circles on them. Ripe fruit will have yellow circles or semicircles. The stem can have long brown lesions.

Once tomatoes get the disease, there is no control. There are two varieties of tomato that are resistant to TSWV. I have not yet seen them yet in stores. Spraying for thrips is also not effective.

Destroy infected plants as quickly as possible early in the season to prevent spread. Seal them up in a plastic bag. Even after the plant is pulled up thrips can leave it to spread the virus. Late in the season you may just want to let the infected plants finish ripening the fruit they have. Late season infection is less of a concern.

A fungus causes Fusarium wilt. It blocks the water conducting tissues in the plant. The leaves yellow and wilt, often starting at the bottom of the plant. This disease can affect just one side or one to several branches of the plant. The plant can die early producing no fruit. If you cut into the plant, the vascular system (just under the bark) will be brown. Control Fusarium wilt by planting resistant varieties. The ‘F’ after the name, like Celebrity VFN identifies these. Fusarium wilt can survive in the soil. Do not plant tomatoes in infected areas more than once every four years.

Bacterial wilt causes a rapid wilting and death of the plant. The plant dies so quickly it does not have time to yellow. To identify Bacterial wilt, cut through the stem. Bacterial wilt browns the pith or middle of the stem. On bad infections, the pith may be hollow. Cut a short section of the stem and suspend it in a clear glass of water. You can often see a milky ooze streaming out of the bottom of the cut stem. There are no controls or resistant varieties for bacterial wilt. It also attacks peppers, potatoes and eggplant. Carefully dig out infected plants and soil and discard. Do not plant any of these vegetables in this area for at least four years.
Southern blight is a white mold that rots the stem at or near the soil line. The plant then wilts or dies. Look for the cottony fungus growth and the light brown BB-sized fruiting structures of the fungus. The fungus may be slightly above or below the soil line. You may not see the fungus growing on infected plants when the weather is dry.

Bury all plant residues before planting, plant vegetables farther apart, and treat with Terraclor at planting if you have a problem with Southern blight. Some people wrap the stem near the soil line with foil to slow this disease and to control cutworms. The foil must extend two inches above and below the soil line.

Blossom-end rot (BER) appears as a dry leathery spot on the blossom end of tomatoes. It can also affect peppers and watermelons. The spot is usually on the blossom end, is tough and leathery and slightly sunken. Other rots may infect this spot. These fruits may turn red first.

BER is caused by lack of calcium in the blossom end of the fruit. By the time the tomato reaches the size of a nickel it has most of the calcium that it will ever have. This is why we need to prevent blossom end rot early. Inadequate water supply, low pH or low soil calcium levels can cause this problem. Find and correct these problems.

Once a plant has BER, it is hard to control. Calcium is best taken up by the roots so sprays are not very effective. Control and prevent BER by:

  • Water the plants well and let the soil dry between waterings. A sample watering schedule is three-quarter inch twice a week if there is no rain.
  • Apply a two to three inch mulch around the plant. Do not heavily prune the plant.
  • Soil sample and lime and fertilize as needed. Avoid large applications of high nitrogen fertilizers when fruit are small.
  • Add gypsum (calcium sulfate) or lime to the soil at planting. Mix a cup in each planting hole or use one pound per 100 square feet. You can apply this once you see the problem but these treatments work slowly. Plants often appear to grow out of the problem as conditions improve.

For further information. Tomatoes flowers will not set fruit if temperatures are not right, if the plant is water stressed or if it already has enough fruit. Night temperatures should be 55o to 75o F. for best fruiting. Night temperatures above 90o will especially cause problems. Water twice a week (3/4 inch each time) and mulch plants. There is a blossom set chemical you can spray if you can locate it in the garden centers.

Leaf Rolling occurs when the plant has set a heavy load of fruit and the light intensity is high. It can be caused by wet soils. The condition is harmless and should not hurt final production. Prune less heavily and plant in a well-drained area.

Uneven ripening occurs as grey or white spots inside the fruit. Several factors can be involved including improper nutrition, high temperature and disease. The only thing we can correct is nutrition. Do not use too much nitrogen and/or too little potassium. Soil sample and fertilize accordingly. Use high potassium fertilizers, 5-10-15, 15-0-15 especially as fruits begin to get larger than a quarter.

Fruit cracking is due to rapid growth after periods of slow growth. Rain after drought and heavy fertilization can cause fruit cracking. Harvest fruits after they begin to turn red but before they crack. Follow the watering practices we have discussed and look for cracking resistant varieties.

Catfacing is caused by cool temperatures at time of pollination. The fruit is deformed with ‘zippers’ on the skin. The fruit can have lobes, tear drops or several blossom scars. Plant resistant varieties, plant later, or use row covers to increase the temperature on cool days and nights. The large beefsteak varieties appear to be more susceptible. The fruit is still edible.

Sun scald appears as a white blistered area on the top of the tomato. Do not prune heavily and maintain nutrition and pest control so as to provide a good leafy cover for the fruits. Be careful not to confuse this with Blossom End Rot.

Resource(s): Vegetable Gardening in Georgia

Center Publication Number: 100

Happy Gardening!

Tomato Planting 1,2,3

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Now that you have chosen your tomato plants it is time to put them in the ground. There is a trick to planting tomatoes that helps them get through a long, dry, hot Georgia summer.

Snip off the lower leaves.
Snip off the lower leaves.

Step 1: Tomatoes need full sun, 8 hours, for setting fruit.  They also need well-drained, porous soil with a pH of about 6.2.  Plan on giving them at least 2 feet X 3 feet of growing space.  You will need to stake the plants or use wire cages to contain the plant growth.  Once you have your site ready, start with a healthy plant with a strong stem.  Notice the stem seems hairy.

Step 2:  Gently remove the lower leaves with snippers or by pinching them off with your fingers. Be careful not to make tears along the stem which would create wounds.  Leave the top two or three leaves.

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The hairs on the now buried stem will become roots creating a strong root system to better handle periods of drought.

Step 3:  Dig the hole deep enough so that you can bury the stem up to the remaining top leaves.  The part that is planted under the soil will develop roots creating a strong, deep root system that will help the plant better handle dry periods.

Press the soil around the plant so that a slight depression is formed for holding water.  These steps should get you one step closer to that BLT!

For more information about growing tomatoes see Robert Westerfield’s publication Georgia Home Grown Tomatoes.  For the best information for your area, contact your local UGA Extension Agent.

Happy Gardening!