CHOOSE TOMATOES THAT ARE RESISTANT TO TOMATO SPOTTED WILT VIRUS
Thereís good and bad news for those of us that enjoying growing (and eating!) homegrown tomatoes. Bad news first: Tomato Spotted Wilt Virus (TSWV) and bacterial wilt continue to devastate tomato plants in the South. Good News: Tomato plants resistant to TSWV are easy to find across North Florida.
The varieties of tomatoes that home gardeners commonly grow here are likely to be resistant to such common diseases as Fusarium, Alternaria and Verticillium, but not bacterial wilt or Tomato Spotted Wilt Virus.
Plant breeders have been working to develop new disease-resistant varieties. While they have not had great success with the bacterial wilt problem, they have developed outstanding tomato cultivars that are more resistant to Tomato Spotted Wilt Virus.
One of the new varieties resistant to TSWV is called Amelia. Commercial growers in Florida are having good success with this new cultivar. The fruit is large (8 oz), uniform, red, firm and aromatic. I grew Amelia tomatoes last season and was very pleased with the fruit.
Here are the varieties of TSWV-resistant tomatoes that I am familiar with: Amelia, Bella Rossa Hybrid, BHN 440, BHN 640, Fletcher, and Talladega. This year I am growing Bella Rossa, Fletcher and Talladega. Most will be available locally; seeds are available on the Web.
Here are my tips for healthy, tasty tomatoes:
-- Grow only disease-resistant, determinate tomato plants. Determinate tomato varieties generally reach a fixed height and ripen all their fruit in a short period of time.
-- Grow your tomato plants in containers using a high quality potting mix (not soil). I prefer to grow them in a self-watering container such as an EarthBox. It keeps plants evenly watered and makes nutrients readily available, both keys to producing a vigorous plant and better flavored tomato. Also, it protects your plants from nematodes and saves water.
-- Add calcium to the upper half of the potting mix or use a fertilizer that has at least 4% calcium added (I use ground up eggshells or a bit of dolomite or garden lime. Calcium nitrate also works but be careful not to over do it).
-- To insure that your tomato plants can take up the calcium, choose a fertilizer that uses a nitrate form of nitrogen. Ammonium nitrogen should be only a minor component because excess ammonium ions reduce calcium uptake. This leads to blossom-end rot as well as poor tasting tomatoes.
-- Keep plants evenly moist. Donít let them dry out.
-- Use a Bt product (such as Thuricide or Dipel) when you see signs of tomato worms. Repeat in 10 days. This natural insecticide is produced by the bacterium Bacillus thuringiensis (called "Bt") that has been used for decades by organic farmers to control crop-eating insects and by the World Health Organization to kill mosquitoes without using dangerous chemical pesticides.
-- Try a natural product, something using a pyrethrin as the active ingredient, for other insects. Pyrethrins are natural insecticides produced by certain species of the chrysanthemum plant. Liquid Rotenone/Pyrethrin is a good one that also includes rotenone as an active ingredient. Rotenone is an odorless chemical that is used as a broad-spectrum insecticide and pesticide. It occurs naturally in the roots and stems of several plants such as the jicama vine plant.
-- Use a liquid copper-based fungicide, or biofungicide, as a preventative for disease. Be careful not to burn the leaves of your plants with the copper-based fungicide. I have great success with Soap Shield and Plant Guardian biofungicides from Gardens Alive.
If you chose to grow tomatoes in the ground, you can increase their flavor by using similar techniques.
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