Tomato yellow leaf curl

About

A whitefly-spread virus that can nearly wipe out a tomato crop when young plants catch it. It is a problem mainly where winters are mild enough for whiteflies to live year-round.

Also called tomato yellow leaf curl virus, TYLCV, yellow leaf curl, tomato yellow leaf curl disease, TYLCD

How to recognize it

Symptoms

New leaves turn yellow along the edges and cup upward, and later leaves come in small and crumpled. Plants stay short and bushy with stubby stems, and flowers drop, so plants infected young may set no fruit at all.

Often confused with

Nutrient shortages, drought, aphids and other viruses can each cause one of these symptoms, so look for two or more together. Peppers can carry the virus without showing it.

Worse when

Warm climates with no real winter, lots of whiteflies, and tomatoes or weed hosts growing year-round nearby.

How it spreads

Whiteflies pick up the virus in 15 to 30 minutes of feeding and can pass it on for about 10 to 12 days; it also travels long distances in infected transplants and survives between crops in weeds like nightshade and jimsonweed. It does not live in soil or on stakes and is not spread by hands or pruning.

When

Whenever whiteflies are active; symptoms show 2 to 3 weeks after infection.

Where

Worst in warm, frost-free areas such as Florida, Georgia and Texas; it reached California in 2007.

What to do, gentlest first

Prevention works best; most sprays only protect healthy leaves and can't cure infected ones. Always read and follow the product label.

1. Plant resistant tomatoes Prevent

   Clemson lists Champion II, Charger and Margo hybrids, and Georgia trials found Grand Marshall, Jolene and Camaro held up well. Look for TYLCV resistance (Ty genes) on the label.

   Resistant plants can still get some disease.

2. Clean transplants and weed control Prevent

   Buy whitefly-free transplants, keep nightshade and other weeds down, and pull every susceptible plant at season's end so the virus has nothing to bridge on.

3. Bag and remove infected plants By hand

   Slip a plastic bag over a plant with early symptoms, tie it at the base, cut the stem below it, and let it sit a day or two before trashing. This traps the whiteflies on it.

   Don't just yank sick plants or toss them on the compost; that shakes off virus-carrying whiteflies.

4. Reflective mulch and fine row cover Barrier

   Silver reflective mulch cuts whitefly feeding, and fine-mesh row cover keeps them off young plants.

5. Oil, soap, neem or pyrethrin for whiteflies Organic spray

   Clemson suggests a weekly dilute horticultural or canola oil spray to discourage whitefly feeding. UF/IFAS lists azadirachtin (neem), pyrethrin and insecticidal soap, rotating products and covering leaf undersides.

   Sprays slow whiteflies but don't cure infected plants. Spray in the evening, away from bees, and follow the label.

Plants it affects

Green beans (snap beans), Pepper (sweet and chili), Tomato