Despite efforts to keep it contained, tomato yellow leaf curl virus (TYLCV) has recently been identified in more nurseries and fields.

“There have been three new confirmed finds,” says Eric Natwick, Imperial County farm advisor. “It was found in tomato transplants in a retail store in El Centro, a nursery in Thermal, and in a commercial tomato field near Niland.”

TYLCV, a whitefly-vectored virus disease, is threatening peppers and tomatoes in the country. It is the most destructive whitefly-transmitted virus disease of tomatoes worldwide.

“TYLCV is transmitted by adult silverleaf whiteflies and can spread rapidly,” Natwick says. “However, it is not seed-borne or transmitted mechanically. It is difficult to identify just by looking at plants, because other viruses often cause similar symptoms.”

The first line of defense is to use only virus-free and whitefly-free tomato and pepper transplants, he says. After transplanting, various chemical control options can help keep whitefly populations suppressed in order to help prevent spread of the disease.

UC recommendations call for treatment of transplants in the greenhouse at least seven days before shipping. All stages of whiteflies should be targeted, including adults, nymphs, and eggs. After transplanting, a neonicotinoid insecticide should be used as a soil application or through a drip system to maintain control of whiteflies.

“After the efficacy of the neonicotinoid insecticide application begins to decline, the secondary spread of whiteflies will need to be controlled with other classes of chemistry,” Natwick says. “Continue to monitor whitefly populations throughout the season and treat when populations are present.”