Impatiens Necrotic Spot Virus
Impatiens necrotic spot virus (INSV) affects ornamental greenhouse crops like impatiens and mums but also many vegetables and herbs. The virus can infect over 200 plant species. It is a lethal virus spread by thrips feeding. Managing INSV is critical because it can easily over run your crop and cause you long-term problems. Thrips become infected with the virus while feeding as larvae. After they pupate thrips spread the virus to new plants when they feed as adults.
Thus, INSV management starts with thrips management. The essence is to start with sanitation. Thrips can feed on hundreds of plants so any weeds growing in or near your greenhouse can support thrips feeding and egg laying. Get rid of pet plants and mother plants. Maybe you or you grandmother want to overwinter last years peppers or begonias but don’t. Its not worth it. These can serve as reservoirs for thrips and virus and keep your house constantly infected.
If you have INSV in the greenhouse get rid of all plants that show symptoms and consider getting rid of all plants with thrips damage. Plants do not immediately show symptoms but they can still infect thrips. So even if you get rid of plants with visible INSV spots thrips may continue to get infected from asymptomatic plants and spread the virus. Manage thrips with insecticide applications or ramp up an existing biological control program to get thrips under control. Keep an eye out for tell tale rings and spots on leaves so you can keep ahead of this virus and of course monitor for thrips with sticky cards to keep ahead of them.
If you would like to see thrips defend themselves from predatory mites by butt slappin’ them watch the video.