Virus-Infected thrips may already be present in your greenhouse. Common reservoir plants for INSV include stephanotis, Swedish ivy, cyclamen and especially weeds in and around the greenhouse. Thrips cannot transmit the virus unless they acquire INSV as first-instar larvae. Winged adult thrips are primarily responsible for INSV spread. An infected thrips is able to transmit tospoviruses to at least one plant per day until its death.
Symptoms are very diverse and vary depending upon the cultivar, crop, time of year and temperature.
Generic symptoms of INSV include brown or black spots on the leaves and yellow, black or necrotic ringspots. Stunting, wilting, stem cankers and tip dieback can also occur. Sometimes, a mosaic, line or oak leaf pattern can occur on leaves, stems or flowers. After an infected thrips feeds on a plant, symptoms may appear in as little as two days up to several months. For example, cyclamen does not show any symptoms until two months after an infected thrips feeds on it.