Most spread occurs at warmer times of year, which is when the thrips populations tend to build up. Only the larval stage of the thrips life cycle can acquire the virus, while only the adults transmit it. Thrips larvae must feed on an infected plant for 20 to 30 minutes to become carriers. Yellowing and necrotic spots on leaves. Only a few thrips are needed to effectively transmit virus throughout a crop, well below the number of thrips needed to cause significant feeding damage.
Alternate hosts occur among cultivated and wild plant species.
These act as sources for spread by thrips to susceptible plants. TSWV is not transmitted through pollen or seed. Symptomless hosts cannot be rogued out of a crop and thus act as a source for virus spread. Thrips management is important. Only a few thrips are needed to spread the two viruses.