Corn Viruses and Thrips

June 16, 2000
Concerns over the potential for corn-virus transmission from the southwestern part of the state have been sprinkling in over the last 2 weeks. It is not surprising virus infection is on the minds of people in the southern part of the state given the devastating effect viruses such as wheat streak mosaic (WSMV) had on the wheat crop this year. What does that have to do with the corn? Well, several reports have come in concerning thrips infestations in seedling corn. This is a bit of an unusual situation, with one consultant reporting 36 thrips per plant. The corn in these fields were of course showing the rasping from the thrips feeding but also appeared to be somewhat stunted. Stunting is a very common symptom of virus infection. So the question was this: Can thrips transmit viruses to field corn? Well, as it turns out, two viruses are reported to be transmitted to corn by thrips: maize chlorotic mottle and tobacco streak virus. The good news is that neither of these viruses has to date been reported in Illinois. The cautionary news is that virus diseases and their vectors don't have a map showing the state border so they know that they aren't supposed to show up there. We have seen time and time again that it isn't wise to ignore pest situations in nearby states. That's a bit more information about one of these diseases that bears keeping in mind over the next few years.--Suzanne Bissonnette

Author: Suzanne Bissonnette