Greenbug Nonpreference for Bloomless Sorghum 1

Greenbugs [ Schizaphis graminum (Rondani)] attack sorghum plants [ Sorghum bicolor (L.) Moench] every year, causing damage and reduced yields. Bloomless sorghum (lack of white, waxy exudate on leaf sheath) is a nonpreferred host to greenbug biotype C. The purpose of this research was to determine the age at which bloomless and sparse‐bloom sorghum plants become nonpreferred hosts to greenbug biotype C. Greenbugs were counted on near‐isogenic pairs of lines over a period of several weeks. Data from 2 yr indicated that bloomless plants 4 weeks old were nonpreferred hosts by the greenbug. It was concluded that bloomless plants 4 weeks of age could protect themselves and reduce the need for chemical control. Sparse‐bloom plants 4 weeks old were less preferred hosts than normal bloom sorghum plants, and probably could not protect themselves as well as bloomless plants.