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Title: EFFECT OF GREENBUGS ON WINTER WHEAT YIELD

Author
item Kindler, Dean - Dean
item Elliott, Norman - Norm
item GILES, KRISTOPHER - OKLAHOMA STATE UNIVERSITY
item ROYER, TOM - OKLAHOMA STATE UNIVERSITY
item FUENTES-GRANADOS, R - OKLAHOMA STATE UNIVERSITY
item TAO, F - OKLAHOMA STATE UNIVERSITY

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2001
Publication Date: 2/1/2002
Citation: KINDLER, D., ELLIOTT, N.C., GILES, K.L., ROYER, T.A., FUENTES-GRANADOS, R., TAO, F. EFFECT OF GREENBUGS ON WINTER WHEAT YIELD. 2002. JOURNAL OF ECONOMIC ENTOMOLOGY. V. 95. P. 89-95.

Interpretive Summary: Greenbugs can cause severe yield loss of winter wheat when their density reaches high levels. At present, the relationship between greenbug density and the amount of yield loss that will occur is poorly known. This lack of knowledge limits the ability to make accurate decisions concerning the economic benefits of using insecticides to control greenbug infestations in nwinter wheat fields. The effect of greenbugs on the yield of several winte wheat cultivars grown in Oklahoma was studied during four years. Our objectives were to determine the effect of different greenbug densities during autumn and spring on winter wheat yield, and to develop models to describe the effect of greenbugs on yield loss in autumn- and spring- infested wheat. Greenbug density in plots varied among years and among growing seasons within a year but were generally sufficient to cause reduced yield. Among yield components, the number of heads per square meter rand seeds per head were usually negatively related to greenbug density. Seed weight was rarely affected by greenbug density. A regression model estimated yield loss for greenbug-susceptible cultivars in relation to greenbug density. The model predicts a 0.51 kg per ha loss of yield for each greenbug that persists for one day per tiller in years with near normal precipitation, and a loss of 1.17 kg per ha under severe drought conditions. All greenbug-susceptible winter wheat cultivars exhibited similar yield loss in relation to greenbug density, suggesting that the regression model is robust for predicting yield loss for susceptible cultivars. The model will be useful for aiding growers and other crop managers in making economically correct decisions regarding the need to apply insecticides to their fields to control greenbugs.

Technical Abstract: The effect of greenbug feeding on the yield of the following winter wheat cultivars was studied: 'Karl', a recent derivative 'Karl-92', and '2163', all greenbug susceptible cultivars; and 'TAM-110', a cultivar with resistance to biotype E greenbugs. These cultivars are commonly grown in Oklahoma. Our objectives were to determine the effect of varying densities of greenbugs during autumn or spring on yield, and to develop mathematical models to describe the effect of greenbugs on yield loss in autumn- and spring-infested wheat. The intensity of greenbug infestations achieved in plots by artificial infestation varied among years and growing seasons within a year but were generally sufficient to cause a reduction in yield. Among yield components, the number of heads per square meter and seeds per head were usually negatively correlated with greenbug-days. Seed weight was rarely affected by greenbug infestation. A regression model estimated yield dloss for greenbug-susceptible cultivars in relation to the number greenbug days that accumulate per tiller at 0.51 kg ha*-1 loss of yield per greenbug-day in near normal years, and a loss of 1.17 kg ha*-1 under severe drought conditions. The three greenbug-susceptible winter wheat cultivars exhibited similar yield losses, as indicated by a common slope parameter, in relation to the intensity of greenbug infestation, suggesting that the model is robust for predicting yield loss for susceptible cultivars.