| The wheat curl mite (WCM, Aceria tosichella Keifer), a pest of corn, is suggested to be associated with kernel streaking in corn (KSC). KSC is a physiological disorder that seriously affects the quality of food grade corn, but little is known about the factor/factors causing the expression of KSC or the dispersal characteristics of WCM into corn from winter wheat. These projects were conducted from 1999 to 2002 at Ridgetown College and the University of Guelph, Ontario, Canada, to study the dispersal characteristics of WCM from their source into corn fields, and the effects of WCM, low temperature during grain filling phase of corn, and sunlight and corn genotype on the expression of KSC. Corn fields adjacent to winter wheat, soybean or grasses were chosen to clarify the main source of WCM. Corn fields with wheat to the north, east, south and west were selected to study the critical distances for WCM dispersal in corn fields and the dispersal period of WCM. The influence of WCM, cool nights during the grain filling phase of corn, stronger sunlight on kernels when without husk protection, and corn hybrids on the expression of KSC was studied. The main source of WCM in corn in the summer was winter wheat; the critical distances to isolation planting of corn were 90 m when wheat was to the west of corn and 60 m when wheat was in the north or south; WCM dispersal started in late June, peaked in the first three weeks of July and stopped when winter wheat was harvested; The presence of WCM, cool night temperatures and intensity of sunlight were factors that influenced the incidence and severity of KSC, but their effects largely depended on the susceptibility of corn hybrids. Therefore, plant breeding may be a more logical approach to managing KRS in food grade corn. |
