Cultural control of leafhopper-induced maize wallaby ear symptom in forage maize via early planting dates

Maize wallaby ear symptom (MWES) is induced by maize orange leafhopper (Cicadulina bipunctata) feeding and stunts the growth of maize. We examined the relationship between maize developmental stage and MWES occurrence and the effect of planting date on injury from MWES in western Japan. MWES was more pronounced on young maize, and rarely observed on maize older than the 5th or 6th leaf stage, indicating that younger maize is more susceptible to MWES. In a field experiment, early planting (before late July) avoided MWES and resulted in higher yields of forage maize, whereas MWES occurrence and yield loss gradually increased with late planting (from early to middle August) because of a rapid increase in C. bipunctata density during this period. Leaf and stem dry matter of the MWES-susceptible maize variety “3470” decreased together with increase in density of C. bipunctata, whereas leaf and stem dry matter of the MWES-tolerant maize variety “30D44” decreased little. These results indicate that earlier planting together with the use of MWES-tolerant varieties can significantly improve MWES control on forage maize.