Symptoms of maize rough dwarf disease (MRDD) caused by Rice black-streaked dwarf virus (RBSDV) in the field.

(A) MRDD symptoms on maize heavily infected with RBSDV under natural field conditions. (B and C) Lower surfaces of a RBSDV infected leaf showing dark leaf greening and vein clearing with small white enations and plant dwarfing. Note: Plants were photographed at 4 weeks after feeding access by viruliferous planthoppers. (D) Effects of different planting dates on MRDD incidence. The center plot shows MRDD in heavily infected RBSDV maize that had been planted in northern China at the end of May, 2011 before harvest of surrounding wheat fields. Under these conditions, high concentrations of planthoppers migrate from maturing wheat to emerging maize seedlings and transmit RBSDV. The vigorous plants on each side of the RBSDV-infected plants were planted on June 18, 2011 after wheat in surrounding was harvested and most of the planthoppers had dispersed. The infected plants failed to develop tassels and had very small cobs with greatly reduced seed set, and often died. Plants were photographed on Sep. 7, 2011. Note: This area of China is in a wheat-maize rotation region and maize planted before wheat harvesting generally develops very high levels of MRDD because planthoppers preferentially move from mature wheat to new maize seedlings.