SEASONAL OCCURRENCE OF BARLEY YELLOW DWARF VIRUS SEROTYPES IN SMALL-GRAIN CEREALS IN THE VALLEY OF MEXICO

We assessed the occurrence of serotypes of barley yellow dwarf virus ( BYDV) in an area at the International Maize and Wheat Improvement Cent er (CIMMYT) used to screen germ plasm for field resistance to BYDV. Wh eat and barley plants were labeled in the field, and leaves were sampl ed several times during plant development to monitor BYDV incidence. S amples were tested by enzyme-linked immunosorbent assay with a panel o f monoclonal and polyclonal antibodies. Samples from plantings sowed o n different dates were tested to investigate seasonal influences on BY DV occurrence. Up to 88% of the plants sowed in winter (November and J anuary) became infected. Fewer infections were detected in summer sowi ngs (May). MAV serotypes predominated in both winter and summer sowing s.