Twenty one wheat cultivars were evaluated in trials carried out at Paranapanema Valley Region, Southwest of the State of Sao Paulo, Brazil, taking into account the grain yield and the reactions to the causal agents of leaf spot, leaf rust and mildew. The amount of rainfall was divided in periods of ten days in each month (March to October). The rain excess occurred during the second period of ten days on June, 1987, increased the occurrence of the evaluated diseases. The cultivars OCEPAR 14, IAC 227, IAPAR 17, IAC 60, IAC 28, IAC 18, IAC 17 and IAC 21 showed higher grain yields than the 'BH 1146' used as control, and the cultivars OCEPAR 7 and Alondra presented the lowest yields. The leaf spot, caused by Cochliobolus sativus exhibited generalized occurrence in the evaluated trials increasing in intensity as the amount of rainfall increased. The occurrence of leaf rust and mildew was variable and presented low frequency during the period.
wheat; cultivars; disease resistance; grain yield; rainfall index