Generally, trials with low C.V. rates are more reliable for making hybrid choices than trials with higher C.V. rates. Look at as many trials as possible. It is unlikely the environmental conditions of any particular test will be repeated in any future year. Oil Content Among similar-yielding hybrids, select the one with the highest oil content. Maturity Later-maturing hybrids generally yield higher than early hybrids.
Maturity is especially important if planting is delayed.
Often, with delayed planting, only an early hybrid will mature. Yield, oil content, and test weight often are reduced when a hybrid is damaged by frost before it is fully mature. An earlier hybrid likely will be drier at harvest than a later hybrid, thus reducing drying costs. The most economical and effective means of sunflower disease control is the planting of resistant or tolerant hybrids and a minimum of four years rotation between successive sunflower crops. Most sunflower hybrids in the United States have resistance to Verticillium wilt, to races 1 and 2 of downy mildew, and to two or more races of rust.