Plant height is another important factor in the production of sunflowers. The plants need to be uniform and erect for a successful, clean harvest. Yield per acre is shown in the last column of Table 1. There was a difference of only 11 pounds per acre between the top two varieties. The yields over the entire plot were low due to plant pests.
Powdery mildew is a fungus that destroys much of the plants leaf area causing a reduction in yield.
As illustrated in Table 2, the powdery mildew levels were high. Field evaluations were conducted in separate trials at the Corpus Christi Agricultural Experiment Station to determine thresholds and cost effectiveness of systemic fungicide spray programs on powdery mildew. Physical damage to the head of the plant caused by the Sunflower Moth larvae usually predisposes sunflower heads to Rhizopus headrot. In the case of this demonstration site another application of insecticide would have likely increased yields above the cost of the additional treatment. Confectionery sunflower seed is usually purchased on a clean seed weight basis, with a two-tiered price schedule according to seed size.