Fig. 4. Seasonal pattern of pollen shed for the various male sterility treatments used to decrease pollen shed density. Pollen was collected on passive pollen traps placed at ear height within each treatment block. MF indicates percentage of plants allowed to shed pollen. The level of male fertility was controlled by detasselling (P3978), or by a male sterile isoline (P3925). Each point is the mean ± SE of 3 traps.