§ 201.78 Pollen control for hybrids.

(a) Wheat and barley. Shedders in the seed parent, at any one inspection, are limited to 1:200 heads for Foundation A Line and 1:100 heads for Registered A Line, except that when the A Line is increased outside the area of the anticipated A × R production in order to utilize self-fertility produced by environmental effects, only isolation and genetic purity standards will be in effect. (An A Line is a cytoplasmic male sterile female line used to produce hybrid seed. An R Line is a pollinator line used to pollinate an A Line and to restore fertility in the resulting hybrid seed.) (b) Corn. When 5 percent or more of the seed parent plants have receptive silks, shedding tassels in the seed parent plants shall be limited to 1 percent at any one inspection, or a total of 2 percent at any three inspections on different dates. Shedding tassels are those which have 2 inches or more of the central stem or branches, or any combination thereof, shedding pollen. (c) Sorghum. Shedders in the seed parent, at any one inspection, are limited to 1:3,000 plants for Foundation class and 1:1,500 plants for Certified class. (d) Sunflowers. Seed parents flowering and shedding pollen before the male parents are shedding pollen must be removed. At least 50 percent of the male plants must be producing pollen when the seed parent is in full bloom. (e) Hybrid alfalfa. When at least 75 percent of the plants are in bloom and there is no more than 15 percent seed set, 200 plants shall be examined to determine the pollen production index (PPI). Each plant is rated as 1, 2, 3 or 4 with “1” representing no pollen, “2” representing a trace of pollen, “3” representing substantially less than normal pollen, and “4” representing normal pollen. The rating is weighted as 0, 0.1, 0.6 or 1.0, respectively. The total number of plants of each rating is multiplied by the weighted rating and the values are totaled. The total is divided by the number of plants rated and multiplied by 100 to determine the PPI. For hybrid production using separate male and female rows, the maximum PPI allowed for 95 percent hybrid seed is 14 for the Foundation class, and 6 for the F1 hybrid. For hybrid production using comingled parent lines, the maximum PPI allowed for 75 percent hybrid Certified class seed is 25, with an allowance for blending to reach a PPI of 25 for fields with a PPI above 25, but no greater than 30.