Pest description and crop damage "Silvertop" is a condition in grasses in which the seed head turns white and dries off before some or all seeds develop. Silvertop is most noticeable in fine-leaf grasses (bluegrasses, bents, and fine fescues). It can be the result of weather, poor pollination, insect damage, and/or disease.
In western Oregon, meadow plant bug and thrips can produce silvertop symptoms in fine-leaf grasses when feeding activity injures plant tissue essential to normal seed development and maturity. Silvertop produced by meadow plant bug can be distinguished by injury to the stem below the seed head. The stem kinks and withers where the insect's mouth parts were inserted.
In annual ryegrass, silvertop is caused by larva of the cereal stem moth, which bores into and damages the conductive tissues transporting nutrients to the seed head.
See meadow plant bug, grass mealybug and thrips for managing these pests when they are the causal agents of silvertop in grass seed fields.