Investigations into seed setting in cocksfoot seed crops in New Zealand

Abstract

Surveys in cocksfoot seed producing districts of the South Island showed that seed-setting in cocksfoot was very variable. A wide range of thrips infestation in the cocksfoot florets was found, usually greater in older stands. The thrips found was identified as Chirothrips pallidicornis Priesner. It appeared that the overwintering thrips laid eggs inside the cocksfoot florets before flowering. The first-generation larval thrips destroyed the floral parts before flowering and the first-generation adults laid eggs in florets at or near anthesis, the second-generation larvae destroying the developing seed. The second-generation adults were thought to overwinter inside florets at or near the base of the cocksfoot plant. In all material examined, a certain proportion of undamaged cocksfoot florets failed to set seed, this failure being a significant factor in reducing seed yield.