Abstract
Eggs of the winter grain mite in the soil of Italian ryegrass fields tilled with a rotary plow are mostly distributed within 10cm of the soil surface. They are distributed more deeply (15cm or more) when the Italian ryegrass fields tilled with a moldboard plow. This suggests that moldboard plowing buries eggs of the winter grain mite more deeply than rotary plowing. This was confirmed by field experiments in which mite eggs were buried artificially at various depths and the subsequent number of emerging mites was examined. The emergence rate of young nymphal mites decreased with an increase in the egg burial depth. Moldboard plowing reduces the initial population of winter grain mites in a field by 91.6-94.8%. On the other hand, 59.5% to 31.0% of mites remain after rotary plowing. The results indicate that tilling by moldboard plowing in fields of cool season grass is a profitable management measure for controlling the winter grain mite.
