Feeding damage by onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), on early white cabbage grown under insecticide-free conditions.

摘要

The effects of cultivar choice and plant density on onion thrips (Thrips tabaci) damage to early white cabbage was studied on five varieties of early white cabbage grown at three different densities over two years. In the drier year the cabbage yield was smaller and greater thrips damage was recorded. The cabbage variety 'Vestri', which had on average the firmest head, showed itself to be the most resistant to Thrips tabaci attack and gave the highest yield. The 'Parel' variety, with the shortest growing period, was the most damaged by the thrips. Most densely planted cabbage had the lowest mean weight of heads and the lowest mean index of damage on the exterior leaves. Most of the economically important damage occurred between the third and sixth exterior leaf, although the damage extended to the fifteenth exterior leaf.