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.