Effect of pot marigold (Calendula officinalis L.) and cypress spurge (Euphorbia cyparissias L.) plant water extracts on the occurrence of pest insects on white cabbage

In 2007-2008 the effects of pot marigold (Calendula officinalis L.) and cypress spurge (Euphorbia cyparissias L.) water extracts on the occurrence of pest insects on white cabbage were tested. The numbers of cabbage aphid (Brevicoryne brassicae L.) were significantly lower on the treated plants. During the period of the most numerous occurrence of aphids on the unsprayed plants, their number was almost twice as high as on the plants sprayed with spurge extract and almost three times as high as on the plants sprayed with marigold extracts. Spraying plants had an effect on the number of Phyllotreta atra and P. nemorum beetles and Pieris rapae L. eggs. Pot marigold extract proved to be the most effective in this respect. Egg clusters of large white butterfly (P. brassicae L.) and cabbage moth (Mamestra brassicae L.) were observed only in 2008, and only on the control. In the case of the diamondback moth, Plutella xylostella L., only marigold extract had a positive impact on reducing its number. Diamondback moth larvae numbers were even slightly higher on plants treated with cypress spurge extract than on the control plots where plants had not been sprayed.