Differences between the effects of insecticidal seed and foliar treatments on pea leaf weevils (Sitona lineatus L.) in the field pea (Pisum sativum L.)

Tested seed treatments (two doses of thiamethoxam, thiamethoxam + fludioxonil + metalaxyl-M; two doses of clothianidin + beta-cyfluthrin) showed high effects on pea leaf weevils (Sitona lineatus) which approved relatively long-lasting and sufficient protection of several bottom nodes of stipules simultaneously. The effects of foliar treatments (chlorpyrifos + cypermethrin; acetamiprid, lambda-cyhalothrin) sometimes were evident only on the node which was determined as the youngest node at the time of spraying. The effects of the compared seed and foliar treatments on the reduction of S. lineatus larvae numbers on roots were not proven as positive. It is possible to conclude that the foliar application had no real effect in this sense at all. However, positive significant effects of thiamethoxam and clothianidin + beta-cyfluthrin on root nodulation in general were recorded. Especially higher doses of the seed treatments increased overall nodulation from 43% to 363%.