European Red Mite Control and Population Studies on Apple in Wisconsin1

Abstract

Genite® (2,4-diehlorophenyl benzenesulfonate), Mitox®(p- chlorobenzyl p-chlorophenyl sulfide), and ovex applied as preblosson aearicides provided season-long control of the European red mite, Panonychus ulmi (Koch), on apples in Door County, Wisconsin, during 1956 and 1957. Aramite® (2-(p-tert-hutyl phenoxy)- 1-methylethyl 2-chloroethyl sulfite), Chlorobeuzilate® (ethyl 4,4'-dichlorohenzilate), demeten, Kelthane® (1,1-bis(p- chlorophenyl)-2-2-2-triehloroethanol), and Mitox, used as sum- mer foliar sprays, were effective in reducing and maintaining the mite populations at low levels for the remainder of the season. The results of 3 years' study of the European red mite populations arc given. There were five generations in 1956 and 1957 and four generations in 1958. The populations normally reached their highest peak at the end of July and then abruptly decline. The first summer eggs were oviposited by blossom time. Overwintering eggs were laid the first week in August. The highest number of eggs were oviposited by the first summer generation adults. European red mite populations on treated trees exceeded those on the check (untreated) trees the first of September, remained at a higher level until the end of the season, and oviposited more overwintering eggs than populations on the check trees. The number of overwintering eggs oviposited in the treated plots were proportional to the degree of control obtained. The 1958 populations, which developed from overwintering eggs laid on the trees in the 1957 treated plots, were higher and reached peaks earlier than those on the trees which had been a part of the check plot in 1957. Predaceous typhlodromid mites, the only predators observed throughout the studies, were in very low numbers in the 1956 and 1957 check plots. Typhlodromids were more numerous on the unsprayed trees in 1958. They were present the first week in July; gradually increased in numbers; and finally surpassed the European red mite population in mid- August. Two species were present. The primary one, Typhodromus fallacisi (Garman), comprised fl.5% of the population.