Recent Developments in Plum Curculio Investigations in Georgia

Abstract

The establishment of the occurrence in the latitude of Central Georgia of two generations annually of the plum curculio, Conotrachelus nenuphar, and that a large percentage of the larvae injuring the best late varieties of peaches are larvae of the second generation were the most important truths revealed as a result of extensive investigations started in 1921. They followed the most severe outbreak of the plum curculio that has ever occurred in the South, when Georgia peach growers lost several million dollars from curculio damage. A third generation was carried through in the insectary in 1922. Picking up and destroying the small peaches that fell several weeks after the pollination season assisted greatly in correcting Georgia's abnormal curculio conditions, and is a wise supplementary control measure in latitudes where there are two generations of the insect. In one orchard a net saving of $5.25 per acre resulted from the operation. Discing to break up the pupal cells in the soil and burning over hibernating quarters during the winter months are other supplementary control measures that were successfully utilized. The investigations show that the ideal spraying or dusting schedule for the control of the plum curculio on peach in latitudes where there are two generations, consists of four treatments of arsenate of lead as follows; (1) Immediately after the petals fall; (2) When the fruit is exposed from the calyx; (3) two weeks after the second; and (4) four weeks before each variety is due to ripen. Four applications of lead is too much as an annual treatment for peach trees in the South. The four application schedule should be used when the curculio infestation is heavy, otherwise the lead in the third application should be omitted.