ECOLOGICAL STUDY AND SUSCEPTIBILITY OF SOME APPLE VARITIES TO ATTACK BY Dysaphis reaumuri and Dysaphis pyri

Abstract

The Results of studying the effect of some ecological factors and Ana and Vestibella apple varieties on seasonal activity of leafroll aphid Dysaphis reanmuri and Dysaphis pyri, showed a significant effect on mean number of the two aphid species a ccording to the season, apple variety and direction, the highest mean aphid number reached 25.47 Aphid/Leaf on East direction on Vestibella variety for the season 2010 The results also exhibit a significant variation between the general mean number of aphids according to the direction and reached 23.16, 9.62, 7.74 and 13.46 Aphid/leaf for East, West, North and South direction respectively. The regression equations between the mean number of aphids and biotic and abiotic factors showed a clear effect on mean aphid seasonal activity and the rain exhibit ahighest effect on mean aphid number and reached ٪66 – 6 while the effect of wind and temperature on mean number of parasites were 67. and 59.6% respectively.