PLANTING DATE IN RELATION TO CASSIDA VITTATA VILL. (COLEOPTERA: CHRYSOMELIDAE) INFESTATION AND YIELD COMPONENTS IN SUGAR BEET FIELDS

The tortoise beetle, Cassida vittata Vill., (Coleoptera: Chrysomelidae) is a serious pest on sugar beet causes losses in root yield and sugar content in Egypt.In this work, five field free of pesticides planted (with Raspoly sugar beet variety) at five different dates through August to October 2005 were chosen at Shirbin, Dakahlyia governorate, in 2005-2006 season.In each field, yield components and level & intensity of infestation were determined.These findings were greatly varied according to sowing date, sugar beet planted during the first half of August had a low yield (18.6 tons / fed.) with 19.5% sugar content.The yield increased progressively with delaying the date to reach 29.8 tons/fed.with 18.1% sugar content for October 1 plantation.The late plantation of October 20 harbored a light yield (19.6 tons /fed.) with the lowest sugar content (17.9%).The infestation firstly appeared in a low level of 10% infested leaves and 7.6 pores / 4 leaf discs on September, reached 100% and 45.2 pores in the last plantation.Also, the estimated highest average of income loss was found in the late plantations as about 1493 L. E. / feddan (about 32.5%) when compared with the free infested early plantations during August.On the other hand, the plantations of September 15 and October 1 received light infestation and low pores recognized the highest income.Therefore, early planting during August and September, could be followed for sugar beet crop as one of the best agricultural control method INTRODUCTIONSugar beet, Beta vulgaris L., is the second sugar crop in Egypt.This crop faces several problems that reduce its yield, of which the tortoise beetle, Cassida vittata Vill.. Few studies pertaining to the effect of planting dates on the infestation by this