Susceptibility of different date palm varieties against Parlatoria blanchardii in hyper arid region of Rajasthan

In this field investigation during 2017–2019, different varieties of Date Palm were investigated against Parlatoria blanchardii. Ten varieties were selected based on arid climate, and local regions. Nymph and adult insects were counted on 1 cm² area of the lower surface of date palm leaflets and recorded together opposite to each inspected date palm at weekly intervals. Out of ten varieties screened for their relative susceptibility against date palm scale, P blanchardii and revealed that none of them was found free from the scale attack. The varieties having population less than 15.19/cm² were rated as less susceptible, those varieties having population more than 15.19/cm² scale and up to 25.63/cm² scale rated as moderately susceptible and the varieties having more than 25.63/cm² population rated as highly susceptible to scale insect. Considering this formula varieties viz., Zagloul and Zahidi were rated as less susceptible with highest yield production 127 kg and 130 kg per plant/year respectively., Sewi, Shamran, Khasab, Khadrawy and Khuneizi as moderately susceptible, whereas, Halawy, Medjool and Barhee, were noticed highly susceptible to scale insect.