Influence of abiotic factors on the population density of phytophagous mites on various apple cultivars in Kurram Valley, Parachinar, Pakistan

Role of climatic factors on the population density of phytophagous mite, Panonychus ulmi (Koch) was study in the Roberts Garden, Agriculture Extension Department, Parachinar, Kurram Valley for two consecutive years from 2007 to 2008. Number of these mites was recorded on ten apple cultivars viz., Red Delicious, Red Chief, Sky Spur, Amri, American Golden, Shine Kulu, Qandari, First Kasmari, Mashadi and Nazuk Baden. Meteorological observations relevant to ambient temperature, relative humidity and rainfall, were recorded from the adjoining meteorological observatory of the Parachinar, Kurram Valley. Population of P. ulmi reached to the maximum level on September 08, 2007 and on July 26, 2008, when the mean temperature and relative humidity was high. The mite was most abundant towards Western side of the plant canopy as compared to southern direction. Northern and Eastern directions were least preferred. On cumulative basis of the two year's study, minimum average temperatures and relative humidity had a significant positive correlation with the population of phytophagous mite. Minimum temperature played significant role in the P. ulmi population. Significant variations were found to exist among various dates of observation regarding population of phytophagous mite on apple during 2007 in Parachinar, Kurram Valley. Means were compared by LSD Test at P = 0.05. Maximum population of harmful mite were recorded to be 7.36 mite/leaf on September 8, 2007 and did not differ significantly with those of recorded on August, 24 showing 7.23 mite/leaf. Population of this mite, on May 24, 2007 was 0.18 mite/leaf and increasing trend observed thereafter on the subsequent dates of observation up to 7.23 mites/leaf on August 24, 2007. A non-significant decrease was observed thereafter on August 31 with 6.97 mite/leaf. This population reached to the highest peak i.e. 7.36 mite/leaf on September 08. A steep declining trend was found thereafter on the subsequent dates of observation and the population reached to the level of 0.63 mite/leaf on October 06, 2007.