susceptibility of date palm cultivars to natural infestation by oligonychus afrasiaticus in behbehan

oligonychus afrasiaticus mcg is a key pest on kabkab and khasi date cultivars in behbehan. this research was conducted based on randomized complete block designs with 9 cultivars and 3 replications in behbehan agricultural research station during 2008 and 2009. the main idea of the investigation was the response assessment of these cultivars to the spider mite. the cultivars included kabkab, khasi, haj-mohamady and zahedi (behbehan), gantar and khazravi (shadegan), piarom and mezafati (hormozgan) and shahani (fars). infection severity and infection percentage were determined and also variance analysis, means comparison, cluster analysis and correlation analysis were administered to of the data. the results indicated that khasi, kabkab, khazravi and shahani cultivars had maximum infection with 93.28, 88, 85.29 and 85.21, respectively, and and piarom had minimum infection with 49.53 percentage. means comparison based on infection severity showed that khasi, kabkab, shahani and khasravi cultivars had maximum infection rate with 4.31, 3.65, 3.47 and 3.09, respectively, and piarom and zahedi with minimum infection rate 1.19 and 1.25. based on cluster analysis, the date palm cultivars were classified into two groups. the first group, including khasi, shahani, kabkab, khazravi and haj-mohamady were infected cultivars, and the second group, including piarom, zahedi, mezafati and gantar, uninfected cultivars. correlation analysis between infection severity, bunch weight and infection percentage was positively significant. this correlation between infection severity, stone weight and fruit skin thickness was not significant. other characters including fruit shape and color had no significant correlation.