Saffron is one of the most important horticultural crops in Gonabad, Iran. There are many families that earn their livelihood with Saffron planting and it makes a considerable amount of income annually. Rhizoglyphus robini is the most harmful mite in saffron fields. This species causes corm rotting in soil which finally results in yield losses. To determine the effects of depth of planting and summer irrigation, the present study was conducted in Gonabad Agricultural and Natural Resources

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... n during 1999-2005 period. The study was laid out in factorial experiment based on Randomized Complete Block Design with four replications. The experiment consisted of three levels of planting depth and four levels of summer irrigation. Results showed that summer irrigation significantly increased mite population and yield 1osses. Depth of planting had not any significant influence on the mite population in spring, autumn and winter, while significant increases in mite population in the depth of 10 and 30 cm were observed in summer. Increasing depth of plantings resulted in the increasing of black spots on corms. The interaction of summer irrigation and depth of planting revealed that applying two irrigation maximize the mite population in all depths. However the minimum levels of mite population as well as black spots were observed with no irrigation. Higher the depth of deeper the corms planted higher the number of black spots found in plots with two irrigations. Higher mite population was observed in fields with higher planting record.