وفور نسبي گونه هاي فيتوفتورا در طوقه و ريشه درختان پسته و مقايسه نسبي مقاوت طوقه و ريشه پسته به گونه هاي عامل بيماري

The prevalence of Phytophthora species, the causal agents of pistachio gummosis and root rot was investigated in Kerman and Fars provinces. From 65 isolates of Phytophthora recovered in Rafsanjan region, found to be P. drechsleri which were isolated from crown, root, water and soil at the frequency of 24,7,5 and 4 respectively which were mostly homothallic. Twenty isolates of P. cryptogea were recovered in Rafsanjan and Neirez Fars at the rate of 6, 10 and 4 respectively from water, crown and soil. This species had two types of hyphl swelling either irregular in chain or round , irregular and botryose . This species was heterothallic mostly of A l compibility types. P. citrophthora was recovered less frequently at the rate of 3,4 and I respectively form crown, root and soil. The virulence of the species on pistachio seedling cultivar Sarakhs in desending order was P. citrophthora , P. drechsleri and P. cryptogea. The reaction of crown and root of 9-month - old Pislacia vera cullivars Sarakhs, Badaini and Ghazvini to Phytophthora citrophthora (PC) and P. drechslen (Pd).was performed under greenhouse conditions. Plant height, dry weight of root and foliage, disease progress, seedling mortality and root colonization were determined. The results indicated that cultivars Ghazvini and Sarakhs were the most tolerant and susceptible respetively.Comparative reaction of crown and root of various pistachio rootstocks to PC and Pd showed that crown of the cultivars was more resistant than root to Pd but root of Sarakhs and Ghazvini and crown ofBadami showed higher resistance to PC.