The Reaction of Apple Cytospora Canker to Nutrient Nitrogen and Potassium

In an assessment for determination the role of nitrogen and potassium on incidence and development of Cytospora spp. associated with apple trees، 52 Golden delicious gardens randomized selected and sampled from leaves and soils (0-30، 30-60 cm deep) in Junuary. Sample compound prepaired in laboratoary، macro and micro elements based on Wet Digestion Method analyzed. The results were subjected to analyzed and required discussious، based on Deviation from Optimum Percentage (DOP) method in infected gardens to recent index concentration in non infected ones. Potassium deficiency and high level of nitrogen were observed in infected gardens. Research on the role of these elements were performed on the fungus. This part of invastigation was done on seedlings of the two-years-old Golden Delicious apple cultivars، in factorial randomized block design with two factors (16 treatments) and four replications. After 6 weeks، seedlings were inoculated with high virulence isolate. In most treatments callus tissue was formed around the site of inoculation in late spring and along summer. But the invasion of health tissues began in the fall، and cankers caused seedlings were dead. The results showed that only tissue callus was formed around the replications: N0K0، N0K115، N0K230، N0K345، N105K230. N105K345، while none of the treatmens were dried. In treatments K0N105، K0N210، N105K115، N210K230، N210K345، N315K345، 25% of replications were dried. In treatments K0N345، N210K115، N315K230، % 50 repetitions، while in treatment N315K115، % 100 repetitions were dried. It''s characterized by increasing potassium and reduce of nitrogen in treatments، percentage of deaths variable and it''s increasing. This results were the same results obtained from health and infected apple trees leaves and soils.