واكنش ارقام مختلف توت به بيماري سفيدك پودري و تاثير آن بر پارامترهاي كيفي برگ توت

Investigation on different mulberry varieties’s response against mulberry powdery mildew and its effect on qualitative traits of mulberry leaf

Harmful effects of chemical control of mulberry pests and disease for silkworm rearing will make the selection of high resistant plants to play a manificant role on improvement of sericultural activies. Recognition and propagation of high disease resistant varieties of mulberry will prompt the quality and quantity effeciency of mulberry leaf as exclusive feeding resource for silkworm rearing and improve cocoon and silk output consequently. Mulberry powdery mildew is known as one of the most important fungous disease all over the world. During this studying at 2000-2001, Phyllactinia guttata was recognized as pathogen of disease in Gilan and 4 improved mulberry varieties i.e. KM, KN, I and SI as well as one local variety have been studied at Pasikhan site of Iran Sericulture Co. First year evaluation was based on natural contamination of 625 leaves of each variety selected from 25 trees as a colon. At second year, after relative expansion of disease from the most susceptible areas of Gilan (Roudbar and east zones) the infected leaves were collected and washed in 0.78% Glucose solution. The prepared suspensoid with concentration of 2×105 conidia/ml were sprayed on isolated sapling of each 5 varieties (each variety 10 sapling). After 10 days KM variety showed the first symptoms of disease under greenhouse conditions. 5 leaves of each tree were surveyed after full expansion of disease under natural condition and contamination level were coded based of 0-7 scale . Severity index (S.I. or PDI) during two years in spite of slight differences showed the following fashion: SI< I < KN< Local< KM.Chemical analysis of normal and infected leaves from the aspect of qualitative parameters such as protein etc. showed decreasment(sometimes increasement) in infected leaves in each variety which was corresponded with the mode of severity index of varieties.