Disease reaction of apple germplasm (Malus species) to powdery mildew (Podosphaer leucotricha Ell. & Ev.) Salm and White root rot (Dematophora necatrix)
2011
Sharma, Y.P. | Kishore, D.K. | Pramanick, K.K. | Thakur, J.S.
Twenty one Malus species were evaluated for their reaction to powdery mildew (Podosphaera leucotricha) and white root rot (Dematophora necatrix) under artificially inoculated conditions. Different Malus species exhibited differential reaction with respect to incubation period and mildew intensity. Five species viz., M. baccata (Shillong), M. baccata (Kashmir), M. prunifolia (Maruba), M. purpuria and M. zumi were found resistant to the powdery mildew. These species exhibited prolonged incubation period varying from 9 to 17 days besides low mildew intensity. M.baccata (Shillong) was found to possess higher level of resistance than M. zumi – a known source for imparting powdery mildew resistance in apple progenies. Rooted suckers of twenty one different Malus species were evaluated under artificially inoculated field conditions. Different species exhibited differential reaction to root rot development parameters. Evaluation under sick plot revealed that none of the species exhibited higher level of resistance. However, some of the species like M. prunifolia var ringoasami and M. purpuria could delay the expression of disease symptoms indicating the tolerance to the disease pressure. Malus Baccata (Kashmir) restricted the disease development to some extent better than the other indigenous crab apples. These three Malus species were further evaluated at variable disease pressure. Marked differences with respect to disease progress curve and mortality rate was observed at lower disease pressure. Maximum tolerance was recorded in M. prunifolia var ringoasami followed by M.purpuria at lowest disease pressure.
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