National Academy of Agricultural Sciences (NAAS)
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PRINT ISSN : 2319-7692
Online ISSN : 2319-7706 Issues : 12 per year Publisher : Excellent Publishers Email : editorijcmas@gmail.com / submit@ijcmas.com Editor-in-chief: Dr.M.Prakash Index Copernicus ICV 2018: 95.39 NAAS RATING 2020: 5.38 |
Premature leaf fall is one of the most important diseases of apple particularly in Himachal Pradesh. Present studies were carried out with the objectives to study the mode of survival of Diplocarpon mali in the infected leaf litter, to study the effect of time of leaf fall, cultivar and environment on the perennation of Diplocarpon mali. Acervuli of Marssonina coronaria were found to occur in all the leaf samples while conidia formation started in or after May ranging from 1.2x103 to 5.8x103 conidia per ml at all the locations but its ascosporic stage and apothecia were not observed in any of the leaf samples. Leaves collected on September 28, 2013 produced the highest number of conidia (5x103 conidia/ml) in the summer and the conidial production started from pea stage of apple bud development and the maximum production of primary inoculum was observed at pre-harvest stage (9.2x103 conidia/ml). Maximum number of conidia was caught on the greased slides on 7th August 2014, when the temperature was 19ºC with ample rainfall and relative humidity above 85 per cent in the preceding 24 hours. Also, rainfall and relative humidity were significantly and positively correlated with number of conidia released in the apple orchard, whereas, the maximum temperature showed a negative correlation. Among the test apple cultivars, Golden Delicious produced maximum number of conidia in the overwintered leaf litter followed by Royal Delicious, Red Gold, Rich-a-Red, Scarlet Gala and Tydeman’s Early Worcester and Granny Smith respectively.
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