STUDIES ON MOULDY CORE AND CORE ROT OF APPLE CAUSING PREHARVEST FRUIT DROP
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Date
2009
Authors
HANS, RAJ
Journal Title
Journal ISSN
Volume Title
Publisher
UHF,NAUNI,SOLAN
Abstract
Abstract
The present investigation entitled “Studies on mouldy core and core rot of apple causing preharvest fruit
drop” was undertaken to study the occurrence and incidence of mouldy core and core rot of apple in Shimla
district of Himachal Pradesh including isolation and identification, pathogenicity test, cultural
characteristics, epidemiological studies in relation to disease initiation and spread of Alternaria alternata
the major pathogen involved in mouldy core and core rot of apple. In vitro evaluation of different plant
extracts, oils and biocontrol agents of fungal and bacterial origin was also undertaken in present
investigation. In vitro and in vivo evaluation of systemic and non-systemic fungicides was undertaken to
control the diseases in the field. Maximum incidence (17.70 %) of mouldy core and core rot was recorded
at Kotkhai with on an average 16.2 per cent incidence of both these diseases in the surveyed areas of
Shimla district. Alternaria alternata was found consistently associated with mouldy core and core rot
causing preharvest fruit drop. Its pathogenicity was proved by standard methods and identity was
confirmed from standard literature. The pathogen associated with the disease grew best on potato dextrose
agar medium at 250C temperature and 6.5 pH. Potassium nitrate and maltose were best nitrogen and carbon
sources supporting maximum growth of the Alternaria alternata. For germination of conidia of Alternaria
alternata, 30°C temperature and 100 per cent relative humidity were found optimum under in vitro
conditions. Among different weather parameters, cumulative rainfall was directly correlated with disease
development during both 2008 and 2009 cropping seasons. Regression analysis further showed that the
91.00 per cent variation in preharvest fruit drop was due to mouldy core and core rot. Medium sized
Starking Delicious apple fruits with open sinus/calyx tube and length : width ratio falling in 0.96 to 1.05
mm class showed maximum incidence of mouldy core and core rot in the field. Among different plant
extracts and essential oils tested in vitro, mehandu (Dodonia viscosa) extract and cinnamon (Cinnamomum
camphora) oil gave the maximum growth inhibition of Alternaria alternata. Among the biocontrol agents,
Trichoderma hamatum exhibited the maximum inhibition. Under laboratory conditions, EBI fungicides
difenoconazole and hexaconazole, and non-systemic fungicide iprodione + carbendazim gave maximum
inhibition of mycelial growth as well as spore germination of Alternaria alternata. In the field, EBI
fungicides (difenoconazole, hexaconazole and myclobutanil) and protectant (mancozeb flowable, dodine
and captan) gave better disease control. Three sprays of difenoconazole sprayed at pink bud, full bloom and
petal fall stages of apple provided 94 per cent control of mouldy core and core rot followed by sprays of
mancozeb (at pink bud), difenoconazole (at full bloom) and hexaconazole (at petal fall) with 90 per cent
disease control without hampering the fruit set.
Description
Keywords
economics, biological phenomena, resins, productivity, technological changes, exhibitions, developmental stages, marketing, biological development, selection