CHARACTERIZATION AND MANAGEMENT OF FRUIT ROT OF POMEGRANATE CAUSED BY Colletotrichum gloeosporioides AND Alternaria alternata
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Date
2021-01
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University of Horticultural Sciences, Bagalkot. (College of Horticulture, Bagalkot).
Abstract
Pomegranate is one of the important horticultural crops infected by several pathogens.
Among them anthracnose and heart rot are the most severe post harvest diseases in pomegranate.
Fruits with typical symptoms were collected to isolate pathogens associated with anthracnose and
heart rot diseases. The causal agents of anthracnose and heart rot were confirmed as Colletotrichum.
gleoesporioides and Alternaria alternata respectively through pathogenecity test, cultural,
morphological and molecular identification. Among different media, oat meal agar (90.00 mm) was
found to be the best solid culture media. Potato dextrose broth was found to be best liquid media for
the growth of both the pathogens.
Fungicides evaluated under in vitro against C. gleoesporioides and A. alternata revealed
that mancozeb 75% WP, zineb 75% WP, tricyclazole 18 % + mancozeb 62 %, carbendazim 12% +
mancozeb 63% and carboxin 37.5% + thiram 37.5% completely inhibited the growth of both the
pathogens at 1000, 1500, 2000 and 3000 ppm. Propiconazole 25% EC, hexaconazole 5% EC,
iprobenfos 48% EC and kresoxim methyl 44.3% EC at 250, 500 and 1000 and 2000 ppm completely
inhibited the growth. Among bio agents Trichoderma harzianum, UAS, Dharwad isolate was most
effective in inhibiting the mycelia growth of C. gloeosporioides and A. alternata with 86.67% and
87.78% respectively. Under field condition application of two sprays of propiconazole 25% EC @
0.025% , mancozeb 75% WP @ 0.1% and carbendazim 12% + mancozeb 63% @ 0.1% showed least
fruit rot PDI of 36.00%, 37.33% and 37.33% respectively.
Post harvest management studies revealed that propiconazole 25% EC recorded least PDI
(7.22%) followed by hexaconazole 5% EC (12.78%), NaOCl (4%) + CaCl2 (10%) (12.78%) and
carboxin 37.5% + thiram 37.5% (13.89%). Least physiological weight loss was recorded in
propiconazole 25% EC treated fruits (9.53%) followed by chitosan 1% (12.37%) and NaOCl (4%) +
CaCl2 (10%) (12.67%) treated fruits. NaOCl (4%) + CaCl2 (10%) showed maximum firmness (45.42
N) followed by propiconazole 25% EC (45.23 N), kresoxim methyl 44.3% EC (44.28 N) and
carboxin 37.5% + thiram 37.5% (44.25 N). NaOCl (4%) + CaCl2 (10%) and propiconazole 25% EC
recorded least TSS content of 19.12 and 19.18 0B, respectively. Propiconazole 25% EC recorded
highest mean titrable acidity (1.82%) followed by NaOCl (4%) + CaCl2 (10%) (1.63%) and zineb
75% WP (1.56%). The highest ascorbic acid retention was recorded in propiconazole 25% EC
treated fruits (18.23 mg/100g) followed by hexaconazole 5% EC (17.55 mg/100g) and kresoxim
methyl 44.3% EC (16.51 mg/100g).
Among different post harvest treatments tested propiconazole 25% EC @ 250 ppm,
hexaconazole 5% EC @ 250 ppm and NaOCl (4%) + CaCl2 (10%) application can reduce losses
caused by fruit rots during storage of fruits at room temperature.