STUDIES ON MANAGEMENT OF POSTHARVEST ANTHRACNOSE DISEASE OF PAPAYA (Carica papaya) USING BIOLOGICAL CONTROL AGENTS
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Date
2018-07
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University of Horticultural Sciences, Bagalkot
Abstract
An experiment entitled “Studies on management of postharvest anthracnose
disease of papaya (Carica papaya) using biological control agents” was conducted in
the Department of Agricultural microbiology and Post-Harvest Technology, COH,
Bagalkot, Karnataka during the year 2017-2018. The Isolates of anthracnose causal
agent Colletotrichum gleosporiodies were isolated from infected papaya fruits
collected from different places. The virulent pathogen isolate exhibiting higher per
cent disease index (30%) and virulence index (4.29) was selected for isolation of
biocontrol agents from different sources by Poisoned food technique. Out of 59
samples tested, 19 biocontrol agents exhibited clear zone of inhibition in poisoned
food technique and were selected for further evaluation against pathogen under in
vitro by Dual culture technique. Among the biocontrol agents tested, Trichoderma
harzianum was most effective with maximum per cent inhibition of radial growth of
C. gloeosporioides (62.50%) followed by isolate No. 10 (50.00%), isolate No. 9
(47.85%), isolate No. 7 (47.14%) and isolate No. 16 (46.43%). Five efficient
biocontrol agents selected from in vitro studies were screened in vivo against infection
of anthracnose disease of papaya fruits and their inoculation effect on the conditions.
The results of the in vivo evaluation of biocontrol agents against natural
infection of anthracnose (C. gloeosporioides) showed the lowest per cent disease
index of 13.89 per cent in fruits treated with T5 (BCA5- Isolate No. 9), followed by T4
(BCA-Isolate No.10) (16.67%) and T7 (Carbendazium at 0.1 per cent for 5 min)
(20.83%). The papaya fruits treated with T5 (BCA5-Isolate No.10) exhibited higher
shelf life of 10 days with minimum physiological loss in weight (16.23%), higher
firmness (2.16 N) and higher TSS (14.10o brix), total sugars (11.63%), ascorbic acid
(38.19 mg/100 g) and carotene content (1.85 mg/100 g) and higher sensory score at 9
days of storage followed by T4 (BCA-Isolate No.10) and T7 (Carbendazium at 0.1 per
cent for 5 min).
In vivo screening of efficient biocontrol agents on papaya fruits challenge
inoculated with C. gloeosporioides showed that fruits treated with BCA5-Isolate No.
10 (T5) recorded lower per cent disease index (33.33%) followed by BCA4 -Isolate
No.9 (T4) and Carbendazium at 0.1 per cent (T7) with PDI of 50.00 per cent and 52.77
per cent respectively at 9 days of storage. The papaya fruits treated with T5 (BCA5 -
Isolate No. 10) recorded higher shelf life of 9.67 days with lowest per cent
physiological loss in weight (16.13%), higher firmness retention (2.22 N), higher TSS
(12.47o brix), total sugars (10.40 %), ascorbic acid content (30.19 mg/100 g) and
carotene content (1.42 mg/100 g) and higher sensory score 9 days of storage followed
by BCA4 -Isolate No.9 (T4) and Carbendazium at 0.1 per cent (T7).