STUDIES ON SCAB OF POMEGRANATE CAUSED BY Sphaceloma punicae Bitanc.
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Date
2019-09-04
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK, BENGALURU
Abstract
Scab caused by Sphaceloma punicae Bitanc. is a serious fungal disease of
pomegranate. The present investigation was undertaken to know the severity of scab
disease in southern Karnataka, evaluation of fungicides, bio-agents and botanicals against
S. punicae. Survey revealed that, the maximum per cent disease index (PDI) of scab was
observed in Tipaturu (15.56) and Kanakapura (13.65) during the survey. The pathogen was
identified as Sphaceloma punicae based on pathogenicity test and morphological
characterization viz., septate mycelium, conidia were 2.9–4.8 × 10.2–12.0 μm in size, ovoid
to sub-cylindrical, unicellular and hyaline in nature. The maximum radial growth of
pathogen (90.00 mm) was observed on oat meal agar followed by potato dextrose agar
(86.43 mm). The temperature of 30 °C and pH 6.5 were found ideal for growth of the
pathogen. Under in-vitro studies, the systemic fungicides viz., tebuconazole,
propiconazole, thiophanate methyl and carbendazim along with combi-products viz.,
azoxystrobin + mancozeb, hexaconazole + zineb, fenamidone + mancozeb, and
carbendazim + mancozeb at 250, 500 and 1000 ppm concentration showed completely
inhibited the growth of pathogen. The contact fungicides propineb and mancozeb at 1000
ppm recorded complete inhibition of the pathogen. Among the nine plant extracts,
maximum mycelial inhibition (73.63 %) was observed in garlic extract. Among the six
fungal bio-agents, Trichoderma harzianum (Th-14) showed 83.15 per cent inhibition of
pathogen. Whereas the bacterial bio-agent Bacillus amyloliquefaciens showed maximum
mycelial inhibition of 64.60 per cent. The above fungicides can be exploited for the
management of scab of pomegranate.