EPIDEMIOLOGY AND MANAGEMENT OF EARLY BLIGHT IN POTATO CAUSED BY Alternaria alternata L.
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Date
2021-09-09
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COLLEGE OF AGRICULTURE, UMMEDGANJ, KOTA
Abstract
Early blight caused by Alternaria alternata is a destructive disease which causes heavy
losses in tuber yield of potato in South Eastern Rajasthan. Surveys were conducted to determine
the incidence of early blight in Kota, Baran and Bundi districts of South-Eastern Rajasthan and
revealed that disease incidence was ranged from 12.5 to 23.8 per cent. The maximum disease
incidence was recorded in Anta village of Baran district 23.8 per cent while, minimum was
recorded in Suvana and Keshoraipatan village of Kota and Bundi district 12.5 per cent.
A field experiment was conducted to assess the progress of early blight disease intensity
as influenced by three planting dates and four varities. The four varities i.e. Kufri Bahar, Kufri
Sindhuri, Kufri Pukhraj and Kufri Pushkar were planted at every fifteen days interval i.e. 23rd
Oct, 6th Nov and 20th, Nov, 2019, respectively. Out of three planting dates, minimum disease
intensity was recorded with 2nd date of planting (6th Nov, 2019) in K. Sindhuri (8.5 %) followed
by K. Pushkar (11.5 %), K. Bahar (21.5 %) and K. Pukhraj (30.0 %) as compared to 1st (23rd
Oct, 2019) and 3rd (20th Nov, 2019) date of planting. Minimum per cent disease intensity of
early blight was recorded in variety K. Sindhuri (12.5 %) and K. Pushkar (13.5 %).
Epidemiological studies revealed that maximum and minimum temperature was highly
significant with negative correlation. The yield data indicated that planting on 6th November i.e.
2nd date of planting produced maximum total number of tubers per plot, marketable yield and
total tuber yield (t/ha) and among the varieties maximum total tuber yield and marketable yield
were obtained i.e. 16.7, 18.2, 14.9, 17.3 and 14.3, 16.9, 13.7, 15.6 t/ha in K. Bahar, K. Sindhuri,
K. Pukhraj and K. Pushkar, respectively. Hence, first week of November i.e. 2nd date of planting
could be considered as an effective to minimize early blight disease of potato in Kota zone of
Rajasthan.
Fungicide, Azoxystrobin 23 % SC @ 2 ml/lit per 20 kg of tuber seed treatment
combined with two foliar spray of Azoxystrobin 23 % SC @ 1 ml/lit was recorded maximum
per cent disease control (76.49 %), minimum per cent intensity (6.62 %) with better dry matter
(22.6 %), total number of tubers (548.00 per plot), tuber yield (25.67 t/ha), marketable yield
(21.93 t/ha) with highest net gain of Rs. 67,620.
Among bio-agents i.e. Trichoderma viride @ 8 g/lit per 20 kg of tuber treatment
combined with two foliar spray of T. viride @ 5 g/lit of water was showed maximum per cent
disease control (65.48 %), minimum per cent intensity (9.27 %) with superior dry matter (22.3
%), total number of tubers (485.33 per plot), total yield (22.47 t/ha) and marketable yield (19.10
t/ha) with highest net gain of Rs. 47,712.
Hence, the chemical fungicide Azoxystrobin was found more effective in managing the
disease but due to continuous and irrational use of these chemicals, pathogens have developed
resistance against the fungicides and also aid in environmental pollution and toxicity in the
produce whereas, bio-agents are naturally occurring living organisms, which are found in
rhizosphere, phylloplane, etc. These bio-agents help in not only managing the diseases but also
increasing the crop yield. Hence, application of T. viride @ 8 g/lit per 20 kg of tuber treatment
combined with two foliar spray of T. viride @ 5 g/lit of water could be used in the management
of early blight in potato.
Description
Epidemiology and management of early blight in potato caused by
Alternaria alternate L.