STUDIES ON SOIL-BORNE DISEASES OF GARLIC IN HIMACHAL PRADESH
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Date
2023-09-22
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UHF,NAUNI
Abstract
ABSTRACT
The present studies entitled, “Studies on soil-borne diseases of garlic in Himachal Pradesh” were
carried out at experimental farm and laboratory of Department of Plant Pathology during 2019-2021, Dr. YS
Parmar University of Horticulture and Forestry, Nauni, Solan (HP). During the surveys of different garlic
growing areas of Solan, Sirmour and Kullu districts of Himachal Pradesh, basal rot showed the maximum
incidence in 2019, 2020 and 2021 with overall mean incidence of 14.71 per cent, 14.68 per cent and 13.76 per
cent, respectively. However, blue mould rot had the minimum incidence in all the three consecutive years with
the overall mean incidence of 3.96 per cent, 3.38 per cent and 3.87 per cent, respectively. The first above ground
symptoms of the basal rot were curving, yellowing, and/or necrosis of leaves beginning at the tips and
progressively developing downward. In white rot, early symptom was white, fluffy mycelial growth on the stem
plate that extended around the base of the bulb and eventually moved up the bulb and inward from storage leaf
to storage leaf. The first symptoms of blue mold rot were pale yellowish blemishes, watery soft spots, or
occasionally a purplish red stain on the scales. In pathogenicity test, case of inoculation by F. oxysporum, the
symptoms of the disease appeared in 23 days after adding mass culture into soil in comparison to clove
inoculation by spore suspension wherein symptoms developed in 36 days. Incorporation of mass culture of S.
cepivorum to the soil resulted in disease development in 26 days, however, addition of sclerotia to the soil took
40 days in disease development. Similarly, inoculation by mass culture of P. allii took 30 days to develop the
disease, whereas, spore suspension showed disease symptoms in 42 days. In disease management studies, foliar
application of resistance inducing chemicals under field conditions i.e. salicylic acid (SA) at 0.015 per cent
concentration showed minimum disease incidence of 24.65 per cent and maximum disease control of 72.27 per
cent. For collection of root endophytes out of three districts, the maximum bacterial endophytic population
(109.00×105 cfu/g roots) was recorded of isolate 4 of Solan district, likewise, maximum fungal endophytic
population (6.00×103 cfu/g roots) was recorded in isolate 6 of Sirmour district. In vitro testing of bacterial root
endophytes showed the maximum mycelial inhibition of 81.02 per cent by isolate 3. However, in vitro testing of
fungal root endophytes revealed the maximum inhibition of 63.79 per cent and minimum mycelial growth of 21
mm by isolate 1. The bacterial root endophyte, Alcaligenes faecalis subsp. phenolicus and fungal root
endophytes were Trichoderma sp. isolate DGGE and Trichoderma simmonsii strain GH-Sj1 were efficacious
under in vitro and pot culture conditions against basal rot of garlic. Evaluation of root endophytes under pot
culture conditions showed that the endophytic suspension of isolate 7 exhibited minimum disease incidence of
15.97 per cent. Trichoderma viride and Bacillus subtilis were found best fungal and bacterial antagonist against
basal rot of garlic under in vitro conditions. Combined application of Alcaligenes faecalis + salicyclic acid + T.
viride was found best to reduce the disease incidence of basal rot of garlic and registered maximum growth and
yield of garlic under field conditions