Ecofriendly management of bacterial wilt of tomato
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Date
2022-09-23
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Publisher
palampur
Abstract
Bacterial wilt is a major hindrance to the production of solanaceous crops in both tropical
and temperate regions of world and it causes substantial yield losses in tomato. The investigation on
“Ecofriendly management of bacterial wilt of tomato” was undertaken during 2021-22 in the
Department of Plant Pathology, CSK HPKV, Palampur. Systematic surveys were conducted in 9
districts of Himachal Pradesh for the prevalence of bacterial wilt in tomato. The highest wilt incidence
(90-100%) was recorded at Solan, Shimla and Kangra districts. A total of 70 PGPR isolates were
obtained from the wilt affected fields and after biochemical testing, the isolates were designated as Pf
(P. fluorescens) and Bc (Bacillus spp.). R. solanacearum was isolated on TZC agar and identified with
the help of biochemical tests. All the PGPR isolates were subjected to in vitro laboratory assay and 6
potential PGPR were found effective against R. solanacearum which showed inhibition zone of 9.53 to
14.73 mm. The effect of potential PGPR on growth parameters viz., root length, shoot length, vigor
index and seed germination were studied and it was found that all of them significantly improved
growth parameters as compared to control. Maximum seed germination (94.60%) was recorded in seed
bacterization with Pseudomonas isolate Pf 22 followed by 93.50 per cent in Bacillus isolate Bc 17. The
isolate Pf 22 showed minimum wilt incidence (51.8%) followed by Bc 17 (56.9%). Commercial
Trichoderma formulations were also evaluated and it was found that inhibition zone varied from 10.74
to 12.56 mm. Maximum shoot length, root length and vigor index was observed in seed treatment with
Trichoshield (T. harzianum) followed by Guard TH (T. harzianum). Seed germination (92.05%) was
significantly higher in seed treatment with Trichoshield. Highest disease control (41.14%) was noted in
seed treatment with Trichoshield followed by Guard TH (38.27%). Combined effect of potential PGPR
and commercial Trichoderma formulations on shoot length, root length and vigor index were studied
using roll towel method. Combination treatments gave significantly enhanced results as compared to
individual treatment of PGPR and commercial Trichoderma formulations. Maximum shoot length, root
length and vigor index were observed in combined treatment with Pseudomonas isolate Pf 22 and
commercial Trichoderma formulation Trichoshield followed by Pf 22 and Guard TH. Maximum
germination was observed in Pf 22 + Trichoshield (95.72%) followed by Pf 22 + Guard TH (94.58%)
as compared to control (81.50%). In pot experiment, lowest wilt incidence was observed in combined
treatment of seed with Pf 22 + Trichoshield (47.94%) and resulted in 48.67 per cent protection against
bacterial wilt. This study indicated the potential benefits of using combined treatments of PGPR and
commercial Trichoderma formulations which effectively enhanced plant growth and suppression of
pathogen