Evaluation of plant extracts, fungicides and bio-agents against Fusarium oxysporum f. sp. ciceris under in vitro and field conditions
Evaluation of plant extracts
Among aqueous extracts of 13 plants evaluated at different concentrations, neem leaves’ extract was found to be the most effective in suppressing the mean mycelial growth of
F. oxysporum f. sp.
ciceris by 73.26% followed by datura leaves’ and garlic cloves’ extract (statistically at par). However, the least per cent growth inhibition was recorded in extracts of congress grass, guava and lantana leaves. There was a significant increase in mycelial growth inhibition of the pathogen with increasing concentrations of plant extracts. Maximum mean mycelial growth inhibition of 53.16% was observed at 25% concentration of different plant extracts. The interaction between treatments and concentrations was found to be significant. All the plant extracts inhibited the mycelial growth at 10% concentration, however, the extracts varied with respect to the concentrations up to which the growth inhibition occurred. In leaves extract of chrysanthemum, the growth inhibition was observed up to a concentration of 20% while in remaining plant extracts increase in inhibition continued up to 25%. The per cent growth inhibition was statistically on par at 10 and 15% concentrations in aqueous extract of ginger rhizomes, henna, parthenium and datura leaves and at 15 and 20% concentrations in guava leaves (Table 2).
Under field conditions, seed treatment with extract of neem and datura leaves (statistically at par) were the most effective in curtailing the wilt incidence by 39.02 and 34.14% along with 7.55 and 6.83% enhanced seed yield of chickpea variety JG 62, respectively. Other plant extracts had no significant effect on disease incidence (Table 3). Various antifungal substances produced from plant extracts have been reported to inhibit different pathogens. The results of present study are in conformity with those of
Singh and Chand (2004),
Irum (2007) and
Jamwal et al., (2017) who reported aqueous extract of neem to be effective against
F. oxysporum f. sp.
ciceris. The effectiveness of garlic leaf extract and neem oil against
F. oxysporum f. sp.
ciceris has also been established by
Singh et al., (1979) and
Singh et al., (1980), respectively.
Jespers and Ward (1993) reported that aqueous extract of
Datura metel var.
quinquencuspida at 40% concentration was effective in suppressing the mycelial growth of
F. moniliforme f. sp.
ciceri. However, in present study the aqueous leaves extract of
Datura stramonium suppressed the growth of wilt pathogen by more than 60% at a concentration of 20%. Previous reports have also indicated the toxic effect of extract of garlic bulbs (
Chand and Singh, 2005;
Jamwal et al., 2017), argel, ginger and jatropha
(Mohamed et al., 2016) to
F. oxysporum f. sp
. ciceris. Reduction in disease incidence in aqueous extracts of different plants might be due to their direct toxic effect on mycelial growth of the pathogen.
Evaluation of fungicides
The fungicides namely, hexaconazole 5 EC, azoxystrobin 23 SC, tebuconazole 25 EC, captan 50 WP, mancozeb 75 WP and carbendazim 50 WP differed considerably in their toxicity to mycelial growth of
F. oxysporum f. sp.
ciceris under
in vitro conditions
. The EC50 values of fungicides ranged from 1.28 to 4.79 ppm a.i., while the EC90 varied between 15.24 to 4148.77 ppm a.i. Amongst various fungicides, carbendazim 50 WP proved to be the most toxic fungicide in inhibiting mycelial growth of the fungus with the least EC50 and EC90 values of 1.28 and 15.24 ppm a.i. followed by azoxystrobin 23 SC with EC50 and EC90 values 1.57 and 49.16 ppm a.i., respectively (Table 4). These observations were in agreement with the findings of
Mahmood et al., (2015) and
Jamwal et al., (2017) who reported that carbendazim 50 WP was highly inhibitory to fungal growth of
F. oxysporum f. sp
. ciceris. However,
Mohamed et al., (2016) recorded 95% inhibition of mycelial growth of
F. oxysporum f. sp.
ciceris by thiram followed by bayfedan.
Under field conditions, the disease incidence was significantly reduced by seed treatment with the fungicides during both the years. On mean basis, seed treatment with carbendazim 50 WP and azoxystrobin 23 SC (statistically at par) were superior over other treatments and provided 88.41 and 85.98% reduction in wilt incidence. Mancozeb 75 WP and captan 50 WP were observed to be less effective. The highest seed yield of 1766.40 and 1737.36 kg/ha, respectively was obtained in carbendazim 50 WP and azoxystrobin 23 SC treated plots, which was 12.85 and 10.99% higher than the control (Table 1). Effective management of Fusarium wilt with carbendazim 50 WP has also been documented by several researchers
(Haware et al., 1978; De et al., 1996; Singh and Jha, 2003;
Andrabi et al., 2011; Mahmood et al., 2015).
Evaluation of bio-agents
Out of four bio-agents
viz. T. viride, T. harzianum, G. virens and
P. fluorescens, maximum reduction (75.27%) in mycelial growth of the pathogen was observed with
T. viride followed by
T. harzianum (68.05%) while
P. fluorescens and
G. virens (statistically at par) were found less effective in inhibiting the fungal growth (Table 5).
Trichoderma spp. (
T. harzianum and
T. viride) are well documented for being effective bio-agents against soil-borne fungi namely,
Fusarium,
Pythium and
Rhizoctonia (Papavizas
et al., 1984;
Mohiddin et al., 2010). In present study,
G. virens inhibited mycelial growth of test pathogen by 44.44%, corroborating the results of
Maitlo et al., (2019).
In field tests, all the bio-agents significantly reduced the wilt incidence during both the years. Based on mean of two years’ data, seed treatment with
T. viride and
T. harzianum (statistically at par) gave the best results in reducing the disease incidence followed by
P. fluorescens while seed treatment with
G. virens proved to be less effective.
T. viride and
T. harzianum suppressed the Fusarium wilt by 48.35 and 42.25% along with 6.91 and 6.81% increase in seed yield of chickpea, respectively (Table 6). Soil application of
T. harzianum and
T. viride has been found effective in managing wilt diseases
(Prasad et al., 2002; Dubey et al., 2012). In the present investigation, bio-priming seeds of chickpea variety JG 62 with
T. viride or
T. harzianum provided better disease control along with enhanced seed yield, indicating their possible use in managing chickpea wilt in low-input sustainable agriculture, supporting the findings of
Mane and Yadav (2015) and
Abhiram and Masih (2018).
Trichoderma species have been highlighted as potential bio-agent in controlling Fusarium wilt of chickpea
(Wani et al., 2007; Verma et al., 2014) and were superior to
B. subtilis and a commercial bio-pesticide Kalisena™
(Dubey et al., 2007). Moradi et al., (2012) reported that seed and liquid inoculation of
B. subtilis and
T. harzianum, singly or in combination reduced disease severity substantially up to 40% while
Subhani et al., (2013) reported
T. harzianum followed by
P. fluorescens as an effective bio-agent in curtailing disease incidence by 67.93% under screen house conditions.
