Field evaluation of seed treatment and soil application strategies for managing wilt–dry root rot complex in chickpea

Introduction

Chickpea, Cicer arietinum L. is one of the most important pulse crops of India. In India, chickpea ranks second in area and third in production, perhaps is the largest producer of chickpea in the world covering 80% area and 85% of total production with a productivity of 844 kg per ha (www.iipr.res.in). In Karnataka, it is grown on an area of 1.09 m ha with a production of 0.57 m tonnes and the productivity is 622 kg per ha. Kalaburagi, Bidar, Dharwad, Vijayapur, Gadag, Ballari and Raichur are the major chickpea growing districts. The average production of chickpea is 15 to 20 quintal per hectare which is low in spite of high yielding varieties and new agronomic practices. Plant disease outbreaks are increasing and threaten food security of the world. Global yield losses due to crop pests and diseases on crops are large. Important diseases such as Turcicum leaf blight in maize, downy mildew in sorghum, dry root rot in chickpea, phyllody in chickpea, leaf spots in groundnut, wilt in pigeon pea, necrosis disease in sunflower (Sundaresha et al., 2012) [14] and bud blight caused by Groundnut bud necrosis virus (Balol and Patil, 2014) [2] etc. Bacterial blight in Pomegranate (Basamma et al., 2014) [5] are contributing for the yield loss. The chickpea crop is attacked by 172 pathogens (67 fungi, 22 viruses, 3 bacteria, 80 nematodes and mycoplasma) from all over the world (Nene et al., 1996). Among all, only a few of them have the potential to devastate the crop. Some of the serious diseases in order of their importance are wilt (Fusarium oxysporum f. sp. ciceri) wet root rot (Rhizoctonia solani), dry root rot (Rhizoctonia, bataticola) Ascochyta blight (Ascocthya rabiei), collar rot (Sclerotium rolfsii) and Chickpea rust (Basamma et al., 2021) [4] . Among the several constraints affecting the productivity of chickpea, 10 to 35% loss in yields is due to dry root rot (Mahendra Pal) and 9 to 41% loss due to wilt (Khan et al., 2004) [7] .

For soil borne pathogens, use of fungicide is not practical due to exorbitant cost and environmental hazards involved. Hence integrated management of the disease using bio-control agents and chemicals is the best alternative (Ramarethinum et al., 2001) [12] . Investigations were made in the present study to devise an effective management strategy for wilt/root rot complex of chickpea.

Materials and Methods

An experiment was laid out for the management of chickpea wilt/root rot complex as per randomized block design (RBD) during rabi 2023-24 at experimental block of Regional Agricultural Research Station, Vijayapur. The variety JG -11 was grown and treated with nine treatments which were replicated thrice with plot size of 3 × 4 m 2 and recommended agronomical practices were followed to conduct the experiment. The observations like per cent disease incidence, grain yield and benefit cost ratio were recorded.

Based on observations the disease incidence was calculated by the following formula.

Percent disease incidence = Number of plants infected × 100 Total number of plants examined

Seed yield (q/ha): At the time of harvest, chickpea plants from all the treatments and replications were collected separately. After threshing and winnowing, the net plot yield was recorded and later converted to ha and expressed as q per ha.

Estimation of benefit cost (B:C) ratio:

The economic analysis of the experiment was done by taking into consideration of market prices prevailing during 2023-24 for the produce and cost of treatment. B:C was calculated from gross returns and total cost of cultivation.

Benefit: Cost = Gross returns Total cost of cultivation 2.1. Treatment details 1. T1: Seed Treatment (ST) with T. harzianum @ 10 gm per kg followed by soil drenching with T. harzianum @ 10 g per lt of water to infected and surrounding plants.

2. T2: ST with Thiophanate methyl 45% + Pyraclostrobin 5% FS @ 4 ml per kg followed by soil drenching with T. harzianum @ 10 mg per lt of water to infected and surrounding plants followed by chickpea magic spray at 40 days after sowing 3. T3: ST with Carbendazim 25% + Mancozeb 50% @ 3.5 gm per kg followed by soil drenching with T. harzianum @ 10 g per lt 4. T4: ST with T. harzianum @ 10 gm per kg followed by soil drenching with Thiophanate methyl 45% + Pyraclostrobin 5% FS @ 4 ml of water to infected and surrounding plants followed by chickpea magic spray at 40 days after sowing 5. T5: ST with T. harzianum @ 10 gm per kg followed by soil drenching with Carbendazim 25% + Mancozeb 50% @ 3.5 g per lm 6. T6: ST with Carbendazim 25% + Mancozeb 50% @ 3.5 gm per kg 7. T7: ST with T. harzianum @ 10 gm per kg 8. T8: ST with Thiophanate methyl 45% + Pyraclostrobin 5% FS @ 4 ml per kg followed by chickpea magic spray at 40 days after sowing 9. T9: Control

Results and Discussion

The results of the experiment conducted are presented in the Table 1 and2

Management of chickpea wilt/root rot complex revealed that all the treatments tested were significantly superior over untreated control. Among all the treatments, seed treatment with Thiophanate methyl 45% + Pyraclostrobin 5% FS @ 4 ml per kg followed by soil drenching with T. harzianum @ 10 gm per lt of water to infected and surrounding plants followed by chickpea magic spray at 40 days after sowing (T2) recorded significantly lowest disease incidence of 7.20% with maximum yield of 11.64 q per ha yield from rest of the treatments. The next best treatment was seed treatment with Thiophanate methyl 45% + Pyraclostrobin 5% FS @ 4 ml per kg followed by chickpea magic spray at 40 days after sowing (T8) with 10.01% disease incidence and 10.48 q per ha yield followed by seed treatment with T. harzianum @ 10 g per kg followed by soil drenching with Thiophanate methyl 45% + Pyraclostrobin 5% FS @ 4 ml of water to infected and surrounding plants followed by chickpea magic spray at 40 days after sowing (TT) recorded 12.09 disease incidence and 9.40 q per ha yield, seed treatment with Carbendazim 25% + Mancozeb 50% @ 3.5 gm per kg followed by soil drenching with T. harzianum @ 10 gm per lt (T3) had shown to record 14.32 disease incidence with yield 9.00 q per ha. Significantly highest disease incidene of 26.10% was recorded in control and lowest yield of 5.00 q per ha

Per cent reduction in disease incidence

The maximum reduction in disease incidence (72.41%) was recorded in the treatment combination of seed treatment with Thiophanate methyl 45% + Pyraclostrobin 5% FS @ 4 ml per kg followed by soil drenching with T. harzianum @ 10 gm per lt of water to infected and surrounding plants followed by chickpea magic spray at 40 days after sowing (T2). Seed treatment with Thiophanate methyl 45% + Pyraclostrobin 5% FS @ 4 ml per kg followed by chickpea magic spray at 40 days after sowing (T8) showed per cent reduction of 61.65%. It was comparatively less in other treatments viz., seed treatment with T. harzianum @ 10 gm per kg followed by soil drenching with Thiophanate methyl 45% + Pyraclostrobin 5% FS @ 4 ml of water to infected and surrounding plants followed by chickpea magic spray at 40 days after sowing (T4) (53.63%), seed treatment with Carbendazim 25% + Mancozeb 50% @ 3.5 gm per kg followed by soil drenching with T. harzianum @ 10 gm per lt (T3) (45.13%), seed treatment with T. harzianum @ 10 gm per kg followed by soil drenching with Carbendazim 25% + Mancozeb 50% @ 3.5 gm per lt (T5) (37.28%), seed treatment with Carbendazim 25% + Mancozeb 50% @ 3.5 gm per kg (T6) (29.38%), and seed treatment with T. harzianum @ 10 gm per kg followed by soil drenching with T. harzianum @ 10 gm per lt of water to infected and surrounding plants (T1) (21.53%). The lowest reduction in disease incidence (13.15%) was recorded in seed treatment with T. harzianum @ 10 gm per kg (T7).

Benefit cost ratio (B:C)

The benefit cost ratio of integrated management of chickpea wilt/root rot complex was calculated by considering the total cost of cultivation, cost of treatments and gross returns. The highest benefit (2.48) was recorded in seed treatment with Thiophanate methyl 45% + Pyraclostrobin 5% FS @ 4 ml per kg followed by soil drenching with T. harzianum @ 10 gm per lt of water to infected and surrounding plants followed by chickpea magic spray at 40 days after sowing (T2). The next highest BC ratio (2.26) was recorded in seed treatment with Thiophanate methyl 45% + Pyraclostrobin 5% FS @ 4 ml per kg followed by chickpea magic spray at 40 days after sowing (T8). Least BC ratio of 1.18 was recorded in untreated control. These results are in conformity with Lokesh and Shashidara (2018) [9] who reported that the seed treatment with Thiophanate methyl 45% + Pyraclostrobin 5% FS @ 4 ml per kg + chickpea magic spray 1 ml per lt of water twice at 50% flowering has recorded the least wilt/root rot incidence and highest yield in chickpea. Deepa et al. (2018) [6] also reported that the seed treatment with Carbendazim 25% + Mancozeb 50% @ 3.5 gm per kg followed by soil drenching with the same @ 3 gm per lt water to infected and surrounding plants was effective by recording least incidence and highest seed yield. Kulkarni and Ashtaputre (2020) [8] reported that significantly lower incidence of root rot and wilt in chickpea was recorded in seed treatment with Thiophanate methyl 45% + Pyraclostrobin 5% FS @ 4 ml per kg of seed which was on par with the same @ 5 ml per kg of seed. Singh et al. (2003) [13] reported the efficacy of T. harzianum in controlling R. bataticola causing dry root rot in chickpea under in vitro and in field experiment.

Conclusion

In the integrated management trials of chickpea wilt/root rot complex, seed treatment with Thiophanate methyl 45% + pyraclostrobin 5% FS @ 4 ml per kg followed by soil drenching with T. harzianum @ 10 gm per lt of water to infected and surrounding plants followed by chickpea magic spray at 40 days after sowing was found highly effective by recording least disease incidence of 7.20% with maximum yield of 11.64 q per ha yield and highest benefit ratio (2.48).

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