Integrated disease management of Fusarium wilt (Fusarium oxysporum F SP lini) of linseed

Introduction

Linseed (Linum usitatissium L.) is one of most important species among oilseed crops. Linum usitatissimum, the specific name for flax within the family Linaceae, aptly describes its usefulness and versatility. In fact, the name Linum originated from the Celtic word lin or "thread," and the name usitatissimum is Latin for "most useful" (Kolodziejczyk and Fedec 1995) [6] . Linseed is one of the oldest crop cultivated for its seeds and fiber. The two products of seed are linseed oil and linseed meal. It is such a valuable crop that every part of the plant has specific economic importance. Linseed is a plant source of high nutritional value, containing 30-45% oil, omega-3 fatty acids, especially high levels of alpha-linolenic acid (ALA), 20-25% protein, and rich dietary fiber (28-30%) (Goyal et al., 2022) [5] . during 2023-24, a total of 1.67 lakh tonnes of linseed was produced in India from an area of 2.39 lakh ha with an average productivity of 698 kg/ha. Madhya Pradesh, Jharkhand and Uttar Pradesh are three major linseed growing states accounting for 78% of area and 79% of production, respectively. In terms of productivity, Rajasthan stands first (1072 kg/ha) followed by Bihar (851 kg/ha) and Nagaland (771 kg/ha) (Linseed, Annual report 2023-24). The crop has been suffering from many abiotic and biotic stresses and among biotic stresses diseases are major limitations. Among the different diseases, major diseases include Fusarium wilt (Fusarium oxysporum f.sp. lini), rust (Melampsora lini), powdery mildew (Oidium lini), Alternaria blight (Altenaria linicola), foot rot (Rhizoctonia solani, Pythium spp.), and damping off of Seedlings (Pythium spp.), etc. Wilt caused by Fusarium oxysporum f. sp. lini is a severe barrier to linseed industry output and productivity (Singh et al., 2021) [8] . The crop loss due to linseed wilt incited by Fusarium oxysporum f. sp. lini is the most destructive disease (Sattar and Hafiz (1952) reported to 80% loss under favourable conditions. It is seed and soil borne pathogen. Management of soil borne disease by single approach is difficult, uneconomical and integrated approach is the best way. Biological control is environment friendly and most accepted method used to control Fusarium oxysporum (Anjajah et al. 2003). Fungicides were used as seed treatment for seed borne diseases, as it eradicates the seed borne inoculums. For development of an integrated disease management strategies, it is essential to use compatible bio agents and fungicides for effective disease management. Soil amendments and specific bio-control agents such as Trichoderma, Pseudomonas, and Bacillus etc. also incorporated in IDM which has capability to suppress soilborne pathogens through manipulation of the physicochemical and microbiological environment. Hence, the present research was carried out to select promised and compatible bio agents for field evaluation for management of Fusarium wilt.

Materials and methods

This experiment was conducted at laboratory Plant Pathology Section, College of Agriculture, Nagpur. In order to find out a suitable fungicide for management of wilt of sslinseed, eight Systemic fungicides (at the concentration of 500, 1000 and 1500 ppm) along with control were assessed by poisoned food technique under in vitro condition as described by (Pennycook and Corbin, 1970). Required quantity of individual fungicide was added separately into sterilized molten and cooled PDA so as to get the desired concentrations of the fungicide. After though mixing twenty ml of the poisoned media was poured into sterilized Petri plates. Mycelial discs of five mm size of the test pathogen were cut with sterile cork borer from the periphery of an actively growing four day old cultures and one such disc was placed at the centre of each plate containing poisoned media. Control treatment was maintained without adding any fungicide to the medium. There were three Petriplate / replication / treatment. Then such plates were incubated at 25 ± 20C. Radial growth of Fusarium oxysporum f. sp. lini was measured when test fungus attained maximum growth in the control plates. The efficacy of the fungicide was expressed as per cent inhibition of mycelial growth over control which was calculated by using the formula given by Vincent (1947).

Per cent Inhibition = C -T × 100 C Where, C = Growth of the test fungus in untreated control plates T = Growth of the test fungus in treated plates

Results and Discussions

In vitro evaluation of fungicides against Fusarium oxysporum f. sp. Lini Mycelial growth Results (Table 3, PLATE 1 and Fig. 1) revealed revealed that all the treatments were significantly greater over control in terms of inhibition of pathogen growth after 7 days of inoculation, that all eight fungicides tested shown wide range of effect on radial mycelial growth of Fusarium oxysporum f. sp.

Mycelial growth inhibition

Results (Table 3, PLATE 1 and fig 1) revealed that all the systemic fungicides tested (each @ 500, 1000 and 1500 ppm) significantly inhibited mycelial growth of Fusarium oxysporum f.sp. lini, over untreated control. Further, per cent mycelial inhibition was increased with increase in concentration of the fungicides. Among all the fungicides evaluated against Fusarium oxysporum f. sp. The result in the study shown that the effect of concentration level (ppm) of fungicides on growth of mycelium, it was recorded that increase in concentration level of fungicides decrease the growth of mycelium. Thus, all the fungicides evaluated were shown fungistatic reaction against test pathogen and significantly inhibited mycelial growth, over untreated control. However, the fungicides found most effective in the order of merit were Carbendazim, Tebuconazole + Trifloxystrobin, Thiophanate methyl, Thiophanate methyl + Pyraclostrobin. Arun and Choudhary (2015) [3] tested seven fungicides invitro against Fusarium oxysporum f. lini, carbendazim 50WP and benlate 50WP were found most effective in checking the colony growth to 00 mm (completely check) Golakiya et al. (2018) [4] Reported that efficacy of six commonly used systemic fungicides viz., azoxystrobin, fosetyl-Al, tebuconazole, thiophanate methyl, carbendazim and flusilazole were evaluated against F. oxysporum f. sp. ciceri at different concentrations viz., 100, 250 and 500 ppm using poisoned food technique and revealed that among all the systemic fungicides at all the concentrations, that maximum mean per cent inhibition of F. oxysporum f. sp. ciceri mycelial growth was recorded in tebuconazole (99.98%) followed by carbendazim (85.03%). Saravanakumari et al. (2019) [7] similar results were observed by carbendazim, mancozeb (63%) + carbendazim (12%) and mancozeb gave complete growth inhibition of the fungus at 500 ppm concentration followed by trifloxystrobin (25%) + tebuconazole (50%) which showed complete mycelial growth inhibition at 1000, 1500 and 2000 ppm concentrations. Tebuconazole, hexaconazole and copper oxychloride were observed as moderate inhibitors of the mycelial growth at 500, 1000, 1500 and 2000 ppm. Minimum inhibition was recorded in benomyl, captan and zineb (64%) + hexaconazole (4%) at -500, 1000, 1500 and 2000 ppm.

Table 3:

In-vitro efficacy of various fungicides against mycelial growth and inhibition of Fusarium oxysporum f. sp. Lin

Tr.

No. Treatments

Colony Diameter *(mm) Percent Inhibition @ PPM 500 ppm 1000 ppm 1500 ppm 500 ppm 1000 ppm 1500 ppm 3rd 5th 7th 3rd 5th 7th 3rd 5th 7th 3rd 5th 7th 3rd 5th 7th 3rd 5th 7th T1 Carbendazim 50% WP 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.0 100.0 100.0 100.00 100.0 100.0 100.0 100.00 100.00

Conclusion

In-vitro efficacy of all the fungicides, evaluated against Fusarium oxysporum f. sp. lini were found fungistatic. However, in systemic fungicide Carbendazim showed 100 per cent inhibition of growth, followed by Tebuconazole + Trifloxystrobin, Thiophanate methyl. In case of field experiment (In-vivo) on integrated disease management strategies during rabi 2022-23 and 2023-24, seed treatment with Mancozeb 25% + Carbendazim 50% WP + soil application T.harzianum with FYM could be recommended for effective management of Fusarium oxysporum f. sp. lini caused linseed wilt based on per cent reduction of disease and highest yield.

Acknowledgement

Acknowledgement I am thankful to my guide Dr. R. W. Ingle for constant support and also grateful to the Head of the Plant Pathology section, College of Agriculture, Nagpur for providing all the necessary facilities for conducting the research work.

References

1. All India Coordinated Research Project on Oilseeds - Linseed. (2023). Annual report 2022-23. ICARDirectorate of Rapeseed-Mustard Research.
2. All India Coordinated Research Project on Oilseeds - Linseed. (2024). Annual report 2023-24. ICARDirectorate of Rapeseed-Mustard Research.
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