INTEGRATED DISEASE MANAGEMENT OF FUSARIUM WILT OF TOMATO CAUSED BY Fusarium oxysporum f. sp. lycopersici (Sacc.) Synder and Hansen
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Date
2022-11-06
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PROFESSOR JAYASHANKAR TELANGANA STATE AGRICULTURAL UNIVERSITY
Abstract
Tomato is an important annual vegetable crop and known as poor man’s apple due to availability of vitamin C, minerals (Fe and Cu) and antioxidants. India ranks second to China in growing tomato with an area, production and productivity of 0.789 M ha, 21.24 Mt and 25 Mt ha-1 respectively. In India, tomato is the third important vegetable crop grown after potato and onion. The major tomato growing states in India are Odissa, Madhya Pradesh, Karnataka, Chhattisgarh, Andhra Pradesh and Telangana. In Telangana, tomato is cultivated in an area of 4,148 ha, with production 1171.50 Mt and productivity of 12 mt ha-1 .The major tomato growing districts in Telangana are Adilabad Rangareddy , Sangareddy, etc. Tomato is very often affected by several diseases incited by pathogens such as fungi, bacteria, viruses and nematodes. Among the fungal diseases, Fusarium wilt of tomato caused by Fusarium oxysporum f. sp. lycopersici (Fol), is one of the most destructive diseases across the world causing severe economic losses, wherever tomato is grown.
Roving surveys were conducted in major tomato crop growing areas of Telangana state viz., Adilabad, Sangareddy and Rangareddy during the year 2017- 18 (kharif and rabi). A total of twenty seven villages from three districts were surveyed and recorded the wilt disease incidence ranging from 2.30 to 21. 33 per cent during kharif and 8.6 to 32.60 per cent during rabi, 2017-18. Among the three districts surveyed, Ranga Reddy district recorded maximum mean per cent disease incidence of 13.02 and 28.61 per cent during kharif and rabi, 2017-18, respectively.
Fifteen isolates of Fusarium oxysporum f. sp. lycopersici collected from different tomato growing areas of Telangana were studied for their cultural, morphological, pathogenic and molecular variability. All the isolates showed wide variation in respect of mycelial colour and pigmentation, growth pattern, colony diameter, size and number of
septations of macro and micro conidia and sporulation. Based on pigmentation, Fol isolates were categorized into 4 groups.
Pathogenic variability studies revealed that Isolate Fol - 4, collected from Adilabad district was found to be more virulent in causing disease incidence and disease severity when inoculated to susceptible tomato cv. Pusa Ruby. Further, all the fifteen isolates were characterized at molecular level with species specific primer ITS 1( 5’TCCGTAGGTGAACCTGCGG-3′ ) and ITS 4 (5’-TCCTCCGCTTATTGATATGC-3′) and by using ISSR primers which revealed the relationship among the fifteen isolates with varied degree of coefficient.
The most feasible method for managing Fusarium wilt disease of tomato is by growing resistant cultivars along with usage of effective fungicides. Twenty five germplasm lines were screened against Fol-4 under sick soil conditions and none of them were found to be resistant against Fusarium wilt disease especially at advanced age of the plant. Only six germplasm (EC 914 - 087, 088, 090, 100, 107, and 108) exhibited moderately susceptible reaction and seventeen germplasm as susceptible whereas, two germplasm were highly susceptible.
Chemical methods i.e., fungicides with different mode of action were tested under in vitro conditions against Fol, which is the most effective method in managing the disease. It was found that (tebuconazole + trifloxystrobin) at 1000 ppm was very effective in inhibiting the radial growth of the Fol which was further tested at field level. Among the bio agents screened against Fol under in vitro conditions, Trichoderma viride (Tv 2) was found to be very effective in inhibiting the radial growth of the Fol., which was further evaluated under field conditions.
A field experiment was conducted during rabi, 2018-19 and kharif, 2019-20 to evaluate the best integrated disease management strategies against the Fusarium wilt disease of tomato. The results revealed that among the different integrated disease management strategies comprising of fourteen treatments, integration of cultural (Soil application of neem cake @ 250 kg ha -1 + FYM @ 1000 kg ha -1) + chemical method (foliar application and soil drenching with (tebuconazole + trifloxystrobin) @ 0.1 per cent and biological method (soil application of Trichoderma viride (Tv2) @ 10 kg ha-1 was found to be effective in managing the Fusarium wilt incidence in the both the seasons, which recorded lowest disease incidence of 8.00 per cent and the highest yield of 31.53 t ha-1 with C : B ratio 1: 2.30 during rabi, 2018-19 and 6.66 per cent disease incidence with 30.60 t ha-1with C: B ratio of 1 :2.22 during kharif, 2019-20.
Under the best disease management module tested at field level, it was found that integrating with cultural, chemical and biological methods had effectively managed the Fusarium wilt disease which can be recommended to the farming community.
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D10,649