Studies on Biological Management of Fusarium Wilt of Tomato

Fusarium wilt of tomato is one of the most important diseases worldwide. The present study focused on comparing the efficacy of various control methods including Trichoderma harzianum, garlic extract and fungicide difenoconazole against the pathogen both in vitro and in planta. In a lab experiment, dual culture technique was used to test the efficacy of Trichoderma harzianum on inhibition of the pathogen growth. Garlic extract was tested at concentration of 15 ml/L of potato dextrose agar media while fungicide difenoconazole was used @ 100 ppm. The lowest colony diameter (1.8 cm) was observed when pathogen was grown in dual culture with Trichoderma harzianum. In a screen house experiment, these treatments were tested in planta under inoculated condition. Two weeks after the inoculation, plants were assessed for disease severity through visual observation. Inoculated plants receiving no treatment showed the highest disease severity (71%) while lowest disease severity (8.63%) was observed for bio-control followed by fungicide difenoconazole. Garlic extract proved less effective at concentration tested in this study. Area under disease progress curve was significantly lower for treated plants than inoculated control. A similar trend was evident for yield parameters. There was a strong negative correlation between disease severity and fruit size. A simple linear relationship (R-2 = 0.99) was observed between disease severity and yield. The result indicates significance of the non-chemical control of tomato wilt to minimize the excessive use of fungicides. Work on effective delivery system in field and their efficacy over time is required.