Varietal screening of tomato against bacterial wilt disease under subtropical humid climate of Tripura

Resistance to bacterial wilt of tomato disease incited by Ralstonia solanacearum (Smith) is rarely observed. To identify the resistant sources against disease few tomato varieties and hybrids were screened in naturally infested farmers fields at five different locations viz Sonatola, Kamalnagar, Mahabir Chowmohini, Bhabatoshpara and Uttar Chebri in November 2008. Observations on per cent plant mortality were recorded starting from 15 days of transplanting till final harvest at an interval of 10 days. The plants showing symptoms were examined using ooze test to confirm the disease. The extent of damage to the vascular tissues was reflected in the severity of bacterial wilt which was assessed in all the cultivars and expressed as vascular bundle discolouration index (VBDI). The variety All Rounder was recorded as resistant with a mortality of 8.98 per cent with lowest VBDI (1.0) towards the disease. Four tomato varieties viz Swarakhsha, Rakshak, Trishul and Arka Alok were recorded as moderately resistant (>10 – 20% mortality). Varieties Yash F ₁ Hybrid, TO 1458, Hybrid 7610 and F₁ Amulya 1744 were found moderately susceptible (>30 – 70% mortality) and the VBDI recorded were 2.6, 2.9, 2.7 and 2.8 respectively. Loknath and Arka Vikash were found highly susceptible (>70 – 100% mortality) with highest VBDI of 4 and 4.5 per cent respectively.