The root-knot nematodes (Meloidogyne spp) are difficult to manage once established in the field because of their wide host range, and soilborne nature. Thus, the aim of the present study was to examine the use of resistant root stock of wild brinjal (Solanum sisymbriifolium) to reduce the loss caused by the nematodes on tomato. For the management of root-knot nematodes, grafted plant with resistant root stock of the wild brinjal was tested under farmers' field conditions at Hemza of Kaski district. Grafted and non-grafted plants were produced in root-knot nematode-free soil. Around three week-old grafted and non-grafted tomato plants were transplanted in four different plastic tunnels where root-knot nematodes had been reported previously. The plants were planted in diagonal position to each other as a pair plot in 80 × 60 cm 2 spacing in an average of 20 × 7 m 2 plastic tunnels. Galling Index (GI) was recorded three times in five randomly selected plants in each plot at 60 days intervals. The first observation was recorded two months after transplanting. Total fruit yield was recorded from same plants. In the grafted plants, the root system was totally free from gall whereas in an average of 7.5 GI in 0-10 scale was recorded in the non-grafted plants. Fruits were harvested from time to time and cumulated after final harvest to calculate the total fruit yield. It was estimated that on an average tomato fruit yield was significantly (P>0.05) increased by 37 percent in the grafted plants compared with the non-grafted plants. Grafting technology could be used effectively for cultivation of commonly grown varieties, which are susceptible to root-knot nematodes in disease prone areas. This can be used as an alternative technology for reducing the use of hazardous pesticides for enhancing commercial organic tomato production. Keywords

Bacterial wilt caused by Ralstonia solanacearum E.F. Smith is one of the destructive diseases of solanaceous vegetables specially tomato (Lycopersicon esculentum L.) and eggplant (Solanum melongena L.). Experiments were conducted to determine biovar types existing among the strains or isolates of Nepal and variation in virulence in some vegetables belonging to solanaceae family. A total of 39 isolates infecting tomato, eggplant, chilli and potato collected from different parts of Nepal were analyzed for biovar types on the basis of 3 disaccharides and 3 hexose alcohols oxidation test. Experiments were conducted to determine variation in virulence or aggressiveness of some of the isolates under screen house conditions using three host differentials such as Pusa Ruby (susceptible), Bishesh (moderately resistant) and Srijana (resistant) tomato cultivars. Of the 39 isolates, 23 were biovar III, three biovar II, three biovar IV, and one was biovar I. Nine isolates could not be differentiated into any of the five biovars. For breeding and epidemiological purposes it is very important to analyze the variability of aggressiveness. A total of 5 isolates collected from different places were included in the test. Isolates from Bhaktapur was found the most virulent causing wilt in the variety Bishesh (moderately resistant). Other isolates had the negative impact with zero wilt on the differentials used. Isolates from Jungekhola of Dhading district did not induce wilt even on susceptible variety (Pusa Ruby), but exhibited only senescence reaction. The result indicated that there is some slight variation among the isolates tested. Some effective management tactics might be needed in those locations where highly aggressive or virulent strain of bacterial wilt is prevalent, because resistant variety may not be stable in such locations.

Cultivation of brassica vegetables has the highest potential for generating income among more traditional rice and maize farmers in Nepal. Among brassica vegetables, the most important are cauliflower (Brassica oleracea var. botrytis L.) and cabbage (B. oleracea var. capitata L.). Although clubroot disease, caused by Plasmodiophora brassicae Woronin, has been observed in Nepal since 1993, severe and widespread epidemics have been observed since 2004 in the Bhaktapur, Kathmandu, Lalitpur, and Palung Valley production areas. Typical disease symptoms (1) are widespread, and disease severity has been particularly severe in the Kathmandu Valley and Palung/Daman area of the Makwanpur District. Many cauliflower fields in these areas have had as much as 100% yield loss between 2004 and 2006 with an estimated 40% overall loss from clubroot. Estimates from interviews with growers in the Palung production area during an intensive farmers' interaction program indicated that cauliflower production was reduced from 5 to 6 metric tons per household (1,500 m2) prior to 2004 to <300 kg per household in 2004 and beyond. The economic loss in this area alone was estimated at $1.4 million in 2004 and 2005. Examination of transplant nurseries indicated that frequently >80% of the seedlings have symptoms of clubroot at the time of transplanting. Soil samples from throughout the production areas indicated that the sandy loam soils were predominately acidic (pH range of 4.2 to 7.2 with >90% below 6.0). Several management practices are being employed to reduce disease severity, including the use of clubroot resistant cultivars, raising the soil pH to >7.0 by using dolomitic lime, testing of the fungicide flusulfamide (Nebijin) and biopesticide Sanjeevani (Trichoderma viride), and biofumigation and solarization of the nursery beds in an effort to reduce disease pressure on transplant material. References: (1) G. R. Dixon. Compendium of Brassica Diseases. S. R. Rimmer et al., eds. American Phytopathological Society, St. Paul, 2007.

DOI: 10.3126/narj.v6i0.3372Nepal Agriculture Research Journal Vol.6 2005 pp.110-111

Bacterial wilt caused by Ralstonia solanacearum E.F. Smith is one of the destructive diseases of tomato. Experiments were conducted to confirm the resistance and to evaluate varieties received from Asian Vegetable Research and Development Center against bacterial wilt disease in the farmers' bacterial wilt sick fields at Thaiba and at Panchkhal during 1999 and 2000-2001 respectively. A total of five varieties such as CLN 2026 C, CLN 2026 D, CLN 1466 J, CLN 1466 P and susceptible check Lapsigede or L 390 were included in the experiments. Randomized complete block design with 4 replications was commenced at both the locations. In terms of disease incidence and yield parameters as well as consumers' preference on the fruit size, CLN 2026 C was found the best variety followed by CLN 2026 D. Wilt incidence was significantly lower in those varieties showing resistant reaction than in susceptible check. However, the marketable fruit yields were significantly higher with low wilt incidences in CLN 1466 P and CLN 1466 J also compared to susceptible check. But the large fruit size of those varieties was not acceptable to the consumers and the growers. Thus, CLN 2026 C and CLN 2026 D could be used as resistant variety to minimize crop losses from bacterial wilt disease.