A causal agent of mosaic disease on tomato was determined by using indicator plants and electron microscopy examination. The results showed that mosaic disease on tomato was caused by Cucumber Mosaic Virus (CMV). Browella sp. and Physalis floridana might be used as new indicator plants for CMV. The symptoms was quite distinct mosaic, malformation and enation.

Chlorotic ringspots or chlorotic leaf specking, terminal bud necrosis, axillary shoot proliferation and severe stunting of groundnut (Arachis hypogaea) were shown to be caused by tomato spotted wilt virus (TSWV). All 28 species of plants tested were susceptible to the virus. Cowpea (Vigna unguiculata cv. C-152) was found to be a good assay host. TSWV remained infective in buffered sap of groundnut at a dilution of 10-2.5, after storage for 4 h at room temperature (30 oC) and for 10 min at 40 but not 45 oC. The haemagglutination test was adapted to detect TSWV in crude extracts of groundnut. Sap from infected groundnut and tomato contained spherical membrane-bound virus particles 70 to 90 nm diameter. The virus was transmitted by thrips (Scirtothrips dorsalis). The prevalence of TSWV in India and the high incidence in groundnut indicates that the virus is economically important

Field experiments to prevent and control the tomato moth (Scrobipalpuloides absoluta (Meyrick)) and tomato early (Alternaria solani) and late (Phytophthora infestans) blights were done on the tomato varieties Duke and Small Fry. The insecticides profenofos, cartap, triflumuron, and permetrin were evaluated to prevent the tomato moth damage to the fruit. The fungicides: mancozeb (80%), mancozeb (64%) + cimoxamilo (8%), mancozeb (48%) + metalaxyl (10%) and mancozeb (20%) + copper (21%) to prevent the tomato blights were also tested. An appropriate level of control of the tomato fruit moth with the insecticides used was obtained, thus increasing the number of fruits good for export. The evaluation of the damage caused by early and late blights under field conditions, showed an adequate level of control of early blight. Late blight was not observed in the field. The post harvest study was done with fruits produced in the previous experiment as well as with fruits of cultivar Cal-Ace used as a known susceptible control. Fruits were treated with the fungicides: mancozeb (80%), carbendazim, dichlofluanid and the wettable agent was done. Fruits showing a maturity stage of breaker were utilized. The fungicide dichlofluanid reduced postharvest fungal rots in the cultivars Duke and Cal-Ace, although the level of control cannot be considered as sufficient to maintain healthy fruits. Cultivar Small Fry's fruits were less damaged by fruit rots than those from Duke and Cal-Ace. The most frequently found fungal genera were: Cladosporium sp., Stemphyllium sp., Alternaria sp., Rhizopus sp. and Penicillium sp., in the same order of occurrence. Cladosporium sp. was more frequently observed on Duke's and Cal-Ace's tomato fruits and Stemphylium sp. was on Cal-Ace's fruits.

Field experiments to prevent and control the tomato moth (Scrobipalpuloides absoluta (Meyrick)) and tomato early (Alternaria solani) and late (Phytophthora infestans) blights were done on the tomato varieties Duke and Small Fry. The insecticides profenofos, cartap, triflumuron, and permetrin were evaluated to prevent the tomato moth damage to the fruit. The fungicides: mancozeb (80%), mancozeb (64%) + cimoxamilo (8%), mancozeb (48%) + metalaxyl (10%) and mancozeb (20%) + copper (21%) to prevent the tomato blights were also tested. An appropriate level of control of the tomato fruit moth with the insecticides used was obtained, thus increasing the number of fruits good for export. The evaluation of the damage caused by early and late blights under field conditions, showed an adequate level of control of early blight. Late blight was not observed in the field. The post harvest study was done with fruits produced in the previous experiment as well as with fruits of cultivar Cal-Ace used as a known susceptible control. Fruits were treated with the fungicides: mancozeb (80%), carbendazim, dichlofluanid and the wettable agent was done. Fruits showing a maturity stage of breaker were utilized. The fungicide dichlofluanid reduced postharvest fungal rots in the cultivars Duke and Cal-Ace, although the level of control cannot be considered as sufficient to maintain healthy fruits. Cultivar Small Fry's fruits were less damaged by fruit rots than those from Duke and Cal-Ace. The most frequently found fungal genera were: Cladosporium sp., Stemphyllium sp., Alternaria sp., Rhizopus sp. and Penicillium sp., in the same order of occurrence. Cladosporium sp. was more frequently observed on Duke's and Cal-Ace's tomato fruits and Stemphylium sp. was on Cal-Ace's fruits

In two sets of greenhouse experiments, the effect of four Na:Ca equivalent ratios (0, 1, 5, and 10) on Phytophthora root rot of tomato was studied at two ionic concentrations (2.5 vs. 25 meq L-1 or 25 vs. 50 meq L-1) of a modified Hoagland's solution. Two weeks after planting, the plants were either kept at the same ionic concentration or were shifted from low to high or high to low concentration, and half of the plants in each treatment were inoculated with zoospores of Phytophthora parasitica. The percentage of root rot was assessed visually 2 wk after inoculation. Root rot severity increased significantly with increasing Na:Ca ratios at ion concentrations of 2.5 and 25 meq L-1 before or after inoculation. Salt stress at 50 meq L-1 before inoculation increased root rot. Salt stress at 50 meq L-1 after inoculation reduced root rot caused by an isolate of P. parasitica originating from nonsaline soil, particularly at higher Na:Ca ratios of 5 and 10. Root rot caused by an isolate originating from saline soil was not reduced. Percentages of motile and germinated zoospores decreased in vitro, and those of encysted and lysed zoospores increased with increasing salt concentrations and Na:Ca ratios. These effects were more pronounced for the isolate from nonsaline soil than for the isolate from saline soil. The isolate from saline soil lost its relative salt tolerance after 2 mo in culture. Inoculation of tomato seedlings with this isolate after 2 mo in culture resulted in root rot severity similar to that caused by the isolate from nonsaline soil when salt stress was applied during and after inoculation.