In autumn 1994, we isolated Phoma lycopersici from brown lesions on tomato leaf, stem and fruit in Takachiho, Miyazaki, Japan. The fungus produced round lesions on tomato leaves, petioles, stems and fruits by artificial inoculations using adult and juvenile plants. In Japan, P. exigua, P. lycopersici and P. destructive have been reported as the pathogen of tomato leaf spot, stem rot and fruit rot, respectively. We propose that P. lycopersici also causes leaf spot and fruit rot of tomato, and that the tomato diseases caused by Phoma species should be called by a unified name

A selection of cucumber mosaic virus (CMV) subgroup I strains originating from Asia and Fny-CMV isolated in USA were studied for their interaction with tomato plants. All strains caused mosaic, fernleaf expression and stunting of tomato plants. Symptom expression was relatively mild after infection with Fny-CMV, T-CMV, Le-CMV and MB-CMV, whereas strains PRC-CMV, NT-CMV and K-CMV caused more severe symptoms. Biologically active clones of NT-CMV RNAs 2 and 3 were generated to construct pseudorecombinant viruses with Fny-CMV to map the symptom determining RNA. The pseudorecombinant FNF-CMV (RNAs 1 and 3 from Fny-CMV, RNA 2 from NT-CMV) showed a similar phenotype on tomatoes to those caused by NT-CMV whereas FFN-CMV (RNAs 1 and 2 from Fny-CMV, RNA 3 from NT-CMV) induced symptoms comparable to Fny-CMV. The data indicate that CMV RNA 2 of NT-CMV is involved in the induction of severe symptoms in tomato plants.

Tomato and melon plants were grown in a greenhouse and irrigated with nutrient solution having an EC of 2 dS m-1 (control treatment) and 4, 6, and 8 dS m-1, produced by adding NaCl to the control nutrient solution. After 84 days, leaf water relations, gas exchange parameters, and ion concentrations, as well as plant growth, were measured. Melon plants showed a greater reduction in shoot weight and leaf area than tomato at the two highest salinity levels used (6 and 8 dS m-1). Net photosynthesis (Pn) in melon plants tended to be lower than in tomato, for all saline treatments tested. Pn was reduced by 32% in melon plants grown in nutrient solution having an EC of 4 dS m-1, relative to control plants, and no further decline occurred at higher EC levels. In tomato plants, the Pn decline occurred at EC of 6 dS m-1, and no further reduction was detected at EC of 8 dS m-1. The significant reductions in Pn corresponded to similar leaf Cl- concentrations (around 409 mmol kg-1 dry weight) in both plant species. Net Pn and stomatal conductance were linearly correlated in both tomato and melon plants, Pn being more sensitive to changes in stomatal conductance (g(s)) in melon than in tomato leaves. The decline in the growth parameters caused by salinity in melon and tomato plants was influenced by other factors in addition to reduction in pN rates. Melon leaves accumulated larger amounts of Cl- than tomato, which caused a greater reduction in growth and a reduction in Pn at lower salinity levels than in tomato plants. These facts indicate that tomato is more salt-tolerant than melon.

Effect of soil solarization on bacterial speck of tomato caused by Pseudomonas syringae pv. tomato were investigated as alternative control method to the using of methyl bromide in nurseries. Soil solarization was found effective until 30 cm depth of soil, disease incidence and disease severity were reduced as 77 and 24 percent, respectively by soil solarization

Trichoderma harzianum isolate T39 and T. virens isolate DAR 74290 were evaluated as potential biological agents for control of pink rot of potato and root and stem rot of tomato caused by Phytophthora erythroseptica. Cell-free metabolites of T. virens DAR 74290 completely inhibited growth of P. erythroseptica in vitro and appeared to be fungicidal. T. virens DAR 74290 and Trichodex, a commercial formulation of T. harzianum T39, were tested for their ability to protect potato and tomato plants from disease caused by P. erythroseptica in glasshouse experiments. Trichodex and T. virens DAR 74290, alone and combined, reduced disease severity in shoots and roots of potatoes 10 weeks after inoculation with the pathogen. The yield of potatoes from plants treated with P. erythroseptica and T. virens DAR 74290 (mean of 12.9g fresh weight/pot) was significantly greater than in controls inoculated with the pathogen alone (mean of 2.1g/pot). Treatment with Trichodex alone increased the yield of tubers compared to the uninoculated controls. T. virens DAR 74290 increased the survival of tomato seedlings inoculated with the pathogen, and both this isolate and Trichodex decreased the severity of disease on tomato.

A ripe fruit rot of tomato (Lycopersicon esculentum) associated with stink bug (Euschistus conspersus) feeding caused extensive losses in the Sacramento Valley of California in 1998.

Severe leaf and stem necrosis caused by Tomato spotted wilt virus (TSWV) is an emerging problem for chilli (Capsicum annuum L.) in Assam. A native chilli variety Krishna P was resistant to TSWV under natural infection. This resistant reaction of Krishna P was verified by employing tests with transmission of virus using sap and thrips (Scirtothrips dorsalis Hood). The variety, Krishna P did not show any sign of the disease. This led to the conclusion that the above variety was resistant to TSWV. The susceptible check LCA 305 developed numerous local lesions on leaves. An integrated management of the disease was tested employing non-chemical method viz. mulching with spent mushroom beds and yellow polyethylene sheets. Chemical control treatments were carbofuran in seed bed, quinalphos, bioneem and malathion as spraying in the main field. Quinalphos could delay the onset of the disease upto 80 days after transplanting as compared to 30 days in control plots. Quinalphos gave significantly higher yield (120.76 q ha-1) and the lowest (20.33%) disease incidence. The two mulches viz. spent mushroom beds and yellow polythene could not reduce the disease when compared to chemical treatments. The maximum incidence of 77.03 per cent disease was seen in untreated check plots.

Muskmelon (Cucumis melo L. var. reliculatus) plants exhibiting a yellow leaf disease have been observed in central Thailand since 1993. The pathogen is transmitted to muskmelon by the whitefly, Bemisia tabaci Genn. Based on leaf yellowing symptoms and whitefly transmission, infection by a geminivirus was suspected.

The insecticidal activities of four surfactants (Cide-kick, Silwet L-77, M-Pede and APSA-80), a dishwashing detergent (New Day), a mineral oil (Sunspray oil), a cotton seed oil and a vegetable oil, alone or in combination, were tested against nymphs of Bemisia argentifolii Bellows & Perring on collards and tomato. Silwet L-77 was more effective (>95% mortality) than Cide-Kick or APSA-80 at rates from 0.25-1.00 g Al litre-1 but caused severe phytotoxicity to tender tomato leaves at all but the lowest rate. New Day dish detergent at 2.0 ml litre-1 caused mortality (95%) comparable to M-Pede insecticide soap at 10-fold greater concentration. A New Day ingredient, cocamide DEA, was considerably more active than the other ingredients or the commercial mixture. Additional surfactants added to Sunspray oil increased efficacy in some treatments, but not others. Toxic responses of 2nd- and 3rd- instar whiteflies to vegetable oil and cotton seed oil at 5.0 and 10.0 ml litre-1 plus 0.4 g AI litre-1 APSA-80 ranged from 22.1 to 79.9% and 66.3-88.7% mortality, respectively. Whitefly mortality was greater on tomato than on collard in six of seven instances when differences between host plants were significant. Our results indicate that these surfactants and oils have good potential for controlling B argentifolii.