The reduction in net photosynthesis caused by tomato russet mite (TRM), Aculops lycopersici (Massee), feeding was measured. A significant relationship between net photosynthesis and mite-days per cm2 of leaflet was observed. Photosynthesis of healthy tomato leaflets did not increase to compensate for photosynthesis reduction in damaged leaflets. Studies suggest that destruction of guard cells and subsequent reduction of leaf gas exchange were responsible for photosynthesis reduction, and that no photosynthesis-reducing phytotoxin is present in TRM saliva.

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Bacterial wilt caused by Pseudomonas solanacearum E.F. Smith is an important disease of potato and tomato in many parts of Ethiopia. Isolates were collected from potato and tomato from eight locations and pathogens were characterized during 1985-1987. Cultural characteristics of 58 isolates on tetrazolium chloride agar medium showed variability in colony size and pigment formation. In contrast, physiological characteristics revealed no differences. All isolates utilized disaccharides - maltose, lactose, and cellobiose - but did not oxidize hexose alcohols - mannitol, sorbitol and dulcitol. Based on these characteristics the isolates were classified as biovar II. Hypersensitivity and pathogenicity tests showed slight differences among isolates. Most isolates caused yellow chlorosis while a few others induced hypersensitive reaction on infiltrated tobacco leaves after 24 h. In a pathogenicity test with five solanaceous hosts, all isolates caused wilting of potato, eggplant, and tomato. In addition, a few isolates also infected tobacco plants slightly but none infected pepper. On the basis of the pathogenicity tests the isolates were classified as race 3, which also corresponded to biovar II of the pathogen.

Bacterial wilt caused by Pseudomonas solanacearum E.F. Smith is an important disease of potato and tomato in many parts of Ethiopia. Isolates were collected from potato and tomato from eight locations and pathogens were characterized during 1985-1987. Cultural characteristics of 58 isolates on tetrazolium chloride agar medium showed variability in colony size and pigment formation. In contrast, physiological characteristics revealed no differences. All isolates utilized disaccharides --maltose, lactose, and cellobiose -- but did not oxidize hexose alcohols -- mannitol, sorbitol, and dulcitol. Based on these characteristics the isolates were classified as biovar II. Hypersensitivity and pathogenicity tests showed slight differences among isolates. Most isolates caused yellow chlorosis while a few others induced hypersensitive reaction on infiltrated tobacco leaves after 24 h. In a pathogenicity test with five solanaceous hosts, all isolates caused wilting of potato, eggplant, and tomato. In addition, a few isolates also infected tobacco plants slightly but none infected pepper. On the basis of the pathogenicity tests the isolates were classified as race 3, which also corresponded to biovar II of the pathogen

Tomato stem canker caused by Alternaria alternata (Fr.) keissler was found from several regions in Korea during the growing seasons of both 1985 and 1986 years. Conidia of the fungus were formed in long chains and measured 13-66x7-17micro m with 1-7 transversal septa and 1-5 longitudinal septa on host plant. Conidia formed on culture media were smaller than those on host tissue. The toxin produced by the pathogen in liquid culture was detected by detached leaf bioassay. The correlation between virulence and toxin productivity of the fungus was discussed. Eight of potential host plants including pepper and 11 tomato cultivars were treated with culture filtrate or partially purified toxin. Toxic symptoms were found on only tomato cultivars susceptible to stem cankers. Partially purified toxin showed a single band on TLC plates and was speculated to be a peptide

Field tests in Maryland and New Jersey were conducted to determine the effectiveness of oxamyl (Vydate 2 liquid [2L]) applied as a transplant drench or as multiple foliar sprays for control of the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), on tomato. Rates of 0.56 or 1.12 kg (AI)/ha applied as a single-treatment drench at transplant or as four or five foliar sprays were effective in reducing the number of CPB and the number of stemmed plants, and it reduced the percentage defoliation caused by CPB. The transplant drench (0.56 and 1.12 kg [AI]/ha) resulted in higher first-pick yields (N.J.) in 1984 and 1985, demonstrating the need to protect young tomato transplants from early-season damage by the CPB. The potential for Vydate 2L as a transplant drench application is discussed.

Surveys conducted during 1986-1988 showed that a strain of tobacco mosaic virus (TMV) was the most frequent virus isolated from red pepper cultivars in Kangwon, Korea. The diseased plants showed first yellow mosaic symptoms followed by mild mosaic, and finally dark greening and leaf curls on leaves. This virus was identical with ordinary strain (OM) or tomato strain (T) in the morphology of the particle, but it caused symptomless infection or mild mosaic symptoms on tobacco (cv. Samsun) and tomato. Although the virus produced local lesions on tobacco (cv. Bright Yellow), it induced yellow mosaic symptoms on Physalis floridana and small local lesions on leaves of Nicotiana glutinosa. This virus serologically different from both TMV-OM and TMV-T, though these viruses had some common antigens. On the basis of symptomatology, reactions of indicator plant and serological relationships, the virus was identified as pepper strain of TMV (TMV-P).

A series of laboratory, greenhouse and field experiments was conducted to determine the effect of ash, Aspergillus niger and animal manure on the mycelial growth, sclerotial body formation, disease development and yield of tomato due to Sclerotium rolfsii, the causal organism of tomato seedling damping-off. In vitro test using modified disc bioassay technique showed that wood ash, A. niger and animal manure from goat, buffalo and chicken significantly reduced the mycelial growth and sclerotial body formation from 98 to 31%. Sclerotial bodies mean diameter was suppressed from 42 to 32%. Pot experiment artificially inoculated with S. rolfsii under greenhouse condition revealed that treatments containing ash, A. niger and animal manure significantly reduced damping-off from 96 to 15%. Chicken manure was comparable to PNCB when applied at 10 g/90 g of soil. Chicken manure treated soil had the lowest viable sclerotia of 4% in contrast to 69.83% viability in PNCB [pentachloronitro-benzene] treated soil. Utilization of ash, animal manure and A. niger in field experiment also gave a highly significant disease reduction from 100 to 61%. Chicken manure applied at 10 t/ha gave a 100% disease suppression. Yield was significantly high in plots treated with chicken manure.