The phytotoxic effects of five fumonisin mycotoxins produced by Fusarium moniliforme, i.e., fumonisin A1 (FA1), A2 (FA2), B1 (FB1), B2 (FB2), and B3 (FB3), together with the aminopolyol hydrolysis products of FB1 and FB2 (AP1 and AP2, respectively) and tricarballylic acid (TCA) were compared with the host-specific phytotoxin TA-toxin (TA) produced by Alternaria alternata f. sp. lycopersici. A leaf assay was performed on detached leaves of the tomato genotypes Asc/Asc (tolerant to TA) and asc/asc (sensitive to TA) at four concentrations (0.1, 1, 10, and 100 micromolar) of each toxin. Seedlings of corn cultivars A1849W and PNR 473 and the two tomato genotypes were also used to assay TA, FB1, FB2, and FB3. The fumonisins caused leaf necrosis identical to that caused by TA and FB1, FB2, FB3, and TA caused significantly (P = 0.01) more necrosis compared with the other metabolites tested. Sterile distilled water (control) and TCA caused no necrosis. Significantly (P = 0.01) more necrosis was observed on the asc/asc genotype compared with the Asc/Asc genotype. There was no significant (P > 0.05) difference between necrosis caused by autoclaved metabolites and that caused by nonautoclaved metabolites. The fumonisins caused dose-dependent reductions in shoot and root length and dry mass of corn and tomato seedlings identical to those caused by TA. The results indicated that TA and FB1 are more phytotoxic to seedlings than are FB2 and FB3. The effects of all four toxins were more pronounced on seedlings of the sensitive tomato genotype asc/asc than on the tolerant genotype Asc/Asc. No significant differences were recorded in the reaction of the two corn cultivars. The structural similarity of the fumonisin B mycotoxins and TA is therefore reflected by their phytotoxicity to detached tomato leaves as well as to corn and tomato seedlings.

The pathogenicity of four race-1 and three race-2 tomato wilt isolates of Verticillium dahliae to tomato, eggplant, tobacco, pepper, French bean and cabbage was investigated. Plants were inoculated without wounding and the symptoms assessed 6 weeks later. Both race-1 and race-2 isolates caused foliar symptoms on the race-1 susceptible tomato cultivar GCR-26 (Ve/Ve) altough these were generally more severe with race-1. All race-2 isolates were significantly more pathogenic than race-1 on the race-1 resistant tomato cultivar GCR-218 (ve/ve), although two of the race-1 isolates caused mild foliar symptoms. None of the race-2 isolates caused stunting of GCR-26 whereas they all caused significant stunting of GCR-218. All isolates reduced dry weight on GCR-26 whereas only race-2 affected GCR-128. All isolates reduced dry weight on GCR-26 whereas only race-2 affected GCR-218. All isolates induced significant foliar symptoms, stunting and reduction in dry weight on eggplant. Only one isolate (race-1) caused foliar symptoms on tobacco but this was not accompanied by a reduction in either plant height or dry weight. All isolates were able to cause foliar symptoms on pepper, and two caused moderate to severe symptoms. Four isolates caused a significant reduction in plant height and one of these reduced dry weight. One isolate which caused mild foliar symptoms on pepper increased host dry weight. No disease symptoms were observed on the non-solanaceous host French bean. All isolates were capable of inducing mild foliar symptoms on cabbage but none caused reductions in either plant height or dry weight. Race-1 and race-2 isolates could only be distinguished on the near-isogenic pair of tomato cultivars

Damping off diseases caused by Sclerotium rolfsii and Rhizoctonia solani and wilt caused by Fusarium spp. in seedlings of pechay, mustard, lettuce, soybean and tomato were shown to be effectively controlled by Trichoderma longibrachiatum under screenhouse condition. Spores of the antagonist can be inoculated in the soil as suspension and as pellets. Mechanism of control is believed to be by outcompetition of the pathogens by the antagonist. Direct parasitism of the pathogens by Trichoderma may be another mechanism of control

The blossom-end scarring of tomato fruit caused by exposure of the plant to cool weather during ovary formation, commonly termed catfacing, can also be induced by GA3 foliar sprays. To determine if GA3 treatment could serve as a cultivar screening tool to identify lines susceptible to the disorder, we compared the catfacing incidence in 14 fresh-market tomato cultivars after GA3 sprays and in nontreated controls in two field experiments. In 1 year, removal of the plant's apex was also imposed. GA3 sprays (22 micromolars twice, applied 1 week apart to tomato seedlings approximately 5 weeks old) increased catfacing incidence in both years and accentuated cultivar differences in the disorder. Topping did not increase catfacing significantly. The cultivars Valerie, Sunrise, and Basketvee were least affected by catfacing in the experiments, while 'Starfire', 'New Yorker', and 'Olympic' had the highest percentage of catfaced fruit. The GA3 screening method shows promise for identifying cultivar differences in susceptibility to blossom-end scarring.

Variation of Sclerotium rolfsii, the causal organism of stem rot, wilting and/or blight of a number of economically important crops was studied. The cultural, morphological and virulence pattern to different crop species of the different isolates of the organism was compared. Attempts to classify the isolates into strains on the basis of aversion or antagonism when paired in cultural media were also made. Differences in cultural and morphological characteristics of the different isolates of S. rolfsii were noted. Srt, an isolate from tomato produced the highest number of sclerotial bodies while SrM isolate produced the least. Very few but big sclerotial bodies were observed from pepper isolate (SrPP) while SrCp produced numerous but small sclerotial bodies. All the ten isolates were pathogenic to mungbean, soybean, cowpea, cotton, pepper, and tomato. Four days after inoculation, two isolates viz., SrCp and Srs caused wilting in peanut while isolates SrCt and SrA caused wilting in wheat. SrCp was considered as the most agressive and the most virulent isolates. It infected all the crop species except wheat four days after inoculation while wilting occurred 6 days after inoculation with the other isolates

It was demonstrated that the identification of bacterial brown rot of potatoes (caused by Pseudomonas solanacearum) by eggplants (Solanum melongena, var. Black Beauty) as indicator plants is similarly effective as the use of tomato plants (Lycopersicon esculentum, var. Moneymaker). In Germany eggplants as indicator plants have anyway to be kept available for the detection of bacterial ring rot of potatoes (Clavibacter michiganensis ssp. sepedonicus) in the official seed health testing.