The efficacy of Milsana Ò VP 1999 and 2000 (a formulated plant extract of Reynoutria sachalinensis), known to induce resistance to powdery mildew on cucumbers, was tested against Leveillula taurica (Le´v.) Arn. on greenhouse tomato. In four out of five trials, Milsana Ò achieved a disease reduction ranging from 42.2 to 64.6%. In one trial only, its efficacy was exceptionally low (23%). Application rates and disease pressure proved to be the main factors affecting the level of control. Milsana Ò was significantly less effective than fungicides (alternated DMIs and penconazole) in situ. In contrast, Milsana Ò was equally effective to wettable sulphur indicating that its effect was rather preventive than curative. The level of efficacy achieved by either Milsana Ò or fungicides did not result in a significant increase of yield. Laboratory tests showed that Milsana Ò (VP 1999) had a direct effect on conidial germination. Whether this effect significantly contributes to its field efficacy, remains to be elucidated. Overall, results indicate that Milsana Ò could play an important role in disease management of powdery mildew in organic and low input tomato production.
Currently there is a lack of effective seed treatments for bacterial pathogens, with Cu-based compounds (the only chemical treatments permitted under organic farming standards) only providing partial control. The aim of this study was to quantify the effect of alternative treatments for the control of bacterial canker (Clavibacter michiganensis subsp. michiganensis), a major seed-borne bacterial disease in tomato. Treatments assessed were acidified nitrite (a treatment previously shown to control the seed-borne fungal disease Didymella lycopersici), antagonistic strains of Bacillus spp. and compost extracts, which were not previously evaluated as treatments for seed-borne diseases. Efficacy of treatments was determined in a seed disinfection assay. Ten-minute immersion of seed in 300 mmol l −1 acidified nitrite resulted in 98% being pathogen free. Copper hydroxide, certain strains of Bacillus spp. and all compost extracts resulted in 100% pathogen free seed.
Spores of the hyperparasite Acremonium alternatum reduced powdery mildew infection by Leveillula taurica on greenhouse tomato. The effect was slightly increased when spores were applied killed, and therefore not due to direct parasitism. The effect was systemic, protecting untreated leaves above the treated ones. Spores killed by heat had more effect than when killed by UV, so the effect was presumably due to induction of host resistance by substances released when cells were heat killed. The size of the effect depended upon leaf age and level of infection. Effects on primary infection and expansion of successful infections appear to be under independent control.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.