Development and evaluation of a warning model for the optimal use of copper in organic viticulture.
Downy mildew caused by Plasmopara viticola is one of the most serious diseases affecting grapevine worldwide, and can significantly affect crop quality and quantity. In organic viticulture, downy mildew control is mainly based on copper compounds, which are toxic to organisms in the soil. For this reason, restrictions concerning the maximum amount of copper that organic growers can apply per hectare have been enacted in several countries. We have developed a warning model and a decision-making procedure to help organic grapevine growers optimize their use of copper against downy mildew. This system is based on treating vines with a variable rate of copper when there is an immediate risk of infection and the vegetation is not sufficiently protected by previous treatments. In 2007, the warning model and the decision-making procedure were tested in two vineyards in northern Italy and compared with the local common practice and an untreated control. The treatment timings and copper application rates recommended by the system resulted in control of downy mildew equivalent to that associated with the common practice, but with a considerable reduction in the total amount of copper applied.
Review of impacts on soil biota caused by copper residues from fungicide application
Unlike most other agricultural chemicals, a significant weight of evidence exists that copper based fungicides have a long-term impact on a wide range of soil biota. Effects can occur at relatively low Cu concentrations and influence a number of soil processes including microbial activity, earthworm activity and bioturbation. In most soils, copper residues are likely to remain indefinitely, and will continue to influence the health of the soil. This manuscript reviews Australian and International data on the effects of copper based fungicides on soil health, and the implications for future land management.
Optimal Combination and Concentration of Antibiotics in Media for Isolation of Pathogenic Fungi and Nocardia asteroides
Strains of Blastomyces dermatitidis, Sporothrix schenckii, Histoplasma capsulatum, Cryptococcus neoformans, Nocardia asteroides, and Coccidioides immitis were tested for in vitro susceptibility to polymyxin, gentamicin, kanamycin, chloramphenicol, and neomycin at concentrations of 1, 2, 4, 8, and 16 μg/ml. Polymyxin was the most inhibitory and gentamicin was the least inhibitory of the five antibiotics. Two Histoplasma mycelial strains were partially inhibited by 2 and 8 μg of gentamicin per ml and showed at least a 2+ growth at the higher antibiotic concentration. Kanamycin and neomycin produced significant inhibition of N. asteroides but otherwise were noninhibitory. A combination of chloramphenicol and kanamycin, each at 16 μg/ml, and gentamicin, at 4 μg/ml, was noninhibitory to the strains tested except for N. asteroides. Chloramphenicol at 16 μg/ml was not inhibitory for N. asteroides. The results suggest that the optimal antibiotic combination to use in the isolation of fungi and higher bacteria is chloramphenicol, 16 μg/ml, and gentamicin, 4 μg/ml. Addition of sheep blood (5%) had no effect on antibiotic susceptibility of the organisms studied.