Poltiglia Bordolese

 

Acidic mixtures have a prompt action, but are more likely to be phytotoxic and therefore burn to the affected vegetation, alkaline ones are slow, but more persistent also due to the greater adhesiveness given by the presence of greater quantities of lime. The phytotoxicity of the pulp on vegetation and small fruits, as well as that of cupric analogues, is well known and is expressed in any case with a reduction in vegetative growth and sometimes with burns on the floral organs which make its use inadvisable, apart from cases of indispensability and ascertained reduced varietal sensitivity during flowering. On small apple or pear fruits and on young grapes, the lesions caused by the caustic power of the mixture are reflected in the appearance of rust on the skin which only in the most serious cases can deform the fruit or prevent regular growth. Too hot and dry seasons increase the negative influence of lime on cuticular and stomatal transpiration, accentuating the reduction in vegetation development. The spectrum of activity is very broad: peronospora, anthracnose, black rot, corineo, monilia, fusicocco, rusts, cankers, scab, cylindrosporiosis, septoria, escoriosis, pitting, alternaria, centospora are some of the main fungal agents controlled. Copper then has important secondary actions on powdery mildew, monilia and botrytis, in these cases the action is often not direct on the fungus, but occurs through the thickening of the external film of the plants and their fruits. The bacteriostatic action of coppers is very important, exploited above all to prevent or reduce the spread, since 1997, of fire blight on pome fruit. The doses of Bordeaux mixture can never be standardized as they certainly depend on the seasonal period in which one finds oneself, on the meteorological trend and the vegetative growth of the crop, on the area and on the aggressiveness of the diseases to be fought. During the winter, when the fruit trees are in the resting stage, the mash can be used at a rather high dose, even 1.5 - 2.0 kg per quintal of water, as the wood has good resistance. However, here too variety and species represent a discriminating factor: for example on peach the doses must be lower than on pome fruit. It is best that the temperature does not fall below freezing during distribution and in the following days. If we deal with the problem of downy mildew on the vine, we need to use at least 100 g of copper ion per hl of water

The doses of Bordeaux mixture can never be standardized as they certainly depend on the seasonal period in which one finds oneself, on the meteorological trend and the vegetative growth of the crop, on the area and on the aggressiveness of the diseases to be fought. During the winter, when the fruit trees are in the resting stage, the mash can be used at a rather high dose, even 1.5 - 2.0 kg per quintal of water, as the wood has good resistance. However, here too variety and species represent a discriminating factor: for example on peach the doses must be lower than on pome fruit. It is best that the temperature does not fall below freezing during distribution and in the following days. If we deal with the problem of downy mildew on the vine, we need to use at least 100 g of copper ion per hl of water