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Re: [SANET-MG] copper side effects on soil fungi

I have been interested for a number of years in this subject. At UCD I studied phylloxera damage to grapevine roots in organic and conventionally managed vineyards, and found that the damage is much reduced in organic vineyards. Although phylloxera is an insect (not to be confused with Phytophthera, a fungus) the damage to the roots comes from soil-borne fungal pathogens that enter the phylloxera feeding sites. Phylloxera, which the French had inadvertently brought over to Europe from North America with their samples of North American Vitis species, did great damage to vineyards in Europe in the 1850s to 1870s, causing the death of most. The V. vinifera (European grape) vines were highly susceptible to phylloxera, a North American insect. These vineyards were "organic" except for the fact that they used enormous amounts of Bordeaux mix, a copper-based compound, for fungal disease control. Was this the reason why these "organic" vineyards were so susceptible to phylloxera damage? Were the beneficial fungi, important in suppressing root pathogen fungi, disrupted such that the root pathogens, which may be less susceptible, could flourish? I haven't ever been able to find any data on the levels of residual copper in European vineyard soils in the 1950s when they were still using Bordeaux mix. Don Lotter
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