In addition to fungal diseases such as rot and mildew, viral diseases like leafroll and fan-leaf and bacterial infections such as Pierce’s Disease (PD) can cause problems in the vineyard. Viral diseases can decrease yield but will not kill vines, but PD is almost always fatal.
In addition to disease there are a host of pests, some that can be treated and some that cannot. Among the most difficult to treat are phylloxera and nematodes. These are small aphids that infect the roots of the vines, cause damage, and eventually kill the vine. These pests originated in North America, where the indigenous species of vine developed tolerance to them. The fine wine grapes of Europe had not and were thus killed when the pest was introduced into European vineyards during 19th century horticultural experimentation.
Besides phylloxera and nematodes, grape moths and spider mites are common pests that can severely damage vines, but they are much more easily treated. Other pests, such as birds, rabbits and deer consume the fruit and can be difficult to deter.
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