First Paragraph: This disease, caused by the fungus Phomopsis viticola and long known as "deadarm", first appeared in the American River section of Sacramento County in May 1935. Original reports and descriptions of the disease earlier in the century-especially from the northeast-mistakenly attributed a whole range of symptoms to the one pathogen; it has recently been established that Eutypa armeniacae is responsible for pruning wound cankers and dead arms on vines, whereas P. viticola causes mainly leaf, shoot, and cluster stem spotting.
