Environmental Therapy for Pierce’s Disease of Grapevines. Alex H. Purcell, Department of Entomological Sciences, University of California, Berkeley 94720. Plant Dis. 64:388-390. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-388.

The hypothesis that cold climates are therapeutic for Pierce’s disease was tested by overwintering diseased grapevines at Prosser, Washington, and at four sites at different altitudes in California. None of the surviving vines at Prosser, which had the coldest winter, developed symptoms after 6 mo in a greenhouse. At California sites, most of the diseased vines at Blodgett but few vines exposed to the moderate climate at Berkeley recovered from Pierce’s disease. However, recovery rates at Blue Canyon and Coloma, which had lower minimum temperatures than those at Blodgett, were inconsistent with the hypothesis.

Keyword(s): epidemiology.