Recovery of Verticillium dahliae from Weed Plants in Farmers' Fields in Peru. R. Vargas- Machuca, Student, National University of Central Peru, Huancayo. C. Martin, and W. Galindez. Pathologist, Project Leader, and Assistant Pathologist, International Potato Center, Apartado 5969, Lima, Peru. Plant Dis. 71:756-758. Accepted for publication 26 December 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0756.

Sixty-five weed species from fields used in rotation for potato production were collected from 23 fields in 15 localities in the Mantaro Valley (elevation 3,200–4,200 m) in central Peru. Eighteen of the 65 weed species had Verticillium dahliae in their vascular system under natural field conditions. Ten of these did not express any Verticillium wilt symptoms; the other eight showed symptoms of chlorosis in the lower leaves, defoliation, and wilt. Presence or absence of external symptoms in weeds artificially inoculated in the greenhouse agreed with those observed under natural field conditions. Volunteer potato plants were infected with V. dahliae. There was no relationship between altitude and the weed species infected with V. dahliae; the same weed species that are infected with the fungus at the lower agroecological zone (elevation 3,200–3,500 m) also act as a host in the intermediate zone (elevation 3,500–3,800 m). V. dahliae was the only Verticillium species recovered from weed hosts in the Mantaro Valley.