Susceptibility of Jojoba (Simmondsia chinensis) to Verticillium dahliae and to Phymatotrichum omnivorum. T. V. Orum, Laboratory Technician, Department of Plant Pathology, University of Arizona, Tucson 85721. S. M. Alcorn, Professor, T. Herrera-Perez, Former Graduate Student, and G. Miller, Former Undergraduate Student, Department of Plant Pathology, University of Arizona, Tucson 85721. Plant Dis. 65:243-245. . This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1981. DOI: 10.1094/PD-65-243.

Jojoba seedlings through 23 mo of age were susceptible to Verticillium dahliae under greenhouse conditions. Major symptoms associated with infection by V. dahliae included unilateral, marginal chlorosis of leaves and gray-green, wrinkled leaf surfaces. Vascular discoloration was frequently associated and was most obvious at nodes bearing leaves with symptoms. Defoliation and death occurred in some tests. Minimum effective inoculum concentrations for soil drenches contained 5 × 10⁴ conidia per milliliter, but concentrations containing at least 5 × 10⁶ were more effective, with up to 95% of the plants becoming infected. Jojoba plants (at least 3 mo old) also were susceptible to Phymatotrichum omnivorum. Numbers of affected plants varied with soil type and inoculum concentration. Under the most favorable conditions, 16 of 24 plants had rotted roots in 7 wk; five of these died. Strands of P. omnivorum occurred on nonrotted roots of some inoculated plants.

Keyword(s): arid land plants, control, Texas root rot, Verticillium wilt.