Weedborne Reservoirs and Seed Transmission of Verticillium dahliae in Lettuce

Abstract

The seed transmission of Verticillium dahliae was evaluated in lettuce (Lactuca sativa). Seed collected from lettuce plants infected with V. dahliae were plated with or without surface sterilization on Sorenson's modified NP10 medium. Of the seed plated with or without surface sterilization, 90 and 66%, respectively, yielded colonies of V. dahliae. The incidence of Verticillium wilt ranged from 55 to 80% among lettuce plants grown from seed harvested from infected plants. All evaluated isolates of V. dahliae were capable of seed transmission in lettuce. A V. tricorpus isolate failed to cause significant disease in lettuce or to become seedborne. Storage of contaminated seed at seven temperatures ranging from -20 to 15°C for up to 72 weeks did not reduce the incidence of V. dahliae in seed, whereas storage at room temperature (23 ± 2°C) for 20 to 52 weeks reduced the incidence of V. dahliae without affecting seed viability. Of the 11 weed species collected from fields with a known history of Verticillium wilt of lettuce, four yielded V. dahliae. Pathogenicity tests demonstrated that isolates of V. dahliae from Sonchus oleraceus, Capsella bursa-pastoris, and Solanum sarrachoides were as virulent as or more virulent than an isolate of V. dahliae from lettuce. These results demonstrate the potential of seedborne and weedborne inoculum to disseminate V. dahliae.

Verticillium wilt of olive: a case study to implement an integrated strategy to control a soil-borne pathogen

“…Obviously, a mandatory initial step for an effective VWO control is the implementation of certification programs aimed to produce pathogen-free olive plants (see below). It is also interesting to mention here one study suggesting that V. dahliae seed-transmission can also operate in olive, a situation which has been reported in herbaceous hosts (Toit et al 2005;Vallad et al 2005). Indeed, V. dahliae was detected in olive seeds by PCR-based assays (Karajeh 2006).…”

Relationship between mycelial inoculum of Sclerotinia sclerotiorum and performance of sunflower seeds under controlled condition

“…In terms of diagnosis and management of this disease, that fact is quite relevant as asymptomatic plants in other pathosystems may be infected by their pathogens and that may be the cause of serious consequences for growers (Oren et al, 2003;Vallad et al, 2005). In that direction, further investigation should be conducted for confirmation.…”

Diversity, Pathogenicity, and Management of Verticillium Species

“…The list of the hosts infected by V. dahliae is continually expanding as disease outbreaks on new hosts are identified (16,43). One example of host range expansion occurred in lettuce in coastal California where entire crops have been lost to Verticillium wilt (150,161). The population biology of V. dahliae remains the least understood aspect of this ubiquitous phytopathogen.…”