First Report of Verticillium Wilt of Faba Bean Caused by Verticillium dahliae in Spain

Cryptic Infection and Systemic Colonization of Leguminous Crops by Verticillium dahliae, the Cause of Verticillium Wilt

Verticillium dahliae, the cause of Verticillium wilt, is a widespread pathogen that affects many crops in California and throughout the world. Cover cropping with leguminous species is often integrated into a rotation scheme for its contribution to soil nitrogen, and can contribute to management of Verticillium wilt provided the chosen crop does not support development of V. dahliae. Seven cool season legumes (faba bean, bell bean, field pea, hairy vetch, common vetch, purple vetch, and woollypod vetch), and three warm season legumes (sesbania, sunn hemp, and black-eyed pea) were evaluated as hosts for reproductive growth of V. dahliae. All 10 legumes were colonized by V. dahliae, while remaining symptomless, when subjected to a root-dip inoculation. Similar results were obtained when plants were grown in infested potting soil, albeit with a lower frequency of infection than in root-dip assays. All tested legumes were also infected in field trials, with the exception of bell bean. Overall, warm season legumes sustained higher rates of infection than cool season legumes. Common vetch was the most extensively colonized of the cool season legumes. Based on the results of this study, legumes may not be an appropriate rotation crop in fields where Verticillium wilt is a problem.

Verticillium Wilt: A Threat to Artichoke Production

Verticillium wilt is becoming an increasing concern in artichoke production because the rapid spread of the disease to new growing areas has led to declining production. Scientists from Italy, Spain, and the United States combine to bring us up to date on diagnosis of the disease, its epidemiology and life cycle, as well as management strategies, current and forthcoming.

Genetic Diversity and Host Range of Verticillium dahliae Isolates from Artichoke and Other Vegetable Crops in Spain

Artichoke is severely affected by Verticillium wilt, caused by Verticillium dahliae, in eastern-central Spain, which is one of the most important vegetable-cropping areas in the country. To determine genetic and virulence variability in local populations of V. dahliae, 18 isolates collected from artichoke and other vegetable species cultivated in eastern-central Spain were selected to represent local vegetative compatibility groups (VCGs). Diversity in the isolates was characterized by molecular markers and virulence in 12 important hosts for that region. Recently developed microsatellite markers (simple-sequence repeats) and polymorphic sequences were used to assess the genetic variation among those isolates to reveal any association occurring among host source, VCG, and virulence. Although all isolates caused severe disease symptoms on artichoke, cardoon, eggplant, and watermelon, those from artichoke had a limited host range and isolates from watermelon, muskmelon, and eggplant were not pathogenic to some of the hosts tested. VCG diversity was related to differential virulence in certain hosts.