Effects of European and U.S. Strains of Fusarium spp. Pathogenic to Leafy Spurge on North American Grasses and Cultivated Species

Abstract

Abstract:Host-range tests were conducted in a greenhouse using 9 European and 11 U.S. strains of Fusarium spp. pathogenic to Euphorbia spp. Plants of 12 grass species native to the rangelands of North America were raised from seed, planted in soil infested with each strain, and assessed for dry weight after 24 weeks. Five of 11 U.S. strains of Fusarium spp. significantly reduced the dry weight of at least 1 species of grass native to North America. Only 3 native grass species were affected: Idaho fescue (Festuca idahoensis), big bluestem (Andropogon gerardi), and big bluegrass (Poa ampla). Mean reductions ranged from 56 to 92%. A single European strain caused a 53% reduction in dry weight of 1 grass species, sand lovegrass (Eragrostis tichodes). Root-dip assays of 3-week-old seedlings in the greenhouse, with assessment over 3 weeks followed by 9 weeks of further observation and recording of dry weights of surviving plants were used to assess pathogenicity to 27 cultivated plant species. Two of the 3 most virulent U.S. strains failed to cause disease on any crop species according to these criteria. Three U.S. strains were positive in root-dip assays, each to a single crop species, causing vascular discoloration of flax (Linum ussitatissimum) and root necrosis of okra (Hibiscus esculentus) and cotton (Gossypium hirsutum). Neither of the 2 most virulent European strains exhibited pathogenicity to any of 12 crop species. Two other European strains exhibited host ranges comprised of 3 and 4 crop species. Two strains of F. proliferatum from the U.S. and Europe differing in host range were vegetatively compatible. The greater frequency of disease incidence on Euphorbia in Europe and the narrow host range and apparently greater 1

Host range of a deleterious rhizobacterium for biological control of downy brome

“…A successful biocontrol agent must not affect the growth and development of nontarget plants (Boyetchko 1997;Caesar et al 1999;Kennedy and Kremer 1996;Stanley and Julien 1999;Wapshere 1974). Because deleterious rhizobacteria can profoundly affect the growth of certain plant species in the field (Alstrom 1987;Cherrington and Elliott 1987;Fredrickson and Elliott 1985;Loper et al 1985;Suslow and Schroth 1982), the specificity of the plant-suppressive compounds must be determined on a wide range of species prior to commercialization of a microorganism such as P. f. D7.…”

Most Common Fungal Diseases of Globe Artichoke (Cynara scolymus L.) Production Areas

“…Soil and environmental conditions, injured plant roots are an important factor in increasing the disease. Cultural measures in the control against disease; excessive nitrogen applications should be avoided in order to obtain more products, soil disinfection, frequent cultivation and excessive irrigation should not be done, and the selection of disease resistant varieties is important (Beckman 1987;Mariano et al, 1994;Caesar et al, 1999).…”

Interactions of Root-Feeding Insects with Fungal and Oomycete Plant Pathogens

“…Ceutorhynchus assimilis galls are frequently colonized by pathogenic Rhizoctonia and Fusarium spp., suggesting that galling promotes fungal infection ( Caesar et al, 2010 ). Many of the insect and pathogen species associated with rangeland weeds also have narrow host ranges, making them suitable for consideration as biocontrol agents ( Caesar et al, 1999 , 2002 , 2010 ). Synergistic interactions between insects and plant pathogens can enhance weed management and provide an effective alternative to herbicides in multiple plant species.…”