Phytopathology (1996) 86, p. S95 (Caesar)

A.J. Caesar (1996)
Effects on native grasses of Rhizoctonia solani and Fusarium spp. pathogenic to leafy spurge, and assessments of host range of Fusarium spp. on 27 cultivated species

Phytopathology 86 (11 suppl.), S95-S95
Abstract: Strains of Rhizoctonia solani and Fusarium spp. have been isolated from diseased leafy spurge (an exotic perennial weed infesting over five million acres in the Northern Plains of the U.S.), and are associated with stand declines of spurge. They may be especially effective when combined with root-attacking insect biological control agents. Furthermore, field applications of these two pathogens as granular formulations have reduced stand density of leafy spurge alone or in combinations. To assess the effects of these two pathogens on native grasses, the major nontarget plant species of economic importance that could be affected by the use of these pathogens, greenhouse host range tests were conducted. Host range testing of Fusarium spp. was also conducted on 27 cultivated species. Fusarium spp. were narrow in host range, based on the root dip assay of 27 cultivated species, but a few strains were capable of reducing dry weight of tomato, safflower, mung bean, sugarbeet, and zinnia. When plugs of native grasses were transplanted into soil infested with Rhizoctonia, no strains caused a significant reduction in dry weight of any of 12 grass species. Fusarium strains exhibited variable host ranges, with the tall warm season grass big bluestem most affected overall. No single strain of Rhizoctonia or Fusarium pathogenic to leafy spurge was detrimental to a broad range of native grass species. The collective results indicate that soilbome plant pathogens may be effective biological control agents that can reduce spurge infestation density without affecting native grasses.
Database assignments for author(s): Anthony J. Caesar

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Euphorbia virgata (weed)