ARS | Publication request: Host range determination of Colletotrichum gloeosporioides f. sp. salsolae, a biological control agent of tumbleweed: from BLUPs to biomass loss

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: March 25, 2010
Publication Date: June 1, 2010
Citation: Berner, D.K., Cavin, C.A. 2010. Host range determination of Colletotrichum gloeosporioides f. sp. salsolae, a biological control agent of tumbleweed: from BLUPs to biomass loss. Phytopathology. 100:S205.

Technical Abstract: Host range tests were conducted with Colletotrichum gloeosporioides f. sp. salsolae (CGS) in quarantine to determine whether the fungus is safe to release in N. America for biological control of tumbleweed (Salsola tragus L., Chenopodiaceae). Ninety-two accessions were analyzed from 19 families and 10 tribes within the family Chenopodiaceae. Disease reaction data were combined with a relationship matrix derived from internal transcribed spacer DNA sequences and analyzed with mixed model equations to produce Best Linear Unbiased Predictors (BLUPs) for each species. Twenty nine species from 7 closely-related Chenopodiaceae tribes had significant levels of disease severity as indicated by BLUPs. Of the 29 susceptible species, 10 native or commercially important species in N. America were identified as needing additional tests to determine the extent of any damage caused by disease. These additional tests were done by inoculating the non-target species of concern with CGS and weighing oven-dried biomass of shoots and roots of non-inoculated and inoculated plants one month after inoculation. The shoots and roots of each inoculated control plant were scanned and the surface areas determined with image analysis software. The biomass of the shoots and roots of each plant were standardized by dividing the surface area by the corresponding weights to arrive at per gram unit area. Average differences in standardized biomass between inoculated and controls for each plant species were combined with corresponding disease ratings and analyzed by principal component analysis. Results showed that most of the non-target species clustered as not-damaged while the target and several related weedy species were heavily damaged. Three non-target species were moderately damaged, but these species were either perennial or not ecologically sympatric with tumbleweed.