Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2003
Publication Date: August 9, 2003
Citation: CAVIN, C.A., BRUCKART, W.L. A SPINACH ISOLATE OF COLLETOTRICHUM DEMATIUM FROM THE UNITED STATES AND RISK ASSESSMENT OF C. GLOEOSPORIOIDES FROM RUSSIAN THISTLE IN HUNGARY. Phytopathology. 93:S123. 2003. Technical Abstract: An isolate of C. gloeosporioides (Cg) from Hungary is under evaluation for biological control of Russian thistle (Salsola tragus), a major weed pest of the U.S. This pathogen has been found to infect spinach in containment greenhouse studies. To clarify risk to spinach, studies have been initiated with a U.S. spinach isolate of C. dematium (Cd) as a standard for comparison with infections caused by Cg. Each pathogen has similar moisture and temperature requirements for infection, so comparative inoculations were made with 16-h dew at 25 deg C. Cg damaged S. tragus Type A and not Type B, as expected from earlier studies, and Cg did not affect spinach biomass. Cd, the spinach pathogen, did not affect either type of S. tragus, and it did not reduce spinach biomass. Spinach plants bolted, and it was difficult to assess the effect of either pathogen on spinach. In a current study with conditions favorable for spinach growth (no bolting), disease by Cd on spinach after 2 wk was significant (100% incidence, n = 10, and a mean rating of 1.6 [scale from 0 - 4]), compared to infections by Cg (30% incidence and a mean rating of 0.3).