Submitted to: XII Biennial Workshop on Smut Fungi Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/16/2002
Publication Date: 6/16/2002
Citation: BONDE, M.R., NESTER, S.E., OLSEN, M., BERNER, D.K. SURVIVAL OF KARNAL BUNT (TILLETIA INDICA) TELIOSPORES IN ARIZONA FIELD SOILS. XIITH BIENNIAL WORKSHOP ON SMUT FUNGI PROCEEDINGS. 2002.
Technical Abstract: When Karnal bunt was first discovered in the southwestern U.S., one of the first pieces of information desired was the longevity of teliospores in contaminated field soil in southwestern U.S. To answer the question, in April 1998 we initiated a teliospore longevity study in Arizona field plots in which artificially infested soil was placed in polyester mesh bags that allowed moisture, but not teliospores, to pass through the 21-mm diameter pores. These bags then were buried at 2-, 10-, and 20-cm depths in irrigated and non-irrigated field plots, or kept dry in plastic bags and maintained at room temperature in the laboratory at Fort Detrick, MD. Over the next 42 months, bags were retrieved and teliospores tested for viability. Two methods were used to test viability. One method determined the total number of viable teliospores (TNVT) in a soil sample, regardless of whether or not teliospores could be extracted from the soil. Based on non-linear regressions of TNVT, the percent viable teliospores decreased from 55.7% at time zero to 11.5% and 6.7% for non-irrigated and irrigated field soil, respectively, after 42 months. TNVT in soil in the laboratory decreased to 33.7%. The second method determined germination percentages of teliospores extracted from the soil samples by means of a modification of the sucrose centrifugation technique. Regression analyses of TNVT accounted for more of the overall variability than analyses of teliospore germination. The results are significant in that they show many teliospores survive at least 42 months in Arizona soils, and that measuring only germinability of those that can be extracted may not provide accurate conclusions.