The Influence of Tillage on Dispersal of Tilletia indica Teliospores from a Concentrated Point Source

A study was conducted to determine the impact of tillage on dispersal of Tilletia indica teliospores from a concentrated point source in Arizona. The infested source was created using a 300-ml teliospore suspension, containing approximately 9.0 × 10 teliospores/ml, sprayed onto a 1-by-3-m soil area. Approximately 400 g of soil was collected before tillage treatments, representing the teliospore baseline, and after each of five disk passes, to an approximate depth of 20 cm, through the infestation source (n = 597). Soil samples were collected along three parallel lines extending from the infested area at increments of 1, 3, or 10 m to a total distance of 10, 30, and 50 m, respectively. Teliospores were recovered from soil samples by a combined size-selective sieving sucrose-centrifugation technique. Immediately following teliospore infestation, an average of 3.6 × 10 teliospores per 25 g of soil sample were recovered from the infestation area. Two different trends in recoverable teliospores occurred at 0- to 10-m sampling distances following five plow passes: either a decrease in the number of teliospores recovered, represented at points 0, 1, and 2 m, or an increase in recoverable teliospores found at points 3 to 10 m. The study was repeated twice for a total of three experiments, and teliospores were recovered to a maximum distance of 24 m. However, the numbers recovered from distances beyond 10 m were sporadic. Based on data from this research, we conclude that teliospores are not distributed in large quantities to great distances by tillage and, therefore, tillage cannot account for the spatial distribution of teliospores in many infested wheat fields.