Long-Ranged Movement of
Fusarium graminearum
Elson Shields
Department of Entomology
Cornell University
Ithaca, NY
 Elson Shields (foreground) & son, working hard |
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Long-Ranged Movement of Fusarium graminearum (G. C. Bergstrom, S. L. Maldon, & E. J. Shields)
1997 Aerial spore traps were constructed from plastic soda bottles and carried aloft under the wing of an 8 ft radio controlled airplane to altitudes ranging from 75 ft to 400 ft depending on sampling location. A standard sized petri plate filled with selective media was mounted vertically within the trap and air flow across the plate was controlled with a remotely controlled door in the front of the trap. Upon reaching the desired altitude, the door on the front of the trap was opened and the sample was exposed to the air stream for 30 minutes (250 m3 of air). During the sampling runs, air speed and altitude was monitored using an airborne telemetry system carried in the airplane. Data was transmitted to a lap top computer in real time.
A total of 11-30 min sampling flights on 5 different days in May were flown over corn stubble. Sampling times ranged from noon to dark and sampling altitude ranged between 75 and 150 ft. Viable F. graminearum spores were collected on 8 of the 11 sampling flights. Viable spores ranged from 1 to 5 spores per sample. A total of 16-30 min sampling flights on 3 different days in early June were flown over mixed hardwood forest, removed from corn stubble by approximately 1 mile. Sampling altitude ranged between 250 and 400 ft. Viable F. graminearum spores were collected on 8 of the 16 sampling flights. Viable spores ranged from 1 to 3 spores per sample. In mid-June, a total of 9 - 30 min flights were flown over a grass/hardwood forest hill top overlooking a agricultural valley with corn stubble on the valley floor. Sampling altitude ranged between 250 and 400 ft above the hill top and exceeded an altitude of 1000 ft above the valley floor. The hill top was located at a bend in the valley which directed the prevailing valley wind to impact on the hill side. The only corn stubble present in the area was located on the valley floor. Viable F. graminearum spores were collected on 2 of the 9 flights and the remoteness of the site suggested that the source of spores was the corn stubble on the valley floor, several miles distant and more than 1000 ft lower in altitude.
1998 In May-June 1998, the RPVs were outfitted with floats and the atmosphere 100-200 ft above Cayuga lake was sampled for the presence of ascospores. Viable ascospores were collected in each of these sampling flights (20). Flights over the lake supported the suggestion that spores from this fungus are transported in the planetary boundary layer, the source of spores was from a distant source and the presence of spores at the sampled altitude suggests that the spores can be transported long distances.
1999 During the winter months new spore samplers were developed which reduced the drag on the airplane particularly during the critical takeoff run. After highway testing and flight testing the samplers for durability, the new samplers were used for the 1999 aerial samples.
Winter wheat plots were inoculated with corn kernels colonized with F. graminearum conditioned to produce ascospores. A fungus strain was selected which was known not to occur in the area and could be identified using DNA techniques. During June while the fungus was sporulating, sampling flights were taken on 7 different days. We attempted to split the flights between the zones upwind of the plots (to capture background spores) and downwind of the plots to capture spores released from the plots. A total of 60 flights were taken but the flights were not equally split between upwind and downwind areas in relation to the plots. Generally, more spores were collected downwind from the plots compared to samples taken upwind. Laboratory conformation for the presence of the marked strain has not been completed to date.
Aerial samples collected during 1997, 1998 & 1999 suggests that ascospores of Fusarium graminearum. are transported considerable distances in the atmosphere. In addition, RPVs equipped with spore traps are a viable tool to sample the atmosphere between 50-1000 ft altitude.
This page was constructed by Gail Kampmeier at gkamp[at]uiuc.edu
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