Aerial Dispersal Risk of Late Blight,

Phytophthora infestans

D. E. Aylor, W. E. Fry, & E. J. Shields
Dept. of Plant Pathology & Ecology, Connecticut Agricultural Experiment Station, New Haven, CT
Department of Entomology, Cornell University, Ithaca, NY

Before testing a system in the field, it is generally wise to work out as many parameters as possible in the laboratory. Here, Don Aylor, of the Connecticut Agricultural Experiment Station, is releasing spores into the wind tunnel. He is visiting Elson Shields at Cornell University to test in a wind tunnel the parameters of trapping late blight spores via the remote controlled airplane trapping system (RPV) developed by Shields. The two will be collaborating on a grant proposal that uses Shields sampling system to assess the risk of late blight infection in potatoes.

	Operator testing the spore collecting system in a wind tunnel at Cornell University.
	Closeup of the testing of two sizes of petri dishes on the airplane wing to see which is the more efficent collector (hint: it's the smaller one, trapping 40% more particles per unit area than the larger dish).

Four preliminary sampling flights on two different days separated by 1 week were flown over late blight infested potatoes during September 1998 to investigate to feasibility of using RPV's equipped with spore traps to study the long ranged movement of late blight sporangia from infested fields to uninfested fields. The trapping surface consisted of a standard plastic petri plate completely filled with 1% water agar. Petri plates were mounted vertically in the sampler and perpendicular to the air stream through the sampler. Samplers were open and closed remotely after takeoff and before landing. Sampling altitude ranged between 150-200 ft during the sampling period.

During the first 2 sampling flights, only 1 sporangia was trapped in each sampler (4 total). One week later, more that 200 sporangia were trapped in each sampler during each of the two flights. Differences in trap catches between the 2 different sampling days was explained by the maturity of the fungus in the potato field and the time of day sampled. Flights during the first sampling day was targeted during the time of sporangia release and flights during the second sampling day were targeted 1-2 hrs after peak sporangia release. Weather conditions were very similar each of the sampling days with mostly sunny skies and air temperatures ranging between 75-80 degrees F.

This preliminary aerial sampling data was used in a grant proposal submitted to the NE IPM program titled "Phytophthora infestans Aerial Dispersal Risk to Potato Late Blight IPM". The grant was funded for 3 years. Intensive aerial sampling will be conducted during years 2 & 3 of the grant (2000 & 2001).

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