ENVIRONMENT AND WHITE PINE BLISTER RUST INFECTION 493 



distance. With increasing distance the rust infection follows an 

 exponential curve. In British Columbia, according to the published papers 

 by Kimmey and Buchanan, and some in Kittery Point, Maine, this distance 

 is about 25 feet. In northern Minnesota, in upper Michigan, and in 

 northern Wisconsin, this distance is 300 feet. Now, according to prior 

 work, this has to say that something in the environment is allowing these 

 spores to go much, much farther, or a much greater proportion of them are 

 living to cause infections. I wonder if maybe this isn't the case in 

 areas where it's so cold and so wet and so cloudy so much of the time 

 that a spore can live more than a single night in these areas and maybe 

 this is why the hazard is so much higher. I said in one of my papers that 

 maybe it's a jump to this zone instead of a climatic gradient. I think 

 this might be where the sporidia might live one day, or more than one 

 day. 



