RUST RESISTANCE OF OAT VARIETIES. 



About 15 seeds per pot were sown for the seedling work, and the 

 plants were thinned later, so that on an average about 8 plants 

 per pot were inoculated. Plantings were made every few days 

 from November, 1915, to April, 1916. Thus, there was always a 

 series of plants coming on ; as soon as one series had been inoculated 

 another was about ready. 



The cultures were kept in a cool greenhouse (night temperature, 

 50° to 55° F. ; day temperature, 60° to 65° F.) and watered not less 

 often than every alternate day. The inoculations on the seedling 



Fig. 1. — Glass-topped galvanized-iron moist chamber used for seedling plants. 



plants were always made when the first (seedling) leaf was still 

 vigorous and of a normal green color; that is, when the plants were 

 only 3 to 5 inches high. This first leaf was always the only one 

 inoculated. All others, with the " shoot," were kept trimmed off. 



Spore material of both the oat rusts was obtained from the Min- 

 nesota Agricultural Experiment Station and increased for use as 

 needed on stock cultures of the White Tartarian oat, the variety 

 used as a check. 



About ten varieties usually constituted the series treated on any 

 one day, one set being inoculated with stem rust and the other with 

 crown rust. No plants were left uninoculated, but one pot of White 

 Tartarian serving as a check on the other varieties was always sown 

 and inoculated with each series. 



The inoculations were made by removing urediniospores with a 

 flattened needle from a leaf bearing a heavy infection and placing 



