PLATE 27 

 Relation of soil temperature to onion smut infection. 



This shows the results from a series of experiments in which the methods described 

 for Plate 26 were repeated with the soil temperatures restricted to the critical limits 

 between 25° and 29° C. and controlled more exactly. Note the marked reduction in 

 infection at 27.5° and complete inhibition at 29°, thus establishing, but with more 

 exactness, the conclusions illustrated in Plate 26. 



For the percentage of infected seedlings at these temperatures and other details, see 

 Table VIII and the accompanying text. 



