412 



BOTANICAL GAZETTE 



[may 



plant is readily susceptible to infection, as is also the uninjured plant if kept 

 in humid condition, but that the uninjured plant in a relatively dry atmos- 

 phere is difficult or impossible to infect. In case of successful inoculation, 

 the diseased spots were well developed at the end of a week. The removal 



Fig. 3. Mycelium showing branching and septation.— Fig. 4- Showing m> ^ u]ate 

 below stoma and hyphae emerging through the stoma.— Fig. 5. Showing ca ^ 



spores as borne upon hyphae.— Fig. 6. Spores showing shape, septation an ca^ 

 lation.— Fig. 7. A young cluster of hyphae.— Fig. 8. An older cluster of hyp * - 



of the protecting bell jar from plants already infected resulted usu ^^ 

 cessation of development of the spot. These facts agree wel1 ^^^ 

 field observation that the most damaging infection occurs at the ]^^ fo [ 

 points well adapted to collect and hold water, thus pro 

 optimum development of the fungus. 



rfding conditions for 



