Level of inoculum suitable for studies on the relationship of coffee seedlings and Rhizoctonia solani or Myrothecium roridum

Suitable levels of inoculum of Rhizoctonia solani and Myrothecium roridum f or the induction of symptoms in coffee (Coffea arabica L.) seedlings were d etermined in greenhouse tests based on the percentage of seedling mortality and disease incidence. Best inoculum level for R. solani and M. roridum wa s 15 and 10%, respectively. Myrothecium roridum was more virulent than R. s olani, and thus caused higher mortality of coffee seedlings. For both patho gens, as the inoculum concentration increased, the dry weight of plants dec reased. A direct positive relation between incidence of the disease and con centration of the inoculum was detected. It was found that R. solani is mor e persistent than M. roridum in the inoculated soil.