VIEW ARTICLE

Effect of Pretreatment with Stimulator and Water Vapors on Subsequent Germination and Infectivity of Uredospores of Puccinia graminis var. tritici. R. C. French, Plant Physiologist, Department of the Army, Fort Detrick, Frederick, Maryland 21701; M. D. Gallimore, Agronomy Assistant, Department of the Army, Fort Detrick, Frederick, Maryland 21701. Phytopathology 62:116-119. Accepted for publication 5 August 1971. DOI: 10.1094/Phyto-62-116.

Exposure of dry spores to vapors of volatile stimulators in the absence of water vapor had no effect on subsequent germination. Pretreatment of spores in the presence of water vapor with high concentrations of vapors of polar stimulators (n-nonanal, n-nonanol) reduced subsequent germination and infectivity to zero and damaged spores. Hydration with low concentrations of nonanal and nonanol stimulated germination and infectivity above that of spores exposed to water vapor alone. Hydration in the presence of vapors of the nontoxic hydrocarbon stimulators, even at 10 µliters/4.0 ml water, resulted in subsequent stimulation of germination. Concentration of nonanol, which normally stimulates germination of spores on water, inhibited germination and damaged dry spores when applied in the presence of water vapor as a 2-hr pregermination (hydration) treatment. Exposure of inoculated wheat leaves to short pretreatments with high concentrations of polar stimulators in a moist atmosphere prevented or greatly reduced infection.