Fruit rot of sweet pepper caused by Stemphylium lycopersici in Japan
A severe rot of postharvest fruits of sweet pepper, a variety of Capsicum annuum, was found in Kagawa Prefecture in southwestern Japan in August 1999. A fungus, isolated repeatedly from the diseased fruits and identified as Stemphylium lycopersici, was demonstrated to be pathogenic to fruits of sweet pepper. The disease was new to Japan, and the fungus was added to the pathogens causing fruit rot of C. annuum.
Pathogenicity of Stemphylium lycopersici isolated from rotted tobacco seeds on seedlings and leaves
A preemergence damping-off of tobacco (Nicotiana tabacum L.) was found in Fukuoka, Japan, in 2009. A fungus repeatedly isolated from the black-rotted seeds reproduced the symptoms in tobacco seeds, and the preemergence damping-off developed after flower and soil inoculation with the fungus. Brown spots and blight developed on leaves of tobacco seedlings after inoculation with the isolate. The fungus was reisolated from the rotted seeds and blighted leaves. The causal fungus was identified as Stemphylium lycopersici based on morphology and phylogenetic analysis. This is the first report to confirm the pathogenicity of S. lycopersici in tobacco in the world.
THE QUANTITATIVE AND QUALITATIVE RELATIONSHIP OF ULTRAVIOLET AND VISIBLE RADIATION TO THE INDUCTION OF REPRODUCTION IN ASCOCHYTA PISI
Irradiation under either daylight fluorescent lamps or diffuse sunlight stimulated pycnidial development in 40 isolates of Ascochyta pisi. Sporulation varied among these same isolates when grown in darkness, and ranged from none to profuse. Irradiation of selected isolates through filters showed the importance of ultraviolet radiation in stimulating reproduction. The precise relationship of quality, intensity, and length of exposure of radiation to induction of sporulation was studied with monochromatic radiation at 21 °C. Treatment of colonies with monochromatic radiation of wavelengths 2378 A to 5461 A (band width 132 A) at the same intensity of 100 μw/cm2 and with exposures ranging from 1/50 to 20,000 seconds proved conclusively that only ultraviolet radiation induced sporulation. Two wavelengths, 2378 A and 3131 A, were notably effective in inducing pycnidial formation over a wide range of exposures. The dosage effective in inducing sporulation decreased with decrease in wavelength. Similarly, the min...