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Vibrational Releases of Conidia by Drechslera maydis and D. turcica Related to Humidity and Red-Infrared Radiation. C. M. Leach, Professor, Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331; Phytopathology 70:196-200. Accepted for publication 5 September 1979. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-196.

Massive discharge of conidia was triggered by lightly vibrating sporulating leaf lesions infected with Drechslera maydis and D. turcica. Visual observation of vibrationally liberated conidia with special illumination revealed that the spores were violently discharged into the air perpendicular to the lesion surface. Vibrational release was markedly influenced by relative humidity (RH) and the presence or absence of red-infrared radiation (IR). These factors also were important in spontaneous spore liberation in the absence of vibrations. Vibrational release of conidia was most abundant from specimens exposed to IR at low RH and least from specimens held in darkness at RH 100%. There was a small, but significant, discharge when specimens were vibrated while exposed to IR during saturation. Vibrational release in darkness at lowered humidities ranged from neglible to moderate and was generally insignificant compared to liberation from irradiated specimens. Exposure to IR increased vibrational release during the following dark period.