Control of Early Blight of Greenhouse Tomato, Caused by Alternaria solani, by Inhibiting Sporulation with Ultraviolet-Absorbing Vinyl Film. Demetrios John Vakalounakis, Plant Protection Institute, Heraklio, Crete, Greece. Plant Dis. 75:795-797. Accepted for publication 12 December 1990. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-0795.

Fifty-two of 59 isolates of Alternaria solani from tomato (Lycopersicon esculentum) were light-dependent for sporulation in pure culture (effective wavelengths shorter than 360 nm), whereas seven isolates (approximately 12%) were light-independent. Tomato cv. Earlypak No. 7 was grown without fungicides during the 1984–1985 and 1985–1986 crop seasons in an experimental greenhouse covered with an ultraviolet-absorbing (UVA)-vinyl film (lower limit of transmission at 385 nm) and in a control greenhouse covered with a common agricultural (CA)-vinyl film (lower limit of transmission at 290 nm). At the end of the growing season, disease incidence in the UVA-vinyl greenhouse was reduced to less than 50% of that in the CA-vinyl greenhouse. At the same time, plant growth in the UVA-vinyl greenhouse was better than in the CA-vinyl greenhouse, when plant height, number of inflorescences, and yield were compared.