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New Diseases and Epidemics A New Green-Sterile Disease of Guar in South Africa. H. Ben-Moshe, Department of Microbiology, University of the Witwatersrand, Johannesburg, P.O. Wits, 2050, South Africa. M. E. C. Rey, M. Sibara, H. M. Garnett, and B. Beck. Department of Microbiology, University of the Witwatersrand, Johannesburg, P.O. Wits, 2050, South Africa, and P.O. Box 727, White River, 1240, South Africa. Plant Dis. 75:638-643. Accepted for publication 24 December 1990. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-0638.

Guar (Cyamopsis tetragonoloba) in South Africa showed symptoms of small necrotic lesions on the leaves and reduced inflorescences. About half the seeds from infected pods were distorted and did not germinate. These symptoms are unlike any other viral diseases reported in guar, and the disease has been named the green-sterile disease. A flexuous viral particle (750 15 nm) has consistently been isolated from infected plants and seed. This viral particle is transmissible to Glycine max, Lycopersicon esculentum, Phaseolus vulgaris, Vicia faba, and Vigna unguiculata by mechanical inoculation. Symptoms on indicator plants were mainly localized or systemic red veins and chlorosis, whereas guar showed necrotic lesions after secondary mechanical inoculation. Nonpersistent aphid transmission was successful in some cases. Serological tests indicated a strong relationship to the potyviruses, namely, bean common mosaic virus, bean yellow mosaic virus, soybean mosaic virus, and potato virus Y. Cross-reactivity with guar symptomless virus antiserum was also established.