Peanut pod wart, a relatively new disease to peanut culture, was first reported in Israel in 1988 attacking peanut plants and causing dark warts on the pod. The causal agents are variousStreptomyces spp. Scanning electron microscopy showed a significant difference between healthy and diseased tissues of the exocarp and mesocarp layers of the pod; there were no effects on the endocarp layer. The mesocarp cells of infected tissue were smaller and more compressed than those of healthy tissue. In most cases two cells under the peak of the wart were extremely large and the cells growing from them toward the surface were uneven, forming the shape of a fan. The pathogen could be isolated from the soil and rhizosphere, but in the pod it was found only in the waited tissue. The microorganisms isolated from the warts belong to different groups ofStreptomyces spp.; subsequent pathogenicity tests proved their virulence to a limited host range. In potato, these isolates ofStreptomyces spp. caused deep pitted scab; in peanuts they caused warts. Peanut seeds which developed in infected pods were free of the pathogen if the shell was undamaged. However, the pathogen is surface seedborne, and contaminated seeds during the mechanical cracking process.
Key WordsStreptomyces spp. seeds seedborne potato scab
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- 1.Bar, Z. (1992) Intensification of soilborne diseases of peanuts in the arid zone of Israel.Phytoparasitica 20:232 (abstr.).Google Scholar
- 2.Ben-Yephet, Y., Mhameed, S., Frank, Z.R. and Katan, J. (1991) Effect of the herbicide ethalfluralin on net blotch disease of peanut pods.Plant Dis. 75:1123–1126.Google Scholar
- 4.Easton, G.D. and Nagle, M.E. (1979) Efforts to control shallow and deep-pitted scab.18th Ann. Wash. State Potato Conf. Trade Fair (Moses Lake, WA, USA), pp. 61-74.Google Scholar
- 8.Kritzman, G. and Grinstein, A. (1991) Formalin application against soilborneStreptomyces.Phytoparasitica 19:248–249 (abstr.).Google Scholar
- 9.Kutzner, H.J. (1986) The family Streptomycetaceae.in: Starr, M.P. [Ed.] The Prokaryotes. Vol. 2, pp. 2028–2090. Springer-Verlag, New York.Google Scholar
- 12.Sanford, G.B. (1923) The relation of soil moisture to the development of common scab of potato.Phytopathology 13:231–236.Google Scholar
- 13.Walker, J.C. (1952) Diseases of Vegetable Crops. McGraw-Hill Book Co., Inc., London, UK.Google Scholar