VIEW ARTICLE

Effect of Meloidogyne incognita acrita on the Susceptibility of Cotton Plants to Verticillium albo-atrum. Farid Y. Khoury, Plant Pathologist, Ministry of Agriculture, Aleppo, Syria; Stanley M. Alcorn, Professor, Department of Plant Pathology, University of Arizona, Tucson 85721. Phytopathology 63:485-490. Accepted for publication 1 October 1972. DOI: 10.1094/Phyto-63-485.

Addition of 1,000-2,000 Meloidogyne incognita acrita larvae/pot at pre-emergence, first-leaf, or third-leaf stages of development of Gossypium hirsutum ‘Deltapine Smooth Leaf’ (DSL) and G. barbadense ‘Pima S-2’ (PS-2), followed 3 days later by 30-120 ml/pot of a suspension of Verticillium albo-atrum, significantly increased the number of plants infected by this fungus. The addition of 2,000 larvae/pot at pre-emergence, first-leaf, or third-leaf stages, followed 3, 7, 15, or 27 days later by 60 ml/pot of a suspension of V. albo-atrum, increased the susceptibility of all plants to V. albo-atrum except for those of DSL inoculated 27 days after the third-leaf stage. Symptoms were more severe on plants inoculated with the fungus and high concentrations of the nematode than on plants inoculated only with the fungus. The susceptibility to V. albo-atrum of nematode-treated PS-2 plants equaled or exceeded the susceptibility of DSL plants of comparable ages. The number of galls induced on cotton roots by the nematode was not influenced by V. albo-atrum. Potassium hydroxide-soluble carbohydrates (CHO) in roots of both cultivars and susceptibility of the plants to V. albo-atrum increased as the seedlings aged through approximately the first- to third-leaf stages. M. incognita acrita had no significant effect on CHO levels in the roots of either cotton cultivar.