VIEW ARTICLE

Association of Early-Season Vesicular-Arbuscular Mycorrhizae with Increased Growth and Development of Cotton. J. R. Rich, Former Graduate Research Assistant, Department of Plant Pathology and Plant Genetics, University of Georgia, Athens 30602, Present address: Graduate Research Assistant, Department of Nematology, University of California, Riverside 92052; G. W. Bird, Associate Professor, Department of Plant Pathology and Plant Genetics, University of Georgia, Athens 30602, Present address: Associate Professor, Department of Entomology, Michigan State University, East Lansing 48824. Phytopathology 64:1421-1425. Accepted for publication 3 June 1974. DOI: 10.1094/Phyto-64-1421.

Vesicular-arbuscular (VA) mycorrhizae are ubiquitously associated with cotton (Gossypium hirsutum L.) in Georgia. Increased early-season root and shoot growth in the presence of Endogone calospora, together with earlier flowering and boll maturation, suggests a beneficial relationship between this fungus and cotton. In field observations, VA mycorrhizae were present five days after seedling emergence and confined mainly to the radicle. Arbuscules were the predominant sign of infection. Seven days later, arbuscules and vesicles were equally predominant, and present only in the cortex of feeder roots. The logarithmic phase of growth for VA mycorrhizal infection of cotton was from 5 to 25 days after seedling emergence. Under field conditions, there was a significant positive correlation between early-season mycorrhizae and vegetative growth and development of cotton. The data are discussed in relation to control of plant parasitic nematodes and a possible joint role of VA mycorrhizae and nematodes in the cotton stunt disease complex.