The effects of Meloidogyne incognita infection on the growth, development, and water relations of cotton plants were studied in microplots. Microplots containing fumigated (methyl bromide) soil were infested with M. incognita eggs collected from greenhouse grown tomato plants at the rate of 5,000/pint of microplot soil. An additional treatment consisted of nematode infestation as described plus application of aldicarb (Temik 15G) broadcast over the plot surface at the rate of 1.5 lb active ingredient/acre at planting. Control plots that received no nematodes were also included for comparison with the other two treatments. Plant growth and development were monitored through plant growth mapping (COTMAP), and various physiological parameters including transpiration, diffusive resistance, leaf water potential, and water flow through intact plants were also measured. Nematode infection decreased plant height and the number of main stem nodes at 29 and 36 days after planting. Infection also decreased plant height at harvest, total bolls produced by plants, the number of sympodial branches produced, and seedcotton yield. In addition, nematodes appeared to increase the node number of the first sympodial branch (FN) and decreased the position of the uppermost sympodial branch with two boll positions (H2). Infection by M. incognita increased cotton leaf temperature and diffusive resistance and decreased transpiration, leaf osmotic potential, and water flow through plants. Application of aldicarb minimized most of the nematode effects seen.