North Carolina growers do not have sufficient information to make informed mepiquate chloride (MC) use decisions. Despite overall yield increases that approached 60 lb/A in 13 MC trials conducted during 1988 and 1989, location effects predominate the observed variation in response to MC.

This study was conducted to determine if field measurements of crop growth at early bloom could be used to reduce this variation and predict cotton response to MC. Five crop growth indices: plant height, number of nodes, internode length, sympodia, and bloom period were determined at early bloom. Correlations of these indices with node of last boll and lint yield indicated that all indices were poorly correlated with node of last boll. Lint yield was correlated with early bloom internode length (r=.53) and length of bloom period (r=.80). The data suggests that grower measurements of these indices may improve their MC use decisions at early bloom.