These averages represent the growth and development for the field and provide the basis for calculating plant vigor, first fruiting node, and square retention. Plant Vigor Plant vigor indicates the early growth potential of cotton plants. It compares plant height to the total number of nodes to determine how tall the plants are for their age. Nodes represent a good measurement for age, as they are relatively unaffected by stress, while plant height is quite sensitive to stress. Cotton plants with low vigor will be shorter than those with optimum vigor at a specific mode number.
Excess vigor is denoted if a plant is taller than the optimum at the specific node number.
When plant vigor is low, determine the cause. Factors that can cause low vigor are stresses from moisture, temperature, seedling disease, etc. If the index indicates high or excess vigor, examine fruit retention closely. Many times excessive plant height is a result of early fruit shed, which often is caused by insect pressure. Practices to consider when vigor is excessive include insect control and PIX applications.