Monitoring Midseason Cotton Growth

This section brings together all the various plant monitoring measurements and observations that provide clues as to the correct input management. Weighing any or all of them helps when determining whether or not to alter management inputs. There are several measurements utilized to make sure growth and development are occurring normally and a combination of these measurements is suggested. During bloom, growers and consultants should continue to record height and mainstem nodes, nodes above white flower (NAWF) counts, square retention and maximum internode distance on a weekly basis.

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Plant Height

13;10;Height of the mainstem is one of the most common cotton measurements and it can be useful in making management decisions when combined with other information. Generally at first bloom or shortly thereafter, cotton is growing at its maximum rate. A growth rate of about 1 inch per day is the upper limit of acceptable growth. Growth more rapid than this indicates an alteration in management is needed and using mepiquat chloride may be beneficial.

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Mainstem Nodes

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13;10;13;10;Development of mainstem nodes is also close to its maximum rate near first bloom. There should be a new mainstem node about once every 2.5 to 3 days — or approximately one every 40 to 50 DD60s. Water availability and carbohydrate production are the main influencers of mainstem node development. More important than the number of mainstem nodes on a given day is whether or not the number of days or DD60s between new nodes is increasing. If this is not occurring, or vegetative growth is not slowing, by the third or fourth week after bloom, an investigation is warranted.

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Squaring Nodes or Nodes Above White Flower

13;10;The maximum number of fruiting branches prior to bloom, or the maximum NAWF, is an excellent indication of vigor. NAWF is effective because it directly corresponds to energy absorption by the reproductive and vegetative demands of the plant. This measurement monitors the difference between the rate squares reach bloom and the rate new vegetation and nodes are produced.13;10;As NAWF declines, nodes are being produced slower than first fruiting position squares reach bloom. This value ranges from 5 to 10 with 8 and 10 nodes being most common when stress has not been a significant factor. Values of 7 or less at first bloom indicate low vigor and using a PGR is not recommended until the stress is alleviates as noted by NAWF values increasing to normal range. If the value is closer to 10 and/or does not decline at a rate of about 1 node per week, vigor is high and using a PGR may be beneficial. NAWF of 5 indicates the plant is entering cut-out.

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Maximum Internode Distance (MID)

13;10;As mentioned previously, the maximum internode distance (MID - the distance between the 4th and 5th nodes from the terminal) is the most sensitive, available measure of current vigor. It encompasses all effects current inputs are having on growth. It also reflects the current relationship between carbohydrate supply and demand. After first bloom, if this distance exceeds approximately 3 inches, current growth is vigorous and needs control. If it is less than 2 inches, growth is limited and may need investigation. In some situations, cotton having a MID under 2 inches may be a perfectly normal response to retention, PGRs, and environment.

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Average Number of Squaring Nodes by Days After Planting

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This article is from the Cotton Management Guide, a publication with year-round advice on managing high-yielding cotton. Download the Deltapine Cotton Management Guide now or sign up for new content to be delivered to your email each month.

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