Cotton Squaring June 15?

— Written By Curtis Fountain and last updated by
To:  Duplin Co. Cotton Interests 

From:  Curtis D. Fountain

            Agricultural Extension Agent – Field Crops

If your cotton was squaring June 15, it is time for the 1st plant growth evaluation. This statement assumes the use of the Modified Early Bloom Strategy (2013 NCSU Cotton Information pages 55-56).

For the Modified Early Bloom Strategy, cotton should be first assessed 10-14 days after 1st square. Plant height, height-to-node ratio, and internode length are factors considered.

Assume 3 days for each node of growth in utilizing the tables. If a cotton plant has its 1st square on node 5 and has 9 total nodes, the plant has been squaring for approximately 12 days (total nodes (9) – node of 1st square (5) = squaring nodes (4) X days/node (3) = 12 days after 1st square).

Height-to-node ratio is calculated by measuring the plant helght (in inches) and counting the number of nodes. For example if a plant is 18 inches tall and has 9 nodes, the height-to-node ratio is 2.0. With the cotyledons (seed leaves) counting as node 0, each alternating mainstem leaf is counted as a node. The uppermost unfurled mainstem leaf that is 1 inch or larger in size represents the uppermost node.

The internode length is the plant mainstem distance (in inches) between 2 nodes. For table purposes, the internode length between 3rd and 4th mainstem leaves (from the top of the plant) and the internode length between 4th and 5th mainstem leaves (from the top of the plant) should be measured with the greater length utilized.

Remember tables note broadcast rates of 0.35 lb/gal active ingredient formulations of mepiquat chloride. Tables were developed on an “either or” basis. For example using the 10-14 days after 1st square table, if the height-to-node ratio is > (greater than) 1.85 inches or if the internode length is > (greater than) 2.5 inches, the corresponding application rate is recommended. If the height-to-node ratio is > 1.85 inches and the internode length is > 2.5 inches, corresponding application rates are not additive.

Appropriate (typically lower rate) applications now and at early bloom provide “more bang for the buck” than later post-bloom (typically higher rate) applications.


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