Monitor Nodes Above White Flower
The primary use of the nodes above the white flower (NAWF) measurement in pest management decisions is determining
when to stop sampling for lygus. You can stop monitoring for lygus 10 days after cutout: when Acala cotton has 5 NAWF
cotton has 3.5 NAWF. At this stage, the crop has set more than 95% of its final yield.
Time the counting date by ascertaining when a majority of the plants in the field have a white flower at FP1 on the
first fruiting branch.
- Select a minimum of 5 plants with an FP1 flower from each of 4 different areas in the field.
- Count the node with an FP1 flower as zero and move toward the terminal.
- Record the total nodes above white flower for all of the samples.
- Record the number of plants sampled.
- Divide the total number of nodes by the total number of plants sampled.
If the terminal node has a leaf associated with it of at least 1 inch in diameter, consider it a new node.
You can use NAWF information to ascertain if cotton plant growth has been stressed.
- Acala varieties that have not
experienced stress before bloom should have 8 to 9 NAWF at early bloom; Pima should have 9 to 10. A value of
8 or below is clear
evidence that early season development rates have been limited by stresses due to irrigation, soil compaction,
salinity, disease, or nematodes. All of these factors affect the roots and, in turn, limit the plant’s
rate of growth.
- Three weeks after first bloom, there should be 6 to 7 NAWF for Acala and 6 to 8 for Pima for
and reproductive growth. NAWF should decrease by about one every 8 days for Acala and one every 10 days