By Bill Robertson, Extension Cotton Agronomist
The National Agricultural Statistics Service (NASS) Crop Progress and Condition Report for Arkansas the week ending July 3, 2016 reported cotton flowering or setting bolls at 25% which was ahead of the five-year average of 16%. They also reported that 70% of the cotton was in good (45%) to excellent (25%) condition with only 10% being poor (5%) or very poor (5%).
Our April-planted cotton was flowering the last week of June when this NASS report was generated. Early May-planted cotton is starting to flower this week. The nodes above white flower (NAWF) value at first flower gives a good indication of the horsepower of the plant or its ability to supply the needs of a fruit load. In Arkansas we target of 9 to 10 NAWF at first flower and define cutout as NAWF=5.
We were seeing a lot of variability in NAWF in our April planted fields the last week of June. We saw fields ranging anywhere from 6 to 7 NAWF at first flower to fields that were still running in excess of 8 NAWF going into the second week of flower. The dominant factor for this range is related to available soil moisture. We saw a number of fields that were taking 5 to 6 days to put on a new node before irrigation was initiated. There are basically 25 days from squaring to first flower. The first indication of stress in squaring cotton can be seen in the rate at which new nodes are developed. Since new main stem nodes of cotton are added every 2.7 days (on average), NAWF value at first flower should be slightly over 9, i.e. 25 days of nodal development from square to flower divided by 2.7 days per node. Fields with NAWF values of 6 or 7 at first flower still have the potential to meet our yield goals. However, timing of inputs is very critical to meet plant demands to avoid an earlier than desired cutout.
This year we are seeing about as much horsepower going into flowering on our early-May planted cotton as I have seen in Arkansas. We generally see our most vigorous fields averaging 9 to 10 NAWF at first flower. I have counted numerous plants this week with 12 to 14 NAWF. The rapid production of nodes during most of squaring is the likely explanation for these fields and others that many County Extension Agents and consultants in the field have also seen. The lack of size difference in first position squares on plants has generated a lot of questions. We are not sure what this means down the road. While we have a great deal of horsepower, the potential demand could be great. A concern that most everyone has is the high retention of fruit. Most field we are monitoring have 95% or higher square retention. The combination of high demand and high retention can be disastrous if a significant stress were to present itself. More often than not in this situation, the plant sheds too much fruit for our liking.
It is important to know how much horsepower and the potential demand that exists in your fields to be able to satisfy plant demands to reach your yield goals. It is also important to consider retention values with regard to pesticide applications. The last thing we need to do is spend money on a product to keep fruit that we will shed down the road because the plant has no reserve to hang onto it when the going gets tough. Our goal at first flower is to have 80% fruit retention.