|July 1, 2007
The only county that contacted me about using the thrasher was Concho County. Callahan, McCulloch, Runnels, and Taylor Counties harvested their plots with a combine. If you are wanting to process grain please contact me and set up a date. As the summaries from these tests are completed, I would appreciate receiving a copy. These summaries are sent to the companies that market the seed so they can determine which varieties preform best in each region. The companies that receive summaries early tend to support our programs favorably each year.
Many areas of the district received over 5 inches of rain this month. For the most part the temperatures have been great for man and beast which are not the best conditions for growing cotton. Most of the cotton will be reaching the 1/3 grown square stage in the next two weeks. Any soil applied fertilizer applications need to be made before the 1/3 grown square stage, if it is not, producers will need to foliar apply nutrients; which is more expensive. Because of the adequate soil moisture conditions when we started this crop, the cotton plants are very healthy and the upper foot of soil contains a large percentage of the existing root system. If July and August is hot and dry these plants will suffer. There will be a combination of things that will contribute to this stress. Factors include: 1) these plants have a lot of leaf surface area and will transpire a lot of water through the natural openings in the leaves, 2) the root system has not explored and developed extensively to depths of four to five feet, 3) even though adequate soil moisture and nutrients exist, once the plant begins blooming and setting fruit the root system's expansion and exploration is reduced due to the plants normal processes of boll development. So the best opportunity to develop a more extensive root system is before blooming begins. Producers can encourage root development by making sure that adequate nutrients are available.
Prior to 1/3 grown square, all side-dress nitrogen applications need to be made. The root system will need time to recover before reaching the stressful moisture and nutrient uptake period. Soil applied fertilizer applications made at first bloom or later usually results in yield reductions. If the window of opportunity was missed to make soil applied side-dress applications of nutrients, then foliar application is the alternative. After the crop begins to bloom a producer can foliar apply up to six pounds of actual nitrogen per week after the crop begins to bloom. If soil nitrogen content is low then foliar applications of nitrogen should be made on a weekly basis if yield potential is high.
Research at the University of Arkansas has shown that under good conditions 30% of the foliar-applied urea can be absorbed during the first hour after application. Within 6 hours the nitrogen could be detected in the bolls and within 24 hours most of the labeled N that the leaf had taken up moved into the bolls. Based on tagged 15N(stable isotope) studies, the efficiency of foliar urea is high, with 50 to 70% of the applied tagged N recovered inside the plant. This compares to typical recoveries for soil applied tagged N of 50%.
Two of the 21 tests planned for this year have been lost due to weather conditions. If you loose a plot please let me know; seed company representatives often want to visit the tests during the summer.
Linked is the recent a copy of the Cotton Physiology Today publication on "Root Physiology and Management". Information contained in this publication will be a useful reference. You will get a better understanding of the shape and structure of the roots and how to manage the plant for growth.
Due to favorable conditions resulting from several days of rain in June, seedling disease was a major problem in some acreage. As the season progresses and rapid plant growth occurs the extent of the problem will become more visible. We may have some acreage with plant populations as low as one plant every 18 inches. The yield potential is already impacted and a long boll set period will be needed to produce 200 to 300 pounds of lint. It is to late to replant and management choices will impact yield and harvest.
Compacting the season for late planted cotton is a producers opportunity to put their knowledge to the test. You can't speed up boll development, it takes heat units to get it done. If we could keep cotton in the ideal temperature range it would max out at 90 degrees during the day and stay above 70 at night. In July and August in our region the daytime temperatures tend to cost us some valuable boll development time. What can be controlled is the plant structure, fruit development and boll set. If we have a healthy plant with plenty of soil moisture and nutrients then a plant growth regulator may be needed. If you have a variety with a lot of growth potential, you may want to apply 4 ounces of mepiquat chloride when 50 percent of the plants have a square about the size of a match head. The larger the plant the higher the rate of mepiquat chloride that will be needed. Never apply a plant growth regulator to a cotton plant that is stressing for water. By controlling the plant development you can reduce the plants height and allow for more sunlight penetration deep into the canopy. By reducing the amount of shadowing, leaf production needed for plant growth is increased. Don't let the insects take much of the early fruit set because the number of weeks to load the plant is very short. Basically the boll set period ends on September 1 for quality lint so that is the target date to get the plant loaded with bolls. To meet this September 1 goal for a bloom, the square has to be on the plant by July 7. For the picker type cotton varieties planted June 21 the square set won't begin until around July 25 and it won't bloom until approximately August 20. That means you have a two week boll set period for quality cotton. Since the plant structure has been modified to keep it short we might be able to squeeze three weeks of boll set and then we have to call it good enough and finish the crop. The bottom line is we have to set all the squares possible for the first three weeks and retain them as bolls to be harvested at the end of the season. There isn't time to make a mistake.
Late planted grains still have a window of opportunity but it is shutting fast. The linked information was compiled by Calvin Trostel the Agronomist at Lubbock. It provides a lot of the information that you need to consider.
Is it to late to plant grain sorghum? It just depends on how big a gambler you are. If you plant a 100 day grain sorghum on July 1 you may or may not have enough time. It will depend on the temperatures at the end of the season and when it freezes. If you do plant grain sorghum late, the application of nutrients should be made prior to the seven- to ten-leaf stage (depending on maturity group).
I have had several producers and Extension Agents indicate that glyphosate has not been working well in controlling weeds this season. That is probably due to the environmental conditions that existed at the time the chemicals were applied. Getting as much herbicide into the plant as possible is important. If the herbicide being applied allows for a crop oil concentrate to be used, that would be a better choice than a surfactant due to the improved penetration through the cuticle. Early morning applications of herbicides are important because wind speeds are lower and relative humidity is higher. Try to complete herbicide applications before the temperature gets above 80 degrees F and the relative humidity drops below 30 percent. Due to the hard water in our region it is important to use ammonium sulphate in the tankmix; the range is between .08 to .17 pound of ammonia sulphate per gallon of water. The smaller the weed the better the control is a correct statement when it comes to controlling annual weeds. For control of perennial weeds the bloom stage is the target time period for maximum weed control. Generally, applying a herbicide to weeds that are moisture stressed, dusty, or mature will result in a poor level of control and should be avoided. This combination of steps should improve the level of weed control achieved by producers. Coverage is another critical consideration that makes the choice of nozzles and the amount of water applied very important. With the proper amount of water and adequate pressure it is hard to beat the herbicide coverage provided by an ordinary flat fan nozzle, the problem is off target drift and if it is a concern then a different nozzle should be selected.
On July 9, there will be a training conducted at Abilene for producers needing to obtain a Private Applicators License. For more details and to register for the meeting call Gary Bomar at (325) 672-6048.