Missouri Cotton News
APRIL 1999

Have you checked your spray nozzles lately? A worn nozzle will have an increased output and may cause a poor spray pattern. Excessive output can be very expensive; especially, when herbicides are being applied due to chemical cost and crop damage by the herbicide. Possible chemical carryover due to the excessive rates can present problems the following year. A poor spray pattern can cause either excessive chemical being applied and get crop injury or not get proper weed control when the pattern is not covering all of the area with the proper herbicide rate. Are your tractors being operated at the speed at which the nozzles were calibrated? I have seen many instances where the tractor was operated at speeds in excess of the calibration speed. When this happens and the chemical does not work properly, one may incorrectly blame the chemical. Verify that the correct total amount of chemical was applied on the treated area.

Weed scientists have no business commenting on variety testing procedures. However, Dr. Bobby Phipps’ cotton variety trials continue to be criticized because in some cases Roundup Ready and BXN cotton varieties are not sprayed with Roundup or Buctril.

Some of this criticism is understandable: Farmers want research done in a way that matches the way they farm. It is good to know if the application of the special herbicide affects the crop yield.

However, some of this criticism bothers me- especially if it comes from industry folks. Putting the herbicide tolerant varieties together and spraying them is a great way to give the special varieties an unfair advantage. They won’t be tested against the best of the normal varieties- which might (or might not) out yield the special varieties.

The answer is to conduct a number of tests. In some tests, all varieties need to be placed together to see which ones yield highest. Other tests should be conducted to see if the herbicide has any affect on the cotton yield.

My message to farmers is to please relax. At the Delta Center, we test things many different ways and are getting the data that’s needed. In SOME tests all varieties are lumped together to test their true yield potential. In other experiments, varieties are tested with and without their special herbicide. We do some of the testing in the Weed Science Department and some testing is done in Bobby’s department.

We agree that most research should be done the same way that farmers farm. However, in some cases we need to break the rules to find out "what goes on inside." Is it really a problem that your tractor’s motor oil was extensively tested on an engine in a laboratory (as long as there was some on-farm testing)? Individual bits of research are easy to criticize. We look at all research before we attempt recommendations.

In the Weed Science Department we continue to test the special cottons with and without their herbicides. There has been no difference in cotton yield when the special herbicides were applied as labeled. We also look for preemergence herbicide damage- an advantage that is frequently cited for herbicide tolerant cotton. We see occasional, slight visual damage from the preemergence herbicides, but rarely see yield losses. Conversely, when we eliminate preemergence herbicides we routinely see reductions in weed control and crop yield. Your highest yield will result from growing a high-yielding variety and keeping it clean.

We always welcome farmer input and are glad you notice when experiments vary from farmer conditions. Never hesitate to give your suggestions. But remember that a good reason to criticize a ”transgenic + normal” variety test is to hide from varieties that can beat the ones you’re selling.

Have you asked yourself this question? Each year we hear of cases where the producer plants out of his normal sequence because some of the fields are too wet. Unfortunately, abnormal sequence may cause the farmer to spray a non herbicide tolerant field with a herbicide. The results can lead to a disaster. If some of the planted varieties are not herbicide resistant then good record keeping is critical. Be sure your field records are updated and correct. Good field records could prevent a nasty surprise. If you have to change fields when planting, be sure to flag where you stop. This flag would reduce the chances of misidentifying two different varieties such as a conventional variety and a resistant variety in the same field.

When planting herbicide resistant varieties, check the label on every bag of seed. This added step can insure that each bag is a herbicide resistant variety. In case there are problems with the seed, it is wise to have saved the tags off of the planting seed bags. By doing this, the lot number of the seed can be traced.

In 1997, we started a tillage project funded by Cotton Incorporated that evaluated deep tillage in a reduced till situation on a silt loam. The field had a hardpan from five to fourteen inches. The deep tilled plots were tilled fourteen inches deep using a paratill plow a few days before planting. We found a 134 pound increase in lint yield. In 1998, a decision was made to observe the effect of deep tillage under conventional, reduced and no-till methods of crop production. We observed a lint yield increase of 190 pounds on the conventional tilled plots that were deep plowed. The reduced till plots had an increased lint yield of 127 pounds. The deep tilled no-till plots produced an increased lint yield of 187 pounds more than the non-deep tilled plots. In the reduced till plots that had been deep plowed for two years there was only an increase of 57 pounds in lint yield. Both years the crop did not stress for water as severe as where the land had been deep plowed. We found that in a wet fall that is very important that the deep tillage shanks enter the furrows only on rows where the cotton picker wheels do not travel. If the picker wheels are on the chisel entry row, the picker will try to follow the chisel groove. This trial will be conducted for two more years.

Testing your soil may be a way to cut costs this year. With your normal fertilizer program you may have built up a surplus of some nutrients. You make a deposit with your annual fertility program just like you make a deposit in a checking account. With the crop prices so low and the financial stress that so many producers are facing, this may be a good time to make a withdrawal from that "soil bank account." The soil test will enable you to check the balance in your soil bank account. Of course if the account is in the red you may need to apply fertilizer. The soil test will help you prevent overdrawing the account.

With the cotton economy as it is this year all producers should be looking for ways to reduce input costs. Soil testing and appropriate fertilizer recommendations offer an opportunity to save money. Current University of Missouri soil test recommendations for P and K on cotton are based on three factors, 1) Target soil test level, 2) Crop removal, and 3) Build up. All fertilizer recommendations, university or commercial are calculated by combining these factors.

The target soil level is the amount of P or K at which adding more will not increase yield 9 out of 10 years. This is also known as the Critical Level. In terms of P this is 45 lbs. P/a. In terms of K this is 220+5 X CEC lbs. K/a. This works out to about 255 lbs. K/a for sand, 285 lbs. K/a for silt-loam, and 320 lbs. K/a for gumbo. Once again if your soil tests above these levels it is very unlikely that applying fertilizer will increase yields.

Crop removal is the amount of P or K that a crop of a stated yield will remove from the soil. A two bale cotton crop will remove 38 lbs P₂O₅/a and 35 lbs K₂O/a. Commercial recommendations often include a maintenance fertilizer application regardless of the soil test value. The University of Missouri does not recommend applying P or K when the soil test value is greater that target level + one years crop removal. This is a good place for you to save money. If your soil test for P is above 80 lbs/a no application is needed. If your soil tests for K is above 290 lb/a on sand , or 320 lbs/a on silt-loam, or 350 lbs/a on gumbo no application is needed. Give your self credit for building up your soil in years past. This year may be a good time to draw on your "soil P and K bank account".

This brings us to build up. Build up is how quickly do we want to increase the level P or K of a low testing soil to the target level. This number takes in to consideration a time factor in years and a crop removal factor. Recently the University of Missouri Soil Testing System made a change in our recommendation program to allow producers a choice in over how many years the build up will take. This gives producers the option of building up more quickly in good years or cutting back in lean times.

What does all of this mean? All fertilizer recommendations are based on the same factors. It’s how they are combined that leads to differences in application rates. All fertilizer recommendations are based on agronomics, some recommendations sell more fertilizer than others. Many commercial labs can give you University of Missouri soil test recommendations if asked. Get an independent unbiased opinion from someone with no axe to grind. Ask your fertilizer dealer for the numbers that your recommendations are based on. Bring you soil test numbers to the Delta Center Soil Testing Lab. We will be happy to compare recommendations for you.

1. Test fields for soil nutrients and add lime, phosphate, and potash and other nutrients as recommended.
2. Make sure ditches are adequate to quickly drain excess water off the field and break hardpans to improve internal drainage.
3. Select a high-yielding, well adapted variety that germinates well(the warm germination plus cold germination test results should total 130 minimum).
4. Plant only when the soil temperature 4 inches deep has warmed up to about 60? F by 8:00 a.m. and five days of warm and dry weather are predicted.
5. Plant on a raised bed.
6. Use a hopper-box fungicide like Prevail or System 3, or use in-furrow fungicides like Ridomil Gold PC, Terraclor, or Terraclor Super X when planting early, in poorly drained fields, and in gumbo.
7. If planting no-till, use a device on your planter to move trash away from the row so the sun will warm the soil around the seed faster.

Following these suggested procedures will give cotton farmers a better chance to produce high yields and profit. More information is available on the University of Missouri-Delta Center web page (aes.missouri.edu/delta).

At $0.70 per pound, the estimated value of cotton grown in Missouri in 1998 was $117.6 million. But are cotton growers getting all they can from their fields? Not according to a study conducted by a team of scientists at the University of Missouri-Delta Center led by Dr. Michael Boyd, Dr. Andy Kendig, and Dr. Allen Wrather. Their results indicated that weeds, insects, and diseases continued to reduce yield and grower income.

The estimated losses due to weeds, insects, and diseases in Missouri during 1998 were 20.2 million pounds of lint valued at $28.8 million.

These losses could be reduced if more growers used cotton pest survey reports (field scouting reports) for making pest control decisions.

According to a 1996 survey by the team, only 73% of the cotton growers in Missouri scouted or had their fields scouted for pests and used the information to determine which cotton pest control strategies to use. The team estimated that cotton yields were 50 pounds of lint per acre greater in fields where pest control decisions were based on pest surveys than in fields where pest control decisions were made without prior knowledge about the pests present in the fields. Because 73% of Missouri cotton growers used pest surveys when making pest control decisions, cotton yields in Missouri increased an estimated 14.1 million pounds of lint in 1996, 13.7 million pounds of lint in 1997, and 12.0 million pounds of lint in 1998. At $.70 per pound, the value of this yield increase was $9.8 million in 1996, $9.6 million in 1997, and $8.4 million in 1998.

An objective of the team is to get the remaining 27% of Missouri cotton growers to use pest surveys when selecting pest control tactics. Many effective pest control strategies are available to cotton growers, and wise decisions about which strategy to use should be based on pest survey information.

More information about cotton pest control practices may be found on the University of Missouri-Delta Center web page at aes.missouri.edu/delta.

Following these suggested procedures will give cotton farmers a better chance to produce higher yields and greater profits.

The seed companies tell me that the crop last year was poor and due to this some varieties are in short supply. Seed production was poor just like our lint production. Many of the transgenic varieties are especially scarce. If you have to replant it may be nearly impossible to get the seed of the better varieties. This means it will be more important than ever to get a stand with the first planting. With a poor growing season last year, planting seed quality may not be as good as usual. One could expect to get planting seed with less than normal vigor. It will be especially important to plant into warm soil.