COTTON CROP DISAPPOINTING

Cotton lint on soil following crop destruction from drought stressed crop in 2012.
 

The drought of 2011 and 2012 has certainly had a major negative impact on cotton in the local area this year.   Yields this year were such that many producers are having their crop adjusted out by Crop Insurance as the economics of the situation indicated that it was more economical to collect insurance on the adjusted crop yield and destroy the remaining crop, rather than harvest the poor crop.

            As the cotton harvest nears completion, it is important not to forget about destroying those cotton stalks as soon as the crop has been removed or terminated to aid in reducing costs for the Boll Weevil Eradication Program (BWEP).  This year there has not been one boll weevil caught in Nueces County, although there have been some caught just to the south recently.  Good progress has been made on this front, so let’s keep it that way.

            The cotton stalk destruction deadline for Nueces County remains September 1, 2012.

In its native habitat cotton is a perennial shrub that may survive for many years. The perennial habit of cotton allows it to regrow following harvest, and provides the potential for development of hostable fruit (squares and bolls) for boll weevil feeding and reproduction. Under good environmental conditions, cotton plants can generate hostable fruit in three to four weeks.  Additionally, the destruction of the cotton stalks will also preserve soil moisture for the following season.

    When field conditions and weather are favorable for tillage, stalks can be shredded and then disked to destroy the intact plant. Stubble stalk pullers can also be used to uproot the stalk. These mechanical methods are generally successful, but some stalks may survive these operations. Also, many growers are implementing reduced tillage systems which do not allow for primary tillage operations, causing producers to evaluate new methods for stalk destruction.

    There has been much interest in alternative cotton stalk destruction throughout the South Texas area in recent years. While many producers still use various tillage methods to destroy their cotton stubble, be aware that there are other choices available. Regardless of the method chosen, the primary purpose of destroying cotton stalks remains the same and that is to prevent  cotton fruiting sites (squares or bolls) that are a food source for the boll weevil.  These fruiting sites will allow the boll weevil to reproduce and increases its winter survival rate.

    Several herbicides have been registered for cotton stalk destruction. Herbicides available include, but are not limited to 2,4-D (ester and amine formulations) and several dicamba products (Weedmaster, Clarity, Banvel). For these products to be legal for cotton stalk destruction, the label must contain a section addressing “crop stubble” or specify cotton as the target pest following harvest.

    Based on most recent field research, it appears the low-volatile, amine salt formulations are equally as effective as the ester formulations for cotton stalk destruction, and minimize problems associated with off-target drift. The first application should be at the rate of one pound of active ingredient/acre (eg. 1 qt. of a 4 lbs. a.i./gal. formulation). Generally, a second application of 0.5 to 1.0 lb. a.i./acre will be necessary for control of any live stalks and emerged cotton seedlings.

    To obtain optimum results, cotton stalks should be shredded (6 to 8 inch height) and the spray application should be made soon after shredding. Best results are achieved if the herbicide is applied the same day as the shredding operation. To achieve optimum effectiveness, some growers have mounted spray booms directly on their flail shredders and are banding their herbicide during the shredding operation, and achieving excellent results. Note that thorough coverage is essential, and should be in the range of 5 to 10 gallons water/acre. Also, the addition of surfactant at the rate of 0.5% v/v (2 qts./100 gals. water) is recommended.   Research has should that there is essentially no difference in killing regrowing cotton plants with 2,4-D between treating shredded stalks within one day, treating 2 weeks after shredding, or standing stalks.  However, other products are less effective on standing stalks.

    If a hormone herbicide like 2,4-D is used, remember that there is always the potential for off-target drift that might affect other susceptible crops in the area.  So, be careful and monitor local environmental conditions that could promote the off-target movement of the product.  With all of the lint on the ground this year, a significant rain event will likely generate sprouting cotton seedlings in many fields, possibly allowing floating lint/seed to be washed into ditches and creeks, so we all need to be aware of this potential problem and destroy these seedling when they begin to emerge. If we do not receive a good rain this summer or fall, we should expect to be fighting volunteer cotton in these fields next spring.  For additional information on managing volunteer cotton, refer to http://varietytesting.tamu.edu/cotton/#harvesting

At this web site scroll down to the Weed Section and then select the link for Managing Volunteer Cotton in Grain Crops. 

As we work to wrap up another cotton crop, it is important to remember that without an effective cotton stalk destruction program here in South Texas, boll weevil eradication cannot be accomplished!

COTTON HARVEST AID RESULTS

Here are the seven day ratings  (TABLE 1) for the Cotton Harvest Aid Trial that was established on the Claude Otahal Farm on June 26, 2012.  The cotton variety is FM 835 LLB2 and was treated at 20% open boll with a mean plant height of 21 inches..  The spray application was made between 11 am and 11:30 am with a spray volume of 11 gal per acre @ 32 psi with Turbo TeeJet 11002 spray tips.The harvest aid application was made with a Spider Sprayer by Gary Schwarzlose of Bayer CropScience.  Ratings were made by Dr. Dan Fromme, Extension Agronomist and myself.

The cotton was severely drought stressed at time of harvest aid application.  A rainfall event July 1 yielded 1.6 inches on the field.

Table 1. Comparison of treatment rates and estimated cost per acre, 7 days after treatment, Otahal Farm, Nueces County, 2012.

Trt No.	Treatment	Product Rate per acre	Estimated Cost1	Defoliation (%)	Desiccation (%)	Green Leaf (%)
1	Thidiazuron Non-ionic surfactant (NIS)	1.6 fl oz 0.25 % v/v	$1.82	30	0	70
2	Thidiazuron NIS	3.2 fl oz 0.25 % v/v	$3.59	40	0	60
3	Thidiazuron Def NIS	1.6 fl oz 4.0 fl oz 0.25 % v/v	$3.66	70	5	25
4	Thidiazuron Def NIS	1.6 fl oz 8.0 fl oz 0.25 % v/v	$5.50	80	5	15
5	Ginstar NIS	3.0 fl oz 0.25 % v/v	$5.44	30	0	70
6	Ginstar Crop oil concenrate (COC)	3.0 fl oz 1.0 % v/v	$5.50	87	3	10
7	Ginstar Ethephon NIS	3.0 fl oz 24.0 fl oz 0.25 % v/v	$10.72	70	3	27
8	Thidiazuron Ginstar NIS	1.6 fl oz 2.0 fl oz 0.25 % v/v	$5.42	30	1	69
9	Thidiazuron Ginstar Ethephon NIS	1.6 fl oz 0.8 fl oz 24.0 fl oz 0.25 % v/v	$8.54	70	10	20
10	Aim Ethephon COC	1.0 fl oz 24.0 fl oz 1.0 % v/v	$7.05	19	1	80
11	ET Ethephon COC	1.5 fl oz 24.0 fl oz 1.0 % v/v	$9.42	14	1	85
12	Gramoxone Inteon NIS	8.0 fl oz 0.25 % v/v	$2.04	39	1	60

¹Estimated cost is for educational purposes only and prices listed are not actual “carry out” prices.

 

Trade names of commercial products used in this report is included only for better understanding and clarity. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by Texas AgriLife Extension Service and the Texas A&M University System is implied. Readers should realize that results from one experiment do not represent conclusive evidence that the same response would occur where conditions vary.

NITRATES – A CONCERN IN DROUGHT STRESSED CROPS

            Drought-stressed crops like grain sorghum and corn may result in the accumulation of nitrate at levels that are toxic to livestock.  This may be amplified when high rates of nitrogen fertilizer were applied prior to the stress period.

            Nitrate toxicity is often associated with sorghum hybrids, sudangrass, johnsongrass, sorghumsudan hybrids, corn, and carelessweed (pigweed).  If you produce or plan to use any of these crops for hay, testing for nitrates is strongly recommended when the crop is produced under conditions of moisture stress.      Many samples from the local area have already been sent to the lab and the latest lab results indicate that nitrate levels have been ranging from 0.01 to 1.08, with the average being 0.19 % nitrate.

            Research at the Texas Veterinary Medical Diagnostic Laboratory at Texas A&M University has found that it is safe to feed forage containing up to 1 percent nitrate (on a dry-matter basis) to healthy ruminants.  Forage with a higher percentage of nitrate could be fed if it is ground and mixed with low nitrate forage to reduce the overall nitrate levels to less than 1 percent (dry-matter basis).  Forage containing 0.5 to 1 percent nitrate should not be fed to weakened cattle unless your veterinarian has approved it.  The 1 percent nitrate level assumes that cattle are healthy, well-conditioned, and being fed a high-energy diet.  An online reference regarding Nitrates and Prussic Acid in Forages can be found at the web site; https://agrilifebookstore.org/ by typing E-543.

            If forages contain too much nitrate the animals cannot complete the conversion

process to protein and nitrite levels build up.  The result is the formation of methhemoglobin which can cause an animal to die from asphyxiation, or lack of oxygen.  The animal’s blood turns brown instead of the normal bright red.

            When sampling for nitrates, it is important to remember that nitrate accumulates in the lower stem, and the least is found in the leaves.  If sampling corn, grain sorghum, and sorghum-sudangrass standing forage, create a composite sample from plant parts taken from at least 10 to 15 areas with the same fertility and moisture conditions.  Do not mix plants from “good” and “bad” parts of the field. Create different composite samples for these areas.  Ship samples to the laboratory in clean paper sacks. Do not use plastic bags because the high moisture content will cause the samples to mold, which interferes with the nitrate analysis.

            To sample corn, grain sorghum and sorghum-sudangrass in bales, the bale must be split open and the lower stems of individual plants must be collected. If the bale is going to be ground before it is going to be fed, then representative core samples can be taken with a bale probe.

Samples can be submitted to the Texas AgriLife Extension Service Soil, Water,

and Forage Testing Laboratory. Submittal forms are available online at http://soiltesting.tamu.edu

Damaged Sorghum Heads - Stress Related

 The drought of 2011 has continued into 2012 in South Texas and the lack of soil moisture along with above normal temperatures has resulted in some significant stress on some grain sorghum plants.  As a result seed formation was hampered as seen in the attached photo and is likely related to stress in the sorghum plant. This symptom is  consistent with heat stress during panicle (head) formation while the developing heads are still wrapped up in the stalk surrounded by leaf sheaths.  Most fields did not have excessive damage from this "heat blasting", so if 20% of the field was impacted, with 20% of the head affected, one would expect about a 4% grain loss.  A greater grain loss will occur from simply a lack of soil moisture.