Cotton Newsletter

Crop Conditions Seed Supply The Do=s and Don=ts of Using Starter Fertilizers Manganese Nutrition for Cotton Equipment Calibration Is Critical for Nematode Control Burndown Weed Control Need for Untreated Check in RR Cotton Cotton Scout Schools Early Season Thrips and Dry Weather Cotton Quality Trends and Losses in GeorgiaBThe Good, The Bad, and The Ugly 1999 Boll Weevil Assessment New Extension Weed Scientist Calendar

Crop Conditions. (Brown) Less than 15 percent of expected acreage in Georgia is planted as of April 21. The southern fourth of the state is extremely dry, so much so that planting and tillage have ceased. With each passing day, the moisture situation is becoming more critical. Until this past week, soil temperatures have been favorable for rapid germination, but the cool snap gave an additional reason for a brief delay in planting.

Seed Supply. (Brown) Varietal choices and seed supplies are tight in some places but ample in others. A few dealers have offered carryover seed, seed that was bagged and marketed in 1997 or 1998. Without a current germination and quality test, such seed should be avoided!

The Do=s and Don=ts of Using Starter Fertilizers. (Harris) Although starter fertilizers are not routinely recommended for Georgia cotton, they can be helpful in certain situations. There are also some situations where misuse of starters can be a waste of time, money and even hurtful to the crop. The following is a list of do=s and don=ts to help with decisions when using starter fertilizers on Georgia cotton.

Do consider using starters for early-planting, conservation-tillage or high-yield situations.

Do use the recommended A2 x 2" placement ( 2 inches below and 2 inches to the side of the seed).

Do consider using phosphorous-containing starters (such as 10-34-0) on most sandy Coastal Plain soils and Ared@ soils, sulfur-containing starters on deep sands, and nitrogen-only starters on soils testing very high in phosphorous.

Do consider spiking liquid starters with micronutrient packages containing manganese or zinc if soil test results indicate a need for either of the elements.

Do account for the nitrogen and phosphorous in starters in your total fertilizer program or nutrient management plan.

Do consider broadcasting some phosphorous fertilizer when starters have been the only method of providing phosphorous in a long-term conservation-tillage system.

Don=t deep place a starter behind the subsoil shank or spray a starter in a band over the row. You will lose the advantage or Astarter effect@.

Don=t dribble a concentrated band of starter fertilizer directly over the row (seed).

Don=t place any starter fertilizer in furrow under any circumstances.

Don=t exceed more than 15 lb N/A even in the 2 x 2 placement.

Don=t worry about adding potassium or sulfur to starters if you can include these nutrients in preplant, broadcast fertilizer.

Manganese Nutrition for Cotton. (Harris) A popular question during this winter meeting season involved the need for manganese fertilizer for cotton production. The UGA soils committee recently voted to totally drop the recommendation of 2.5 lb Mn/A when soil pH is greater than 5.6. This was due to lack of research supporting the need for the recommendation. However, this does not mean that manganese deficiency on cotton can not occur. In fact, the combination of a low soil test manganese and a high pH warrants concern. For example, at a soil pH of 6.0, soil test manganese should be at least 5 lb/A. At ph of 6.5, soil test manganese levels need to be around 10 lb/A. These guidelines can be found in the UGA Soil Test Handbook For Georgia on page 47. These guidelines were generated more with soybeans in mind but should also be good for cotton.

One private soil testing lab in Georgia is still recommending broadcast Mn fertilizer rates well above 2.5 lb/A (up to 20 lb/A). This is obviously expensive. In their defense, a statement on the back of the soil test report indicates this may be expensive and suggests the option of using lower rates of Mn applied in with starters and/or foliar applications. Both of these methods of Mn fertilization are acceptable. The best strategy to avoid Mn deficiencies and at the same time keep a close watch on economics is to 1) identify potential problem fields that have the combination of low soil test Mn and high soil pH (for example, a soil test Mn level of 4 and a pH of 6.6), 2) tissue test at first square to confirm a Mn problem, and 3) if a Mn problem is confirmed with tissue testing, foliar feed as needed (tissue testing can also confirm if the problem was avoided by using Mn in a starter).

Equipment Calibration Is Critical for Nematode Control. (Davis) Using the correct application rate is critical for the effectiveness of any agricultural chemical, and nematicides are no exception. Regardless of which nematicides you may use, an incorrect rate will cause economic loss because 1) nematodes will not be adequately controlled if the rate is too low, or 2) you applied more nematicide than necessary to achieve adequate nematode control. Fortunately, this is one problem that is relatively easy to avoid if you spend the time required to check the calibration of your application equipment.

There are many ways to calibrate equipment, and different people use different methods. But even though calibration methods may look very different, they all work on a similar principle: they all measure the amount of chemical applied to a specified area of the field, and then adjustments are made until the output achieved is the same as the desired output. Two simple methods for measuring Temik and Telone II output are given below. Both methods were provided by the manufacturers. Refer to the Georgia Pest Control Handbook or the Georgia Cotton Production Guide for recommended nematicides and nematicide rates. Temik and

Telone II are the focus of this article because they are the most commonly used pre-plant and at-plant nematicides in Georgia, but other nematicides also are used.

The simplest method to calibrate Temik output is to get Acalibration tubes@ from a Temik representative or chemical dealer. The tubes come with instructions printed on them and two charts: one for the gypsum formulation (small black granules that come in Lock >n Load containers or 45 lb boxes) and one for the corncob grit formulation (gray granules in 30 lb bags). The tubes are used to catch the amount of Temik applied as the tractor travels 200 feet at normal operating speed. The appropriate chart will tell you how much Temik you should have collected in the calibration tube based on the row spacing you use and the desired lb/A. Compare this amount to the amount you actually collected and either increase or decrease the output until you achieve the desired application rate.

Calibrating Telone II output should be done with water instead of the nematicide to increase operator safety. Determine the distance to drive from the chart on page 4. Measure the number of seconds required to drive that distance with all equipment attached and operating. Maintain this throttle setting during calibration and Telone II application. Collect water from one nozzle for the amount of time it takes to drive the required distance. The oz of water collected equals the gallons of water applied per acre. You will actually get 10% less Telone II per acre than you would water, so divide gallons of water per acre by 1.1 to determine the amount of Telone II applied in gallons/acre. You can adjust orifice size, pressure, or tractor speed to apply the desired rate of Telone II. An example is given in the following paragraph.

If you have one nozzle every 38 inches, the following chart tells you to measure the amount of time required to travel 107 feet. Then collect water from one nozzle for the amount of time it took to travel 107 feet. If you collected 3.3 ounces of water, you would be applying 3.0 gallons of Telone II per acre (3.3 ounces of water equals an output of 3.3 gallons of water per acre; 3.3 divided by 1.1 equals 3.0 gallons Telone II per acre). This same method can be used for other desired rates of Telone II.

Telone II Table. For Telone II calibration, measure the amount of time it takes to travel the distance given in this chart that corresponds to your nozzle spacing. This table is based on one outlet per row.

Burndown Weed Control. (Brown) Conservation tillage occupies approximately 15 percent of the Georgia cotton acreage. Eliminating vegetation present prior to cotton emergence is critical in reduced tillage systems. The 1999 Georgia Pest Control Handbook (pg. 40-41) and the 1999 Georgia Cotton Production Guide (pg. 46-47) include a weed/plant response chart to burndown herbicides.

In March and April, non-tilled fields often have a very diverse complement of cool season annuals. Some are hard to identify; others we=ve become quite familiar with, even in the rosette stage. Some species pose a serious competitive threat to emerging cotton and absolutely must be exterminated, while others warrant little concern because of spindly, non vigorous growth. In late April, summer annuals appear, adding to the complex of weeds that must be controlled.

Dry weather is limiting the efficacy of burndown treatments. In response to stress (extremes in temperature or moisture), activity of Roundup declines more rapidly than the activity of Gramoxone. With persisting dry weather, tank mixtures with other herbicides become even more important.

Cutleaf eveningprimrose, a hard-to-kill cool season annual, has been among the most prevalent weeds this spring. Roundup alone provides inadequate control of primrose, but the addition of diuron (Karmex, Direx) improves activity. The activity of Gramoxone alone, though superior to Roundup on primrose, is also enhanced with the addition of diuron or cyanazine (Bladex, Cy-Pro). Because of potential antagonism related to initial foliar burn and reduced uptake, Roundup/cyanazine mixtures are not recommended. When diuron is used in burndown mixtures, slight reductions in preemergence rates of fluometuron (Cotoran, Meturon, etc.) may be needed to prevent injury if planting follows within a few days after application.

Combinations of Gramoxone plus cyanazine have performed well on primrose, ryegrass, and a host of other weeds. In burndown treatments, cyanazine applications should be limited to 1 pt/A and should be made at least 7 days prior to planting. Cyanazine treatments are prohibited on coarse soils (sands and sandy loams) and those with less than 1 percent organic matter. In questionable situations, increasing the interval between application and planting improves safety.

Another treatment that has provided excellent results in growers= fields is Roundup plus 2,4-D. Product labels of 2,4-D are rather nebulous but research indicates that an interval of 4 weeks between application and planting negates the risk of injury from 2,4-D.

Two Anew@ products have been added to the burndown arsenal, Touchdown and Clarity. Touchdown contains the active ingredient sulfosate, which is very similar to glyphosate, and is formulated as a 5.0 lb/gal trimethyl sulfonium salt of sulfosate. There is indication that the product dissociates (the acid and salt separate) and forms the acid glyphosate within treated plants. However, distinctions exist in activity of Roundup and Touchdown. Touchdown may seriously injury RR cotton. Visual effects following Touchdown treatment often occur sooner than with Roundup, though usually the final control is similar. In several tests this spring, Touchdown combinations provided slightly better results than Roundup combinations. The overall consensus is that Touchdown is as good as Roundup and is sometimes a little faster. Keep in mind that the Touchdown label presently requires an interval of 35 days between application and planting cotton.

Clarity is basically a low-volatile formulation of dicamba (Banvel). In a few trials this spring, addition of Clarity improved the activity of Roundup and Touchdown on cutleaf eveningprimrose. An interval of 21 days is required between application and planting.

Need for Untreated Check in RR Cotton. (Brown) There have been several questions about the effects of Roundup on RR cotton. Problems such as root abnormalities, boll shed, wilting, etc., have occurred in fields with RR cotton. In most instances, this has had little to do with the herbicide, but there have been a few cases not easily dismissed as variety issues. As a diagnostic tool, growers can simply cut the sprayer off for a few feet in RR cotton in order to separate varietal effects from herbicidal effects. Obviously, untreated areas should be minimal (perhaps one sprayer width by 10 feet is enough) to avoid significant losses due weeds.

Cotton Scout Schools. (Roberts) An efficient insect control program begins with a good scout. To maximize profitability, good decisions must be made concerning insect control. The failure to apply a needed spray is costly and application of an unneeded spray may be just as costly in the long term. Scouts provide the necessary information for decision making and scout schools are being offered at several locations in the upcoming weeks. If you are interested in attending a scout school, contact your county agent for more information. Locations and dates are listed below.

Early Season Thrips and Dry Weather. (Roberts) Thrips are an annual pest of cotton seedlings in Georgia. Although little cotton has been planted to date, fields should be monitored for thrips at least weekly until the four to five leaf stage, regardless of whether a preventive insecticide was used at planting. Historically, we have seen more problems from early season thrips in drought-stricken fields. Under these conditions, available soil moisture may drop below the insecticide treated zone and thus plants are not able to take up insecticide and are vulnerable to thrips. Thrips damage cotton by feeding on young, unfurled leaves. This causes the expanding leaves to become crinkled and distorted. Plants can recover from some injury if growing conditions improve, but severe thrips damage can delay plant growth or even kill young seedlings.

To scout for thrips randomly select a plant and beat it against a stiff sheet of white paper, a cigar box, etc. Multiple spots should be checked in a field. Treatment with a foliar insecticide is recommended if 2-3 thrips per plant are found; especially if numerous immature thrips (wingless) are found. The presence of immature thrips suggests that insecticide control is not being achieved. Low rates of dimethoate, Bidrin, or Orthene (acephate) are effective foliar treatments if threshold levels of thrips are detected.

Cotton Quality Trends And Losses in Georgia-- The Good, The Bad, And The Ugly. (Shurley) The past few years have not been Ashining stars@ when it comes to the fiber quality parameters of Georgia=s cotton crop. However, we are not alone. Quality of much of the US crop has suffered during the past few years. However, over the past 10 to 15 years, significant quality improvements have occurred across the Belt, and our ranking as producers of high quality cotton has improved, particularly in terms of fiber strength. Still, there are trends that need attention.

As the following table shows, one disturbing statistic is the high number of bales not grading Color 41 or better. The majority of these bales are Alight-spotted@ gradesB 32's and 42's. While this can largely be caused by weather (excessive rain during harvest), it challenges us to consider if there are any management and/or cultural practices that can be improved. Fiber length (staple) and strength have also declined during the past couple of years, presumably due to drought during the season and rainfall during harvest.

Extraneous Matter (grass and bark) has declined since 1995. Low micronaire bales have also been reduced. High micronaire (above 4.9) continues to be a challenge, particularly on non-irrigated acreage. While this is largely weather related, many of the new higher-yielding varieties tend to be in the upper level of the acceptable micronaire range even under normal weather conditions.

The table on page 8 shows estimated dollar losses from grade discounts on the 1998 Georgia cotton crop. Almost 46 percent of the >98 crop was discounted for Color. Losses totaled over $15 million. Almost 28 percent of the crop was discounted for short fiber length (staple). Much of this was 33/32nd=s compared to the base grade requirement of 34/32nd=s ( 1 1/16th inch).

Total quality losses on the 1998 Georgia crop are estimated at $26.4 millionB $17.48 per bale or $19.72 per acre. Arguably, some losses are due to weather and growing conditions and may be largely unavoidable. But we must carefully consider how production inputs, management decisions, ginning, and handling each influence quality.

1999 Boll Weevil Assessment. The base fee for the 1999 Boll Weevil Eradication Program is $2.50 per acre. Intended acres must be reported to local FSA offices on or before May 1 to avoid penalties.

New Extension Weed Scientist. (Brown) Dr. Stanley Culpepper, who recently completed his degree at NC State University, is expected to join the UGA Extension faculty on May 5. He will focus on weed science educational programs in cotton. Dr. Culpepper will be located in Room #226 at the RDC in Tifton and can be reached at 912/386-3194.