UGA COTTON NEWSLETTER
June 28, 2000
Crop SituationSidedress Nitrogen - Burn and Volatilization Concerns
Don't Forget To Apply Boron
Choosing a Layby Treatment for Roundup Ready Cotton
Replacing Cyanazine (Bladex, Cy-Pro) Effectively and Economically
E-Commerce Moves into Agriculture
Crop Situation. (Brown) The Boll Weevil Eradication Program tally on intended plantings in Georgia as of May 1, 2000, was 1,550,791 acres. The number of certified acres will be finalized soon, but the question remains, AHow many cotton acres will we really farm?@ We believe the number is as low as 1.2 or 1.3 million acres. Significant dryland acreage will be abandoned because of nonexistent or extremely poor stands. Recent rains have significantly revived many non-irrigated fields but many others are essentially a total loss. The key factor affecting crop potential is stand. Nonirrigated fields in which reasonable stands exist have good prospects, if they receive sustained moisture. As we move into bloom, water demand increases considerably.
Growers dealing with terrible losses have been frustrated with crop insurers. Federal Crop Insurance regulations require that fields be continued at 25 days beyond the last date of planting, which is May 31. As of June 26, 2000, insurers were in a position to release qualified fields. The next several weeks will determine how many acres we destroy.
Monsanto extended the crop loss deadline on Roundup Ready and Bollgard cotton to July 15 or 60 days after planting, whichever is later. Technology fees will be refunded for cotton affected by extreme drought and that is destroyed by the dates listed above.
Again, as scattered showers continue, cotton prospects improve but will ultimately be determined by rainfall in July and August.
Sidedress Nitrogen - Burn and Volatilization Concerns. (Harris) Which is better, dry or liquid fertilizer? This is a popular question to which there is no correct answer. Both dry and liquid fertilizers can work well when used properly. Both can also have disadvantages. For example, numerous reports of ammonium nitrate burn on topdressed cotton have been received this year. The problem is usually worse on the two rows directly under the center of the spreader truck where more Afines@ are distributed. Dry weather and stressed cotton are also contributing factors to this problem. Although the damage can often appear severe, cotton usually grows out of this situation with little yield effect. Liquid nitrogen sidedress can also burn cotton, usually on lower leaves where it splashes or comes in direct contact. This can be more of a problem on younger (i.e. smaller) cotton, although again, the effect is usually both temporary and minimal.
Dry weather has again caused a lot of concern over volatilization loss of sidedress N materials. As stated in the previous newsletter, a lot of this concern is probably unwarranted. Granular (dry) urea is the N fertilizer to be most concerned about, especially in conservation-tillage where it can get hung up on residue. In humid climates, urea undergoes a process called hydrolysis where ammonia gas is formed and can escape into the atmosphere. This process does require some moisture. If the soil is extremely dry, basically no loss occurs. If the soil is moist, loss is minimal. The worst case is when the soil is dry and then just enough moisture is received (a light shower or a number of heavy dews) to fuel this reaction but not Awash@ the urea into the soil. Ammonium nitrate does not undergo hydrolysis like urea and therefore volatilization losses should be minimal. Most liquid N solutions (e.g. 28 %, 32 % etc.) are made up of urea and ammonium nitrate (AUAN@) where half of the nitrogen comes from urea . However, UAN solutions are usually Adribbled@ on in a concentrated band directly on the soil surface. This minimizes volatilization losses greatly compared to broadcasting granular urea.
Even under dry conditions, volatilization loss of sidedress N fertilizers is probably less than 5 %. If there is not enough moisture in a three week period to Awash@ in the fertilizer, the yield potential is probably not there either. Also, Aplowing in@ sidedress N probably does more harm from losing soil moisture and pruning roots than it does to save nitrogen.
Don=t Forget To Apply Boron. (Harris) The window to apply foliar boron is the same as sidedress N - first square to first bloom. The recommended rate is 0.5 lb B/A, preferably in two, 0.25 lb B/A applications. This is more of a challenge in Bt and Astacked@ cotton where early Pix and the occasional insecticide spray are the only opportunities to tank mix boron. The full 0.5 lb B/A can be applied at one time, especially if the cotton is not stressed. Burn is an issue if the cotton is stressed or if more than the 0.5 lb B/A is attempted. Is it worth the trip to apply boron alone? If no preplant B was applied, the soil is sandy and moisture is adequate - yes. Otherwise, try hard to tank mix it.
There are a number of good boron fertilizers available. The standard for many years has been solubor, a wettable powder formulation containing 20% B. The product is now available as solubor DF which contains 17% B. Liquid borons cost a little more but are probably the easiest to handle. Most liquid borons are derived from boric acid. Although >acid@ is in the name, it is a weak acid and does not affect the pH of the tank water significantly. Boric acid is also now available as a granular material. It mixes about the same as the Solubor DF and appears equally effective. There is at least one boron fertilizer currently available claiming better efficiency, therefore, a lower rate is needed. In the past similar claims have been made, but have been contradicted by research. For now, treat all boron materials as equally effective.
Foliar Feeding. (Harris) Foliar feeding is a good way to supplement a soil-applied fertilizer program and make in-season adjustments according to yield potential. Nitrogen, potassium and boron are the fertilizer elements on which to concentrate. On irrigated fields, foliar feeding can top off a high yield. Anticipating lower yield potential on dryland fields, sidedress N rates may have been reduced. If significant showers have been received and yield potential looks better, foliar feeding both N and K may be helpful.
There are numerous fertilizer formulations available for foliar feeding. This is not a year to go with unproven (Amiracle@ or Asnake oil@) products. AFeed Grade@ urea is a good choice for
foliar N. Potassium nitrate is a good choice for foliar K. As stated in the article above, numerous good boron materials are available. Refer to past year=s Georgia Cotton newsletters for rates and key rules of thumb such as, ADon=t foliar feed drought stressed cotton that is wilted by noon.@
Choosing a Layby Treatment for Roundup Ready Cotton. (Culpepper). Roundup effectively controls most of the more common and troublesome weed species in Georgia cotton. However, morningglory and nutsedge control is often marginal; therefore, in most Roundup Ready cotton fields, a layby application using conventional herbicides may be the best choice. Additionally, several conventional herbicides offer weeks of residual weed control that is not observed when using only Roundup.
Although conventional chemistry is probably the best choice for cotton layby in most Roundup Ready cotton, fields that are heavily infested with large grasses or perennial weed species may warrant a precision postemergence-directed application of Roundup. For growers using Roundup as a layby treatment in Roundup Ready cotton, there are several options to enhance morningglory control and obtain residual weed control. According to the Roundup label, Roundup Ultra may be tank mixed with cyanazine (Bladex, Cy-Pro) or diuron (Direx) at layby: the label suggests mixing Roundup Ultra (2 pt/A broadcast) with cyanazine (0.75 to 1.0 lb ai/A) or diuron (0.75 to 1.0 lb ai/A). Similarly, the Caparol (prometryn) label allows a tank mix of Caparol with Roundup Ultra. Our research has shown that cyanazine, diuron, or Caparol mixed with Roundup Ultra often enhances morningglory control and provides several weeks of residual weed control.
On the other hand, these herbicides (cyanazine, diuron, or Caparol) can reduce activity of Roundup Ultra on grasses and possibly other weed species. Work in 1999 noted 9 to 16% less control of Texas panicum when Roundup Ultra was tank mixed with Caparol, diuron, or cyanazine as compared to Roundup Ultra applied alone. Additional studies are in progress during the 2000 season. Our work suggests that antagonism (reduction in grass control with the tank mix as compared to Roundup Ultra applied alone) may be the greatest with cyanazine and slightly less with Caparol or diuron. Growers applying these tank mixtures are recommended not to reduce the rate of Roundup Ultra and limit the rate of these residual compounds to no more than 0.75 lb ai/A broadcast. Additionally, a favorable environment and small grasses are needed to eliminate the potential for antagonism.
Other options that can potentially enhance the efficacy of Roundup Ultra as a layby post-directed application include tank mixing Roundup Ultra with Harvade or Prowl. Harvade is a relatively new post-directed herbicide that may be tank mixed with Roundup Ultra to enhance morningglory control in Roundup Ready cotton at a very economical price. Prowl does not control weeds that have emerged, but mixing Prowl with Roundup Ultra potentially offers residual control of grasses and small seeded broadleaf weeds (pigweeds, etc.) assuming the Prowl is activated by a rainfall or irrigation within a week. Our research to date has not shown any concerns of antagonism when mixing Roundup Ultra with Harvade or Prowl.
Replacing Cyanazine (Bladex, Cy-Pro) Effectively and Economically. (Culpepper) Although production of cyanazine ceased December 31, 1999, most growers have been able to obtain adequate quantities for their 2000 crop. However, for growers who are unable to obtain cyanazine to layby their cotton crop as well as for those growers who are beginning to prepare for future production without cyanazine, several effective treatments are available.
When considering replacements for cyanazine, three distinct areas of weed control must be considered: 1) postemergence weed control, 2) residual weed control, and 3) crop tolerance. At this time, the most likely replacement herbicides with all three of the aforementioned attributes include prometryn (Caparol, Cotton-Pro) or diuron (Direx, Karmex).
Research in 1999 and 2000 has shown that prometryn plus MSMA, diuron plus MSMA, and cyanazine plus MSMA similarly control most of Georgia=s more common weed species. Although cyanazine treatments often appear to be quicker in controlling weeds, the end results when using prometryn and diuron are usually similar. However, our work does suggest to apply prometryn or diuron to weeds slightly smaller than what growers are used to with cyanazine. Further, cost per given quantity of prometryn and diuron is usually similar to or less than cyanazine in most areas.
Residual weed control is often a benefit in fields that are heavily infested with weeds and when growers are faced with Askippy@ cotton. Cyanazine usually offers a couple of weeks of residual control. Both prometryn and diuron will offer significantly longer residual weed control as compared to cyanazine; the half life (time it takes for half of the chemical to decompose) of prometryn and diuron is 4 and 6 times greater, respectively, than that of cyanazine. Although longer residual control will most likely be beneficial for many growers, always consider rotational restrictions as prometryn and diuron will have a greater potential to carry over to rotational crops.
Cotton is tolerant to cyanazine, prometryn, and diuron when these herbicides are applied following labeled directions; in fact, our research has indicated that prometryn and diuron are often safer on cotton as compared to cyanazine. However, application method and rate of application will determine cotton response to these herbicides.
While the focus of this article is on prometryn and diuron, there are several other herbicides (Harvade, Cobra, Goal, fluometuron) which, under certain circumstances, can also be effective in replacing cyanazine. It is always best to evaluate each situation individually in order to determine the best choice for your weed management system.
E-Commerce Moves into Agriculture. (Brown) Internet purchasing has become much more common over the last couple of years. We are seeing the introduction of Internet marketing in regard to agricultural inputs. The first involves brokerage or auction sites; the second, direct marketing via the Internet; and the third, a means of inventory management.
XSAG.com and FARMBID.com are two (perhaps there are others) websites which provide a medium of exchange for ag products. Buyers and bidders are anonymous, and thus a farmer seeking to purchase XYZ Herbicide may receive bids from dealers, distributors, or possibly even the basic manufacturer. Theoretically, the Internet company is simply a posting site for such commerce. They do not own the product and therefore claim little responsibility beyond the buy/sell agreement and possibly shipping arrangements.
FARMSAVER.com represents another approach to marketing, specifically the direct marketing of ag chemicals. Presently, the company handles only a single product, mepiquat chloride. The company has a generic formulation of mepiquat chlorideBthe active ingredient is produced in China and the finished product is formulated in Tifton. Because of the lack of overhead, the company offers the product at a very competitive price. To compare product performance, we initiated an experiment to evaluate FARMSAVER.com mepiquat chloride along with Pix Plus and another generic mepiquat chloride.
Basic manufacturers are also examining how to use the Internet in marketing and distributing their products. They are wrestling with how to become more efficient and competitive simultaneously with supporting the traditional supply chain.
In terms of e-commerce purchases of ag products, several questions must be worked out.
(1) How easy and reliable is the purchase experience? (2) How reliable and satisfactory is the transportation system which brings the product to the grower? (3) What is the quality of the product received in terms of container integrity, formulation consistency, product efficacy, etc.? (4) When there are problems in the chain of purchase, transport, or performance, how and by whom will those issues be handled?
Competition will have a significant impact on our future. Generally, the presence of generic providers results in cheaper inputs. We are already seeing this concept influence product price in the marketplace. However, as producers purchase generic products, they reduce the economic engine involved in fueling discovery and development of new tools.
CalendarSunbelt Expo Field Day, July 18, 2000, Moultrie, GA
Prepared by:Steven M. Brown, Extension Agronomist-Cotton