Specialists Speaking - June 2008
Making Up For Lost Time
Although our cotton planting was behind schedule, it should be noted that we have been in this position before. We have had much greater rainfall than normal this year compared with last year. The most important advice is to make more observations during the early season.
When we have cool wet soils, seedlings need to be checked for seedling disease. Even though producers have used seed treatments, when seedlings are exposed to prolonged adverse conditions, even the best treatment may not be enough.
Colder than normal temperatures put seedlings under greater stress, and sensitive areas such as cotyledons and taproots will often be injured. In addition, this problem can be compounded for producers who have used dinitroanilin herbicides.
Under the cool conditions, seed don’t germinate as quickly, and the plant growth and development will take longer.
Ascochyta, or wet weather blight, tends to be more of a problem under these conditions. Although this blight is usually more of a nuisance, it can take out already weakened plants.
On our sandier soils, we always need to worry about leaching of both nitrogen and sulphur. The symptoms are very similar. To tell the difference, a petiole sample can be sent for analysis. In some cases, a few years ago, plants were found to have both deficiencies. The sulphur deficiency can be remedied if the roots grow into areas with adequate sulphur, or sulphur is applied. Nitrogen can also be applied to stimulate growth if it is needed.
Better moisture conditions in 2008 have led to better stands and a more uniform crop than in the past two years. However, with corn and small grain acreage up in the state, we have more stinkbugs and thrips moving out of the small grain and corn, resulting in more potential problems for early fruit set and potential boll damage later on.
Early planted cotton will be squaring in June as the stinkbugs are building up in corn. Much of the damage from stinkbugs will not be apparent until boll opening when damaged locks fail to fluff out. Many producers are trying new BGIIRF varieties, and the management will be different from DPL 555 – especially in controlling vegetative growth.
Best management for any cotton variety is to get early fruit set, which helps control growth and can reduce the amount of growth regulator needed, as well as shorten the time to maturity. Earlier maturity, in turn, will reduce potential pesticide and irrigation needs.
Most of the nitrogen needs of the crop should be met during the month of June as the cotton is squaring, and no nitrogen should be applied later than the third week of bloom.
Despite dry soil conditions in May that are not uncommon in Georgia, progress toward planting the intended one million acres (or just over) of cotton is on target. Even with record high fertilizer costs, many producers apply a base N-P-K fertilizer after getting an adequate stand.
The next challenge in producing high yield cotton will be to supply adequate amounts of nitrogen during sidedress applications. Even where chicken litter was used as a preplant fertilizer, sidedressing with commercial fertilizer nitrogen is important to meet the increased cotton crop demand for nitrogen before peak bloom.
A number of “enhanced efficiency” fertilizer additives are currently available to the Georgia cotton producer, mainly designed to improve the uptake efficiency of fertilizer nutrients that are applied. Urease inhibitors and nitrification inhibitors are the two main materials currently available aimed at increasing uptake of sidedress N applications.
Urease inhibitors will especially have value under dryland, strip-till conditions, whether using granular urea or liquid nitrogen that contains urea. Nitrification inhibitors are thought to be more valuable under irrigated and/or heavier rainfall conditions on sandier land that is prone to nitrate leaching. Using the proper total N rate and timing of applications, namely split applications, can have as much effect or maybe even more when it comes to supplying the cotton crop with the nitrogen it needs.
Dryland fields that have a lower yield potential generally require less nitrogen, and sidedress rates may be adjusted in-season according to up-to-date yield projections. Preplant nitrogen applications on June-planted cotton following wheat taken for grain may be critical to compensate for tie-up of soil nitrogen if the wheat straw remains in the field.
Baling and removing wheat straw removes a significant amount of potassium (up to 100 pounds of K per acre). Burning wheat straw before planting cotton creates a loss of nitrogen and carbon, but fortunately most of the potassium remains in the field in the ash.
Cotton planting in Mississippi is well behind as of May 15. Approximately 20 percent of our acres have been planted compared to a five-year average of nearly 75 percent. Areas in north Mississippi were wet nearly all spring, whereas areas in the south Delta region have received less frequent rainfall with some cotton producers having 80 to 90 percent of their acreage planted.
However, reports of replanting cotton have been coming in due to poor emergence and/or poor growth. Italian ryegrass has been a significant problem in Mississippi this spring. Many Delta fields, not just cotton fields, are infested with ryegrass. We do have glyphosate-resistant Italian ryegrass in the state; however, I do not think that all of the escapes are due to herbicide resistance.
Extremely wet conditions in the spring have delayed burndown applications, allowing ryegrass to grow to the point that control with a single herbicide application is difficult. Research from the Delta R & E Center at Stoneville indicates that sequential herbicide applications are necessary to control ryegrass in the spring.
If ryegrass has been a significant problem in your field this spring, consider using a fall-applied herbicide (this year) for control. However, keep rotation restrictions in mind if your planting intentions for a given field change after you have made the fall herbicide application.
Also, consider how much spring tillage you are willing to do if your seedbeds weather and need to be reformed due to reduced cover from weeds. We need to take a snapshot in our mind of fields infested with Italian ryegrass this spring and begin planning now to control the problem either this fall or next spring.
The cotton crop in Arkansas is off to a slow and poor start. Numerous rain showers and cooler-than-normal temperatures have kept equipment out of the field and seed in the sack until late May. This is one of the toughest springs for cotton planting that I have experienced.
The planting has been spread out over a two-month period because for every two days of good weather, there would be five days of rain and cold temperatures. As a result, the cotton planted earlier is really struggling, fighting off stresses of cold weather, no sunshine, diseases and thrips populations.
Seedling disease has been a big problem this year due to weather conditions and added stresses associated with thrips populations. We will have more late planted cotton across the state than ever before. There are many Arkansas producers who have planted cotton later than they ever have. Cotton that was planted past May 20 for northeast Arkansas and May 25 for southeast Arkansas may lose yield potential, depending on the fall weather conditions.
Later planted cotton will have to be managed intensively to prevent further delays into the fall. Fruit retention will be much more important on the later planted cotton and should be monitored closely.
According to reports from seed dealers, cotton acre-age in northern Alabama will be well below 100,000 acres this season. In fact, it may be in the 70,000 to 80,000 range, even including the acreage right across the state line into Tennessee.
Considering just a few years ago Limestone County alone had more than 70,000 acres of cotton shows what dramatic changes are occurring in the farming community in northern Alabama. For the first time since the early 1980s, soybean acreage in Alabama will be greater than cotton.
What caused these changes include two terrible cotton crops due to drought and the high fixed costs of dryland cotton production due to high technology and seed costs. Recent record high prices for grain crops of wheat, corn and soybeans coupled with their lower production costs made changing from cotton an easy decision for most farmers.
Will cotton return to more normal acreage in the next few seasons? That is the big question cotton gins, cotton warehouses, equipment dealers and all agriculture suppliers are asking. Cotton depends on this infrastructure, and, if it closes down, cotton acreage will be difficult to return.
Presently, technology fees charged to Alabama cotton farmers are a fixed cost no matter what cotton yields are made. Unless cotton prices increase dramatically or technology companies realize they must share some of the risk during drought seasons, things do not look good for cotton’s return.
Hopefully, 2008 will be a wakeup call for many in the cotton industry that the whole variable fee system charged for cotton technology needs adjusting, especially for dryland cotton farmers.
June is a time to check the growth rate of fields where you might suspect excessive growth. Typically, we are more successful in controlling growth with mepiquat on fields with potentially rank growth if we can make a mepiquat application at the 9- to 10-node stage instead of waiting until the bloom period to make our first mepiquat application.
Measure the longest of internodes below the third and fourth mainstem leaves. This internode is a good indicator of current conditions for future growth. If this internode is longer than you would like (2 to 2.5 inches), you should apply mepiquat if soil moisture is good. Use the lower threshold (2 inches) if you are dealing with a field with high moisture-holding capacity where you have seen rank growth problems in the past.
I would use the higher threshold (2.5 inches) on most of our sandier cotton soils with lower water-holding capacities.
The second generation budworm that has typically been a problem for some fields in the past during June is not much of a problem anymore due to Bt varieties. Thrips problems typically tail off during the first week or two of June. The most likely pests for June are plant bugs, spider mites and sometimes early cotton aphids. These typically are more sporadic pests for us.
Most of the Arizona crop has experienced a strong start to the 2008 season. Variability in temperatures during the spring planting season has resulted in some replanting, particularly in the southeastern part of the state.
The crop overall is slightly behind normal this year, but things have begun to warm up significantly, causing the crop to surge forward in development. Early season fruit set has begun with squares and some early flowers being seen across the state. Protecting this early season fruit set is critical to achieving optimum yields, while enhancing a timely termination of the crop in the fall.
Loss of this fruit set may result in excess vegetative growth, delayed maturity and decreased yields. Abortion of young fruiting forms, such as small squares and young flowers, may occur as a result of several factors, including environmental stresses such as hot dry winds or lack of adequate soil moisture and early season insect pressure.
The past two years have seen record low insect populations across the state, and we have greatly benefited from the ability to manage our cotton crop with minimal insect control measures. However, it is important to keep in mind the old saying that “past performance is no measure of future results.”
It is critical to monitor the crop for the presence of insect pest populations, ensuring that they do not rise to damaging levels in the crop.
Scouting techniques and control measures have been developed for major pests affecting Arizona cotton and can be found on the University of Arizona’s Crop Information Site (ACIS).
Folks continue to have interest in the use of mepiquat-based plant growth regulator products. It’s hard to be-lieve, but BASF registered PIX more than 28 years ago! Since that time, there have been several mepiquat products brought to the market. Recently, BASF (Pentia – mepiquat pentaborate), Bayer CropScience (Stance – mepiquat chloride + cyclanilide) and Dupont (Mepex GinOut – mepiquat chloride + kinetin) introduced new products. All these products perform a similar function in that they reduce gibberellic acid synthesis in cotton plants.
The reduction in gibberellic acid results in reduced cell expansion and thus shorter internode length. We’ve evaluated mepiquat products extensively and our best management scenario occurs when the initial application comes before bloom, in the match-head to third-grown square stage.
Many cotton producers and practitioners prefer to wait until the early-bloom stage to make the initial application, and there’s nothing inherently wrong with that type of approach. However, our experience indicates that, generally, it’s more difficult to manage the crop and may require higher rates to achieve desired results (especially under irrigated or high rainfall conditions).
It has been a much better season so far in our state this year when we consider the last two record-setting droughts. It has been our observation this season that planting has been slightly behind previous years, possibly due to fewer acres being planted and the cool temperatures experienced in the latter days of April.
This year’s crop brought the usual insects during planting, emergence and early season growth. According to Dr. Ron Smith, Extension entomologist at Auburn University, many central and south Alabama producers treated for cutworms and grasshoppers in their burndown applications or following planting.
Cotton insect scouting schools will be held in early June again this season. The dates are as follows: June 10 at the Autauga County Agricultural Center; June 11 at the Wiregrass Research and Extension Center; and June 18 at the Tennessee Valley Research and Extension Center. All insect training events will begin at 8:30 a.m. No pre-registration is required, and no registration fee will be charged.
Those in the state who are interested in precision agriculture techniques will have an opportunity to learn more about it this summer. Plans are underway for a field day that will be held on July 10 at the Isbell Farm in Colbert County of northwest Alabama. More information is available through the ACES Precision Agriculture Program at (256) 256-353-8702, extension 26 or 28.
Much has been said and written about the emergence of former secondary insect pests as primary insect pests in Mid-South cotton. Boll weevil eradication and Bt cotton have created a production environment in which plant bugs and stinkbugs now dominate the insect pest management discussions.
This is all true. But for many cotton producers, in the heat of battle, the most important insect pest is the one that they have now. By default, we manage around and try to solve problems as they arise. It may be thrips today, plant bugs tomorrow and armyworms next week. For the most part, that is the way our recommendations are developed.
A cotton crop, however, is an extremely complex system and screams to be managed as whole and not in part. The examples of this are numerous. The management of early season insect pests is intertwined with weed control in early spring burndown. Management of rank growth is linked to fruit retention, which is related in part to insect feeding. In turn, insect pressures are often different from one field to the next based on proximity to wild hosts and adjacent crops. The list can go on and on.
Whether you call it integrated pest management, farmscape management, or any other name, we have to continue to learn as much as we can.