- Specialists Speaking -
This Crop Needs To Catch Up
Rainfall has been very short in the eastern part of the panhandle all year long. Many producers dusted in cotton hoping for timely rains. Seldom is natural rainfall adequate for optimum cotton growth and yield. Cotton requires very little moisture for a few weeks after germination but does require good moisture at planting to establish a stand.
Cotton is especially sensitive to moisture shortages during the bloom period, which occurs in July and August in the Deep South. However, effective bloom period for cotton in our region occurs over a period of about eight to nine weeks, and if good weather conditions occur for three to four weeks of that period, good yields are often made. Many producers irrigate with center pivots and may have limited amounts of water – especially if they irrigate from ponds or lakes.
Corn usually needs water earlier in the year in May and June and may deplete supplies or can be a good rotation with cotton since water requirements are at different times (May, June, early July for corn vs. July and August for cotton). If pivots have to be moved, this is a good combination of crops since it can be moved from corn to cotton and remain there.
We found in an eight-year study that rotating cotton behind peanuts after two years of bahiagrass can almost eliminate the need for irrigation since soil moisture and rooting depth of cotton is greatly increased due to root channels left from the perennial grass. Therefore, if irrigation is not available and there is old pasture land that can be taken in, consider planting cotton after perennial grasses or even the second year after grass to take advantage of the rooting depth and extra moisture available.
Keeping perennial grasses in row-crop rotations is very beneficial to farming systems and will accommodate livestock, which can result in year-round utilization of the land.
Although effective and precise irrigation is the focus of this issue of Cotton Farming, the last thing on the mind of Mississippi cotton producers at the time of this writing (May 14) is irrigation. Excessive rainfall brought planting to a screeching halt the first two weeks of May. However, as everyone knows, we are only one missed rainfall away from a drought.
June is a pivotal month in cotton production. Squares will appear, irrigation will begin and weeds and insects will make their presence known. June can also be a month of feast or famine in terms of rainfall. Rainfall totals of less than one inch for the month of June have been recorded in two of the past four growing seasons. June is also the time when irrigation will likely begin. Cotton is very sensitive to drought stress from squaring to peak bloom and in the absence of rainfall, irrigation should be scheduled accordingly. Keep in mind delaying the first irrigation can have a lasting impact upon productivity of a given field.
Irrigated acres in Mississippi have increased from four percent in 1972 to 41 percent in 2008. Cotton yield under irrigation has averaged 31 percent more than dryland. The benefits of irrigation are obvious; however, with increases in the price of diesel fuel and ever tightening restrictions on agricultural water use, we must continue to strive to make the most efficient use of the gifts bestowed upon us.
As of this writing on May 12, the condition of the Louisiana cotton crop is highly variable depending on when it was planted and amount of rainfall received. The majority of the cotton has been planted with only 10 to 15 percent of acreage left to plant. Cotton planted during the mid-April to April 24 period is at the one- to three-leaf stage and doing well. Cotton planted just before the rains of early May has struggled, and some stands have been lost to excessive rains that totaled 10 inches in some areas, especially in north Louisiana.
Some fields emerged even with the rain-impacted soil, which is as much a testament to the excellent seed quality and seed treatments than to cotton’s ability to overcome stress. Relatively high temperatures have also helped provide the energy the seedlings needed to emerge through crusted soil and establish rapidly growing stands. More rain is forecast this week, so it will be a few days before field conditions improve substantially and allow planting to continue.
Meanwhile, some fields are showing weed infestations that will require quick action to bring under control, to avoid serious problems that could limit yields. Since essentially all cotton fields are planted with RR, RF or LL varieties, numerous weed control options are available for over-the-top applications of glyphosate or glufosinate as well as several selective grass herbicides for grass control. Caution should be used with the RR varieties such as DP 555 not to apply glyphosate after the four-leaf stage as this will cause some damage to plants that could result in yield reductions.
We begin this planting season under very wet conditions. As I submit this, we have only 26 percent of our cotton planted which is 11 days behind our normal average of 62 percent. Even more problematic is that our soils are very wet with our area soil moisture supply rated as 14 percent adequate and 86 percent surplus. Additional rainfall is projected through our prime planting season, but hopefully we will be dry enough to finish planting.
Producers have a greater capacity to plant or replant in shorter periods of time due to the use of wider planting swaths. Many of the conservation or no-till fields are ready to plant. The good news is that although our latest date of planting study shows that our ideal planting time is early May, we can have good yields in some years even when planted much later. I think that the reason we have had decent yields when planted late is that we are consistently able to harvest a “top crop” since the boll weevil has been eliminated as a key pest.
Speaking of the boll weevil, the assessment for our Missouri producers this year will be only $2.50 per acre. This is phenomenal. Our program was able to reduce costs because it was debt-free and has spaced traps at wider intervals. Our fate is tied to our climatic conditions and our ability to get the crop harvested. If we have the heat units, we could do all right.
As the cotton crop develops during June, a couple of important things for producers to consider are plant growth regulator decisions and post-directed herbicide options. Plant growth regulator strategies have been relatively straightforward with the widespread planting of one aggressively growing variety in Georgia. Hopefully, most producers have begun to experiment with other varieties and should closely monitor growth before making mepiquat applications. These varieties may respond differently to the current strategies implemented over the past few years.
With respect to weed management, producers have actively adopted the idea of adding pre-emergent residual herbicides into their programs. This herbicide application is likely one of the most important for control of Palmer amaranth. As decisions about post-emergence directed or layby herbicides are made, it’s necessary to remember that residual herbicides should be included in these applications as well.
For producers with glyphosate-resistant Palmer amaranth, the use of a residual herbicide will likely help provide season-long control. For those with susceptible weeds, the use of residual herbicides will help reduce selection pressure for resistance.
Much-above-normal rainfall in April and May has many Alabama farmers concerned about how much preplant nitrogen (N) fertilizer is remaining in their soil. Leaching of the N fertilizer out of the root zone is possible on most of the sandy soils across the state. On Alabama’s heavier soils of the Tennessee Valley and Black Belt, saturated and flooded soils often lead to large N fertilizer losses due to denitrification. Denitrification occurs because water-saturated soils are low in oxygen, and nitrate-N is converted to nitrogen gas and lost to the atmosphere. A study on a Black Belt soil in Alabama revealed that three days of flooding can lead to almost complete loss of preplant nitrogen fertilizer on these heavy clay soils.
As Alabama farmers begin planning side-dress N fertilizer applications, they will need to factor in possible preplant N losses. Farmers will need to consider soil texture, rainfall amount and if areas of the fields were under water for extended periods. Generally, more rainfall will mean higher N losses and flooded soils for more than three to four days could mean loss of most preplant N fertilizer.
Most SJV cotton by mid-May looked like it was off to a good start, with relatively decent looking root systems and limited severe early season insect damage. Limits in available irrigation water remain a problem that will be in the background of many management decisions for cotton and other crops throughout the year in the San Joaquin Valley.
Several fields have been checked out already this year for Race 4 Fusarium. In order to keep this disease in check, this is the right time of year for a reminder to: (1) investigate areas where plants die off early season; (2) look for root vascular staining to try to differentiate between Fusarium and other fungal seedling diseases; (3) check with your PCA or University Farm Advisor if you want a plant/field evaluation; (4) plant cotton varieties identified as more resistant if you are in a known infested area; and (5) use map or GPS for weak areas where stand loss occurred so you can see if weak areas expand.
Most fields we have evaluated to date are growing and developing on a relatively normal time schedule. The path you choose in managing cotton from here on out in part depends on the amount of irrigation water you can access for the rest of the growing season. If water supplies are extremely tight, it can be important to strike a careful balance and avoid being too early or too late with those first and second irrigations.
With limited water, a productive scenario would be to try to maintain high early and mid-season fruit retention during a compressed, shorter fruiting cycle. The goals would be to keep the plant smaller and less vegetative, and wrap up the whole production cycle in a shorter time period.
Frequent rainfall in May has resulted in the bulk of the Arkansas cotton crop being planted much later than normal. The optimum window for planting cotton in Arkansas closed on May 20, with approximately 40 percent of cotton acres planted. Late planted cotton can still produce high yields; however, fields should be monitored closely for pests or situations that will delay the crop further.
The warm temperatures during planting have made for a perfect environment for germination and seedling development. The cotton that was planted late emerged quickly – within four days – and looks vigorous and healthy. Late spring rains have provided plenty of soil moisture coupled with sunshine and warm temperatures, which will help this crop catch up quickly.
Increased monitoring of cotton growth and early use of plant growth regulators may be necessary to prevent rank growth and keep the crop on time.
Cool temperatures, excessive moisture, hard, packing rains, wind and sand abrasion, hail and environmentally-induced diseases are among the hazards that impact germination, emergence and seedling survival in our region. The “right” decision to keep the stand or replant depends on the circumstances pertaining to each situation and may vary from field to field or even among areas in a given field.
In making replant decisions, critical assessments should be made of the following factors: the plant stand density remaining after damage, stand uniformity (presence of skips), condition of the surviving plants, the calendar date and the costs associated with replanting. When making replant decisions, the first rule is to not make the final judgment on the extent of crop damage too quickly, and it is usually best to delay the final stand evaluation until after the crop is exposed to two or three days of good growing conditions.
Plants subjected to long periods of adverse growing conditions are often afflicted with seedling diseases that infect roots, vascular system and leaves. During periods of cool, cloudy conditions, the crop may appear relatively normal but will deteriorate rapidly when the weather turns sunny and hot. Historical High Plains data indicate that the lower limits of acceptable population densities for irrigated fields are about 1.5 plants per foot.
Until this recent cool snap, we were having great weather for cotton growth. I had been thinking that if we have decent moisture that the crop should look really good by the time you read this in mid-June. Well, hopefully the cool weather will be out soon, and it will stay warm enough for cotton to thrive, and the crop will be squaring heavily in mid-to-late June. Remember that mepiquat applications affect future growth, not past growth.
This period from mid-June until early bloom (usually early July) is when the cotton may need some mepiquat to control growth until boll load takes over in mid-July. I would start looking at my cotton at the eight-to-10 node stage and determining if applications are needed.
Rain, Rain...And More Rain!
Alabama started the spring with a deluge of storms and rainfall followed by heavy rainfall through the early part of May. While the 2008 and early 2009 months have provided us with adequate rainfall, the droughts of previous years are still fresh on everyone’s mind.
For that reason, our producers have kept irrigation and water management in the forefront of their research needs and priorities. Auburn University researchers have worked for many years on irrigation timing and methods. The 2008 Cotton Research Report includes the latest information on sprinkler and sub-surface irrigation in our state at www.alabamacrops.com. You’ll also learn about crop scouting and precision ag. Log in and visit us!