Cotton acreage is the smallest in many years across the Belt. However, timely defoliation and harvest are still important since weather is always unpredictable and can result in decreased yield and quality with one major weather event. Defoliation should begin when 60 percent of the bolls are open. Continue to defoliate fields if they can be picked within two weeks of defoliation.
If longer periods are anticipated between defoliation and picking, delay defoliation to prevent regrowth and staining of lint during picking operations. It is desirable to have less than five percent immature bolls that can be sliced through at the time of defoliation. In many cases, 75 to 80 percent of the bolls will be open before harvestable green bolls are mature at the top of the plant. These top bolls lead to little in way of yield and risk much for total yield and quality waiting until this stage matures.
Most defoliants do a very good job of leaf removal when temperatures are warm. However, weeds like morningglory can cause problems in certain situations. There are a few materials such as Aim and ET that are very effective in dessicating this weed.
There is some concern with leaf sticking with these types of materials, but that occurs mostly with young actively growing leaves and is less likely to occur with mature cotton leaves. Timeliness in defoliation and picking is a key factor for top yields and quality.
The Louisiana cotton crop made a good recovery from the June/July dry spell with the exception of about 10 to 15 percent of acreage that was either on very droughty soils or missed virtually all the rains. These particular fields are at 50 percent open bolls or greater (as of Aug. 14) with less than one bale per acre yield potential. The remaining acreage is mostly in good-to-excellent condition and well past cutout with many fields showing some open bolls.
A small percentage of very late-planted cotton will complete boll set the week of Aug. 17. In Louisiana, bolls set as late as Aug. 15 have enough heat units to mature, but reduction in sunlight quantity in September will extend the time from boll set to boll maturity, making it difficult for these bolls to reach harvestable maturity. Only a small percentage of the fields need any additional rainfall.
It would be preferable to have little rainfall during the next few weeks to minimize boll rot potential. Meanwhile, producers are facing some difficult management decisions for the remainder of August and early September. Because of the type of season we have had in Louisiana in 2009, many fields will have nutrients and water to continue growth after cutout, especially the drought-stressed fields.
Stressed fields are essentially fully mature but have several nodes of new top growth with blooms and even small bolls present. Individual plants have three to four open bolls, which equals a yield of 300 to 400 pounds per acre. These fields should probably be defoliated now, if not already done, and the crop harvested. Harvest delay to attempt to mature a top crop will likely result in yield and quality losses. We also have had an extended fruiting period in 2009, which means many fields have open bolls on the bottom of plants but need another 20 days to fill out top bolls, which will make it difficult to time defoliation to maximize yield and quality.
Bolls on the bottom and middle of the plant contribute more to yield than top bolls, and this should be the primary consideration when timing defoliation. Fortunately, there are many excellent defoliation products for most field situations that will remove mature and immature leaves and then prevent new growth.
Three-way mixes that include thidiazuron and ethephon, along with a traditional phosphate-based product or one of the newer products, are usually recommended in Louisiana and will give excellent results, especially when used with this year’s (drought stressed) cotton that has high regrowth potential. Several products contain more than one ingredient, so it is necessary when combining products, to check labels to determine the specific active ingredients in each product.
The LSU AgCenter online Publication 2927 (www.lsuagcenter.com/cotton) provides information on application rates for most defoliation products, applied singly or in tank mixes.
Those of us involved with Missouri cotton production are pleasantly surprised with the turn of events during this growing season. We are at the last effective bloom date and overall things look good. We have gone from wet to dry to wet. The Missouri Crop Progress and Condition of Aug. 9 shows that we have 14 percent poor, 31 percent fair, 51 percent good and 4 percent excellent.
The Aug. 13 USDA Cotton and Wool Outlook is projecting a yield of 1,061 pounds per acre. Last year at this time they were projecting our yield at 963 pounds per acre, and we ended up with a new yield record of 1,106 pounds per acre.
The rainfall has certainly helped the non-irrigated cotton, and irrigators have been able to relax for the last several weeks. This is encouraging, but a lot can happen before we get the crop out of the field.
We also have not trapped a single boll weevil during this trapping season, which compares with 19 caught last year. Boll weevil eradication efforts in surrounding states have reduced the migration of weevils into Missouri. Producers are grateful for their “top crop,” courtesy of this program.
With a return of $5 per $1 spent on boll weevil eradication, producers are really blessed. This year, the fee for maintenance will be $2.50 per acre.
Again, the success of this year’s crop yield and quality is highly dependent on weather conditions during harvest. We are hoping for the best.
The 2009 crop year in the High Plains has been a bumpy ride for our producers. Early season drought resulted in a more than half a million acres of dryland loss in the region. Much of the surviving dryland acreage is late and came up after mid-June rainfall events and is very late. The irrigated acreage is in much better shape. However, pumping costs will erode profitability. Decent July and early August rainfall has helped in some areas.
Yields will be a function of the irrigation capacity and efficiency of the delivery system (furrow, LEPA pivot, subsurface drip).
Marginally irrigated fields had a relatively short bloom period. These fields will produce lower yields and mature quicker than those with higher water inputs. As of this writing, we have had a relatively low insect pressure year.
Over the last several years – for numerous reasons – High Plains cotton quality has significantly improved. Much of this can be attributed to somewhat longer growing seasons, improved varieties, better irrigation techniques, rapid adoption of harvest aid chemical usage and in some years dry harvest conditions. The main take-home lesson is that if we do have dry fall conditions, we can capture very high quality in terms of color and bark contamination.
As we continue a trend toward planting notable acreage of less storm-resistant varieties, producers should be aware that we have to take care of business at the end of the season. We are also beginning to see more spindle picker harvesters in the region.
Realize that we are not only attempting to capture quality, but we want to reduce the potential for pre-harvest losses due to “High Plains meteorological events” that can occur during the harvest period.
We have been annually updating the High Plains Cotton Harvest Aid Guide, and this year we have added more information concerning picker harvesting. The guide can be accessed at http://lubbock/tamu.edu. We will be providing the updated guide during September and October crop tours and harvest aid meetings. Numerous excellent harvest-aid products are now available. Keep in mind that there is more than one way to get the crop terminated. Focus on what works in your area for the least cost.
The 2009 cotton season is finally starting to wind down, but we have a ways to go. It appears that some of our crop will need a good September to finish it out. At the time of this writing, most areas of the state have received some much needed rainfall, and most cotton is well into bloom.
There have been some reports of Stemphylium and Cercospora leaf spot in Georgia. The incidence of these foliar diseases is generally due to insufficient potassium levels in leaf tissue because of low levels in the soil or decreased potassium movement in the plant during dry weather.
While applying final insecticide applications and preparing equipment for harvest, producers should start to monitor the crop for defoliation. Proper timing of defoliation is critical to insure we maintain optimum yield and fiber quality. There are several methods that can be employed to help schedule defoliation. One method involves counting open and unopened bolls. It’s generally safe to proceed with defoliation when the percentage of open bolls reaches 60 to 75 percent.
Another method involves counting the number of main-stem nodes separating the uppermost first position cracked boll and the uppermost boll that is to be harvested. Once nodes above the cracked boll reach four, it’s usually safe to proceed with defoliation.
By now, yield and fiber quality have in large part been set, but proper defoliation timing and timely harvest can help maintain what we’ve worked so hard all year to obtain.
Irrigation termination has been popular topic recently in Arkansas. Previous data suggests that irrigation can be terminated at 350, 450 and 550 heat units for northeast, central and southeast regions. However, fields should be checked individually before decisions are made.
Weather conditions in the spring have resulted in shallow root systems in many cotton fields. These fields will require supplemental irrigation longer than those fields with deep root systems. Be sure to carefully examine boll load and root systems before terminating irrigation at 350 heat units after cutout. Conditions at the end end of the season will be a determining factor in this crop. Pushing the crop in any region will be a gamble.
How To Manage The Crop
Good management of a cotton crop requires making timely, well-informed decisions and then promptly acting on those decisions. Observing crop conditions and knowing what you have in the field and the progression of that crop toward maturation is critical in making a properly timed defoliation decision.
Proper timing of defoliation can mean the difference between one application of a defoliant and multiple applications. Once the final irrigation has been applied, watch the crop and attempt to time your defoliant application at approximately 60 percent open boll or when you have three to five nodes of unopened harvestable bolls.
Good luck to everyone this harvest season.