Some areas of Alabama have been experiencing temperatures in the 30's this last week and forecasters say that more cold weather is to come. This is also the time to be applying burndown herbicides to prepare for planting corn, soybean, and cotton. This isn't something new for Alabama as we can often have temperatures in the 70's during the day and the 30's at night. A concern for many growers is how their burndown herbicides will work with near-freezing temperatures at night and cooler days.
The statement found on most postemergence herbicide labels is to apply when "weeds are actively growing". However, freezing or very cold temperatures don't kill the plant but it does take them time to recover. Herbicide performance after a frost will be reduced if applied after a frost. Watching the plants is the best way to determine if the plants have recovered and are ready to be treated with a burndown.
Any herbicide that translocates within the plant will be greatly slowed down during cool temperatures. An example of a herbicide that translocates is glyphosate. The general recommendation is to avoid applying glyphosate when night temperatures fall below 40°F. Herbicides such as dicamba and 2,4-D work better than others during this time of cooler temperatures. The herbicides used in burndowns that are light-activated such as Sharpen, atrazine, and Gramoxone will not be adversely affected by the cooler weather although they would work more consistently if night-time temperatures were warmer (in the 50's). This is because they interfere with photosynthesis and are affected by temperature and the amount of sunlight the day of application and the days following.
Herbicide applications are strongly affected by weather conditions including temperature. Herbicide labels will advise on the proper temperatures to apply in order to get a consistent kill of the target weeds. As the Sharpen label states, "Burndown activity may be slowed or reduced under cloudy and/or foggy or cooler weather conditions, or when weeds are growing in drought or other stress conditions". The "other" stress conditions can refer to low nighttime temperatures when the weeds are recovering. It is best to avoid any herbicide applications during times in which nighttime temperatures will be less than 40°F and daytime temperatures are less than 55°F. However, in Alabama we often have the low nighttime temperatures followed by higher daytime temperatures. You can expect to have slower activity and may not see as consistent control depending on the product you use. Sometimes increasing the herbicide rate or spray additives can enhance performance. Always read the label and stay within the label rates.
Joyce A. Tredaway
Crop, Soil, and Environmental Sciences, Auburn University
The EPA approved revised labels for Engenia, FeXapan, and XtendiMax on Friday, October 13th. They have aligned the labels to coincide with each other which will make it much easier. The biggest change is that now these products are Restricted Use Products (RUP). This means that only certified applicators, or those under their guidance, will be allowed to purchase and apply these products. Record keeping is required of all applications. The label will list the full requirements but applicators have 14 days to generate the records and the records must be kept for at least two years. The rainfree requirement is 24 hours between application and either a rainfall or irrigation. Only daytime applications, between sunrise and sunset, are permitted. Applications are not permitted when the conditions exists for a temperature inversion. The sprayer must be cleaned both before and after application. Cleanout procedures must be documented as part of the RUP (date and method, as a minimum). Maximum travel speed is 15 mph with a recommendation of 5 mph on field borders. All supplemental labels are now combined into the main label. The use of an approved buffering agent may be warrented if the water source or tank mix components will create an acidic spray solution less than a pH of 5. In addition, sensitive crop awareness as part of the RUP by documenting that the applicator, at a minimum, surveyed neighboring fields or consulted a sensitive crops registry.
Since Alabama had a 24c last year, some of the same regulations will apply in the new label that were implemented in our 24c label last year. These include that applicators must complete an auxin-specific training, wind speed may not exceed 10 mph with the range being 3-10 mph, and not applying the herbicide when the wind is blowing in the direction of sensitive crops or downwind of the crop.
Alabama may make restrictions in addition to the main federal label. Decisions on this will be made soon and information will be forthcoming.
Timely Information number 14 - qhwR.docx
Hurricane Irma came through Southeast Alabama during September 10th and September 11th, 2017. After the storm passed through it was obvious that the Cotton crop was to bear most of the damage from this storm. During the storm in Southeast Alabama, wind speeds ranged mostly from 30 to 35 miles per hour. However, I have heard of some reports of 50 to 65 mile per hour gusts being recorded. We are very fortunate that the cotton crop was not impacted any more than what it has been from Irma. However, the consensus from my observations and grower input is that the negative impact from Irma is a loss of around 50 to 100 dollars an acre. This is from cumulative impacts as described in the summary. Certainly this is damaging to our Cotton farmers, who exist on narrow margins to begin with.
irma impacts on cotton.pdf
Timely Information number 13.docx
Potassium is a Macronutrient, which means that the nutrient is needed by the plant in larger quantities. ie over 20 pounds per acre of the nutrient for plant production. Potassium (K) is an essential nutrient for normal plant growth and development, which plays a particularly important role in fiber development. Potassium deficiency results in decreased fiber quality and lowered yields. If K is limited during active fiber growth, there is a reduction in the turgor pressure of the fiber resulting in less cell elongation and shorter fibers at maturity. Anything which restricts root growth, such as disease, insect damage, nematodes, root pruning, poor drainage, soil acidity, or compaction, reduces nutrient uptake and may increase K deficiency. Information about recognizing K deficiency is described in the attachment.Potassium deficiency in cotton TI.pdf
to the vulnerability of Alabama to hurricanes and their potential to cause
widespread damage due to high winds and flooding, disaster preparedness is
essential for livestock operations. Advanced planning can help producers
minimize the loss of animal lives and the health problems associated with
disasters. Although help may be available from many sources following a
disaster, producers themselves are ultimately responsible for the welfare of
their animals and should prepare accordingly. At the end of the attached Timely Information Bulletin is a checklist for livestock producers to consider when preparing for a potential disaster such as a hurricane.
Timely Information - Disaster Preparation for Livestock Operations.pdf
This information sheet provides an overview of considerations for beef producers who may retain ownership or receive calves for a preconditioning phase prior to marketing.
Preconditioning Beef Calves.pdf
Warm-Season Baleage Research TI Sheet - Hargaden.pdf
Potomac Horse Fever (PHF) was originally identified in the late 1970's as a disease affecting horses in the eastern United States near the Potomac River. However, since then, the disease has been diagnosed in other locations in the United States and Canada, but never in Alabama until recently. This summer, PHF was diagnosed in Alabama horses that had not travelled to regions typically associated with PHF, indicating natural transmission of the disease in Alabama. Potomac Horse Fever is a potentially fatal disease for horses, but is curable if treated early. The attached Timely Information Bulletin contains additional information about PHF to help protect horses from this potentially deadly disease.
Timely Information - Potomac Horse Fever recently diagnosed in Alabama.pdf
This publication provides information on dicamba drift in row crops.
Information Sheet Provided by: Dr. Joyce Treadaway
Timely Information Engenia number 12 updated.pdf
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