Temperature inversions form a kind of air layering or stratifying effect. It becomes visible when smoke or fog rises and then seems to abruptly hit an invisible ceiling. Credit Judy Biss
Farmers and ranchers must manage traditional business practices to be successful, but they also deal with the many challenges of ever changing weather. Rain, wind, and temperature are important and obvious aspects of weather that producers track on a daily basis, but there are other, not so obvious weather features that affect operational management as well. One of these is a phenomenon called “temperature inversions.”
What is a Temperature Inversion?
Most of the time, if you were to take the air temperature at measured intervals starting from the ground, moving straight up in to the air, the temperature would be warmer at ground level than it is at higher levels over your head. A temperature inversion is simply the reverse of this gradient – the temperature of air at ground level is cooler than the air above it. These inversions occur naturally and most often in the late evening to early morning hours when there is little to no wind. Temperature inversions form a kind of air layering or stratifying effect. If you have ever seen smoke rise and then seemingly, and abruptly, hit an invisible ceiling, you have probably witnessed a temperature inversion.
Why are Temperature inversions important?
Temperature inversions are important because the air layering effect they cause changes the anticipated dissipation of pesticide spray solutions used by agricultural producers. Inversions also affect the movement of smoke from prescribed fires used by land managers. Under a temperature inversion, spray solutions and smoke have the potential to move great distances offsite instead of dissipating and diluting under normal atmospheric conditions. To make a long story short, agricultural producers and land managers do not want their pesticide spray solutions or smoke to move offsite in such a way that could negatively affect non-targets areas. Minimizing pesticide drift is a critical and routine part of pesticide application procedures. There are a number of techniques pesticide applicators use to reduce pesticide drift. One of these techniques is being aware of atmospheric temperature inversions. This is especially important when using organo-auxin herbicides that have characteristics making them more volatile, and thus more affected by air currents. Additionally, in light of the new herbicide application rules for dicamba resistant cotton and soybean varieties, managing pesticide drift is a critical part of stewardship of these new herbicides.
Detecting and Managing Temperature Inversions
Properly managing pesticide drift and smoke from prescribed fire includes using a number of best management practices by trained applicators and managers. Being aware of temperature inversions is only one of the variables they incorporate into their management decisions every day. Some herbicide labels have sections dedicated to explaining the importance of not spraying in areas where temperature inversions exist, and list ways to detect the presence of an inversion. See for example, the herbicide Engenia® by BASF. This is one of the herbicides approved for use on the new dicamba resistant cotton and soybean varieties. Before herbicides approved for use on these new plant varieties can be used, the pesticide applicator must attend a specialized training on proper stewardship of these products.
The Engenia® Herbicide Resource Center provides a number of Technical Information Bulletins, one of which details Recognizing Temperature Inversions. Below is an excerpt from that bulletin.
How to Identify if an Inversion Exists:
- Measure air temperature at 6–12 inches above the soil and at 8–10 feet above the soil. An inversion exists if measured air temperature at 8–10 feet above the soil is higher than the measured air temperature at 6–12 inches above the soil. Be sure the instrument is shaded and not influenced by solar heating.
- Morning dew
- Morning fog (indicates that an inversion existed prior to fog formation)
- Smoke or dust hanging in the air or moving laterally
- Overnight cloud cover is 25% or less
- Inversions can begin forming three to four hours before sunset and can persist until one to two hours after sunrise
This 3 minute video from the University of Minnesota Extension, provides great information on temperature inversions and how to detect them.
For additional resources on the topic of Temperature Inversions and Pesticide Drift Management, please see the following publications:
Last year, the Environmental Protection Agency (EPA) registered new dicamba herbicide product formulations for making applications to dicamba tolerant cotton and soybean crops. As a result, many states were overwhelmed with drift complaints regarding sensitive crops. This led to the 2018 EPA announcement requiring that anyone who wishes to apply dicamba to dicamba tolerant crops MUST participate in an auxin herbicide training before making applications in 2018.
[warning]This training is required of anyone applying newer dicamba products registered for use on dicamba tolerant cotton and soybeans.[/warning]
Product examples include XtendiMax, Engenia, and FeXapan. Applicators using older dicamba formulations in other crops (corn, forages, small grains, sorghum, and turf) can still apply dicamba products without having this training but thoseproducts CANNOT be used on the dicamba tolerant crops. If you have questions regarding the use of these products or if you need the training, call your local Extension Office before making any applications.
On March 16, Extension Offices from across the state hosted an online two-hour dicamba training, which was broadcasted live from Gainesville. This training was overseen by the Florida Department of Agriculture and Consumer Services (FDACS), who determined that the CEU form received from completion of this training would serve as the official documentation of attendance. If applicators desire to use the form for CEUs towards renewal of their pesticide license, they are required to keep an additional copy in their possession as proof of completing the dicamba training.
The training was recorded live and made available to all participating Extension Offices (see below). If you plan to make dicamba applications to dicamba tolerant cotton or soybean, you MUST complete this training before making any applications. The training is not required before planting dicamba genetics, but without the training dicamba cannot be sprayed on the crop. If you plan to spray the crop with dicamba, or want the weed control option later in the season, the training is mandatory.
[important]The recorded training has been made available to all participating Extension Offices. Applicators are required to watch it at the Extension Office, where it can be proctored by an agent who is a certified CEU provider and can issue/sign the CEU form. There are no exceptions, you must watch the training at an Extension Office. In the Panhandle, participating Extension Offices with access to the training include: Calhoun, Escambia, Gadsden, Holmes, Jefferson, Okaloosa, Santa Rosa, Walton, and Washington Counties. Contact information for the different offices can be found using the following link: Florida County Extension Offices.[/important]
Ethan Carter, Regional Crop IPM Agent, and Zane Grabau, UF/IFAS Nematologist
Newly registered for Florida, AgLogic 15GG (gypsum formulation) is a granular nematicide available for use in Florida cotton and peanut. The active ingredient in this product is aldicarb, which you may remember was the active ingredient in Temik.
[warning]Producers who plan to utilize this product for the upcoming 2018 crop season are REQUIRED to obtain an aldicarb permit through FDACS PRIOR to any applications being made. A separate permit application is required for each field where aldicarb will be applied.[/warning]
The one page permit application for applying aldicarb in Florida can be downloaded here. Once filled out, the permit application needs to be submitted to Tamara James, FDACS by email or fax (850) 617-7895. The website for submitting applications on the existing Temik page is currently being updated, and will be functioning in the near future.
Aside from the aldicarb permit, producers will also need to be in possession of a restricted use pesticide license, and strictly follow the label instructions for this product. See label for mandatory minimum distances between the nearest well and aldicarb application, as these distances vary based on soil type and well casing.
[important]Grazing restrictions are also associated with this product. Peanut hay and vines cannot be fed to livestock following AgLogic application. [/important]
This granular product should be applied in-furrow at planting, and may be followed by a post-emergence application before peanut pegging or cotton squaring. The post-emergence application must be side-dressed in an open furrow, and immediately covered with soil. Maximum application rates are 7 lbs./acre at planting for both crops, 5 lbs./acre post-emergence for cotton, and 10 lbs./acre post-emergence for peanut.
Submission contact – Tamara James (email) or fax (850) 617-7895
UF/IFAS Photo by Tyler Jones.
It’s that time of year again, the Florida Turfgrass Association (FTGA) and UF/IFAS have teamed up to present The Great CEU Round-Up. Designed to allow pesticide license holders to earn up to six CEUs, this all day program will be streamed online to participating extension offices around the state.
|487 General Standards/Core
|482 General Standards/Core
|Limited Urban Fertilizer
|Limited Landscape Maintenance
|Limited Lawn & Ornamental
|Commercial Lawn & Ornamental
|Ag Row Crop
|Ag Tree Crop
|Aquatic Weed Control
|Demonstration & Research
|Natural Areas Weed Management
|Ornamental & Turf
|Regulatory Pest Control
Extension Offices Participating, in the Panhandle, Include:
9:00 Pesticides, Pollinators & Politics in Turf & Ornamentals
10:00 Integrating Biological Controls & Herbicides
11:00 When Upland Invasive Plant Control Meets Water
1:00 Pesticide Spill Management & Cleanup
2:00 Aquatic Weed Identification
3:00 Herbicide Injury from Off-Target Application
UF/IFAS Employees: $15 until 7/22/16, then increases to $22.50
Municipal Employees: $30 until 7/22/16, then increases to $45
Industry Professionals: $50 until 7/22/16, then increases to $75
Registration can be completed online through the FTGA website or by downloading and then mailing the form. A hard copy registration form can also be picked up at any participating extension office. Registration CANNOT be done via the phone. It is important to register early as the cost of registration increases after July 22nd to on-site pricing (see above).