Illinois Pesticide Review
September / October 2015
In This Issue
WPS Updated Finally!
The WPS gives farm workers protections afforded to workers in other industries.
Nothing in Washington, D.C. moves very fast. Revisions in laws can take years to make. Hold meetings and conference calls to collect valuable input from agricultural industry stakeholders across the nation and the process takes even longer. But that's what the U.S. Environmental Protection Agency (EPA) did recently in updating the 1992 Agricultural Worker Protection Standard (WPS). Revision plans began in 2000 with a formal assessment. I participated in the process at three large stakeholder meetings and wrote about what was being discussed in past issues of this newsletter. I began to wonder if I would ever see the end, but at last it is here or at least near.
This update, announced in late September, increases protections for the nation's two million agricultural workers and their families and gives farmworkers health protections under the law similar to those already afforded to workers in other industries. According to the EPA, each year, between 1,800 and 3,000 potentially preventable pesticide exposure incidents are reported that lead to sick days, lost wages, and medical bills; however, with changes to the WPS the risk of injury or illness resulting from contact with pesticides on farms and in forests, nurseries and greenhouses can be reduced. It is believed there is widespread underreporting.
"President Obama has called closing gaps of opportunity a defining challenge of our time. Meeting that challenge means ensuring healthy work environments for all Americans, especially those in our nation's vulnerable communities," said EPA Administrator Gina McCarthy.
"We depend on farmworkers every day to help put the food we eat on America's dinner tables?and they deserve fair, equitable working standards with strong health and safety protections. With these updates we can protect workers, while at the same time preserve the strong traditions of our family farms and ensure the continued the growth of our agricultural economy."
"No one should ever have to risk their lives for their livelihoods, but far too many workers, especially those who work in agriculture, face conditions that challenge their health and safety every day," said U.S. Secretary of Labor Thomas E. Perez. "Workplace illness and injury contribute greatly to economic inequality, and can have a devastating impact on workers and their families. By promoting workplace safety, these provisions will enhance economic security for people struggling to make ends meet and keep more Americans on the job raising the crops that feed the world, and we are proud to support the EPA in this effort."
EPA's updates reflect extensive stakeholder involvement from federal and state partners and the agricultural community including farmworkers, farmers, and industry. These provisions will help ensure that farmworkers nationwide receive annual safety training; that children under the age of 18 are prohibited from handling pesticides; and that workers are aware of the protections they are afforded under today's action and have the tools needed to protect themselves and their families from pesticide exposure.
Additionally, EPA is making significant improvements to the training programs including limiting pesticide exposure to farmworker families. By better protecting our agricultural workers, the agency anticipates fewer pesticide exposure incidents among farmworkers and their family members. Fewer incidents means a healthier workforce and avoiding lost wages, medical bills, and absences from work and school.
These revisions will publish in the Federal Register within the next 60 days. For more information on the EPA's Worker Protection Standard: www2.epa.gov/pesticide-worker-safety/revisions-worker-protection-standard
To view the prepublication version of the document that EPA will submit to the Federal Register: http://www2.epa.gov/sites/production/files/2015-09/documents/agricultural_worker_protection_standard_revisions.pdf
Once the rule publishes, it will be approximately 14 months before a majority of the rule revisions will be effective. This will provide time for states and farmers to adjust to the new requirements. Training materials will be updated during this time. The official effective date will be announced after publication. It is anticipated that compliance with most of the new requirements will be required in mid-December 2016, while the requirement for annual training will begin mid-December 2017, assuming training materials are ready. The WPS How to Comply manual will be revised.
Major rule changes include:
- Annual mandatory training to inform farmworkers on the required protections afforded to them. Currently, training is only once every 5 years.
- Expanded training includes instructions to reduce take-home exposure from pesticides on work clothing and other safety topics.
- First-time ever minimum age requirement: Children under 18 are prohibited from handling pesticides.
- Expanded mandatory posting of no-entry signs for the most hazardous pesticides. The signs prohibit entry into pesticide-treated fields until residues decline to a safe level.
- New no-entry application-exclusion zones up to 100 feet surrounding pesticide application equipment will protect workers and others from exposure to pesticide overspray.
- Requirement to provide more than one way for farmworkers and their representatives to gain access to pesticide application information and safety data sheets -- centrally-posted, or by requesting records.
- Mandatory record-keeping to improve states' ability to follow up on pesticide violations and enforce compliance. Records of application-specific pesticide information, as well as farmworker training, must be kept for two years.
- Anti-retaliation provisions are comparable to Department of Labor's (DOL).
- Changes in personal protective equipment will be consistent with DOL's standards for ensuring respirators are effective, including fit test, medical evaluation and training.
- Specific amounts of water to be used for routine washing, emergency eye flushing and other decontamination, including eye wash systems for handlers at pesticide mixing/loading sites.
- Continue the exemption for farm owners and their immediate families with an expanded definition of immediate family.
This table summarizes key provisions in the EPA's current WPS regulation and the 2015 revisions:
Michelle Wiesbrook, adapted from an EPA news release dated 9/28/15; http://www2.epa.gov/pesticide-worker-safety/revisions-worker-protection-standard
Detention Ponds & West Nile Virus
Detention pond with emergent weeds.
Dry detention ponds are designed to contain excess water during rains and then drain out the water soon after. They are commonly used near housing developments and industrial buildings where building and parking areas replace rainfall absorptive soil areas with hard surfaces, causing high water runoff during rainfalls.
Ideally, dry detention ponds completely drain of water soon after rains and are carpeted with turfgrasses that are mowed on a regular basis. Commonly, siltation and other vegetation change the characteristics of dry detention ponds, reducing their draining after rains and allowing moist soil or standing water to remain.
These conditions inhibit normal mowing intervals. Emergent aquatic plants, such as common reed, Phragmites australis, and cattails, Typhia spp., are able to establish themselves in these habitats. These plants create conditions that tend to accumulate additional silt and debris, further reducing drainage.
West Nile Virus (WNV) is spread in Illinois primarily by two mosquito species. Culex restuans bites only birds and serves to vector WNV between birds. The northern house mosquito, Culex pipiens pipiens, bites both birds and mammals and vectors WNV between birds and mammals, including humans. These mosquitoes do not fly very far, typically flying a half mile or so from the stagnant water where they developed as larvae. In comparison, the very common eastern floodwater mosquito commonly flies 15 to 30 miles as an adult but does not vector WNV.
Research has shown that mowing common reed and cattails in detention basins increases the number of WNV carrying mosquitoes two-fold, about 200%. The Culex mosquitoes that vector WNV lay their eggs in stagnant water containing large amounts of rotting vegetation. They prefer the dark-colored, stinky water typically found in clogged gutters, tree holes, tin cans, old tires, and other pools of water containing decaying plant material such as mowed emergent aquatic weed debris in poorly draining detention basins.
An interesting twist is that these detention basins with common reed and cattails commonly contain primarily red-winged blackbirds, starlings, and purple grackles. These bird species are bitten by the Culex mosquito species carrying WNV, but they are poor reservoir hosts for WNV.
In other words, mosquitoes that subsequently bite these birds do not transmit WNV to mammals and other birds very well. American robins are excellent reservoir hosts of WNV and are common in landscapes, but they don't tend to get close enough to the detention basins to be bitten by the homebody Culex mosquitoes there carrying WNV.
The take-home message is that dry detention basins should be managed so that they drain soon after rains and do not contain standing water or damp soils. This allows the basin to support turfgrasses that can be maintained by mowing on a regular basis. The lack of proper basin management results in increased West Nile Virus carrying mosquitoes that are a threat to workers in the basin and somewhat to the people nearby.
Areas with poorly managed dry detention basins should be monitored to determine the population level of northern house mosquitoes. If the Illinois Department of Public Health has determined that WNV is common in mosquitoes in the area, timely insecticide applications may be necessary to protect nearby residents.
Much of the above is based on the research conducted in central Illinois and is to be published by the Ecological Society of America as, Mackay, Andrew J., Ephantus J. Muturi, Michael P. Ward, and Brian F. Allan. Cascade of ecological consequences for West Nile virus transmission when aquatic macrophytes invade stormwater habitats.
Phil Nixon (mailto:email@example.com)
Boom Height: Uniformity and Drift
The height of the spray boom during an application plays a critical role in the two major goals of any pesticide application: making an effective application that controls the targeted pest while at the same time mitigating the risk of off-target drift.
Boom height impacts the efficacy of the application by affecting the uniformity of the spray along the length of the boom. The effect on drift is related to exposure of the spray droplets to the wind. We will look at each of these factors separately in greater detail.
Many broadcast applications are made with some type of flat-fan nozzle, such as extended range, pre-orifice, or air induction. These nozzles create a fan-shaped spray pattern that has the heaviest concentration of spray in the center of the pattern, with the amount of spray tapering off to nothing at the edges. Figure 1 shows a spray pattern from an air induction type of flat-fan nozzle captured by a spray table – note the shape of the pattern.
A boom has flat-fan nozzles evenly spaced along its length to make a broadcast application. In order to make that application uniform, the edges of the spray patterns, where the amount of spray is less than in the center, must be overlapped so that they combine to make the total amount of spray applied uniform along the whole length of the boom. This combining of spray patterns is called overlap.
There are three factors that affect overlap. They are nozzle fan angle, nozzle spacing, and boom height. The fan angle of the nozzle determines the total width of the spray pattern, with wider fans creating wider spray patterns. 80-degree (figure 2) and 110-degree (figure 3) fan angles are the most commonly used flat-fan angles in agricultural applications, but there are wider and narrower fan angles available.
The wider the fan angle and spray pattern, the more overlap is created by the nozzle itself. Nozzle spacing is the distance between each nozzle on the boom. The closer the nozzles are spaced together the more the patterns overlap; moving nozzles farther apart reduces overlap.
The final component that determines overlap is the boom height. If the boom is raised, overlap increases because each pattern has more room to spread out. Lowering the boom reduces overlap. While both fan angle and nozzle spacing also determine overlap, it is typically boom height that is used to set and adjust overlap on a sprayer. This is because once nozzles have been selected and placed on the boom, using fan angle or nozzle spacing to adjust overlap is impractical.
If you determine you need to increase overlap, you could change all of your nozzles to a wider fan angle, decrease the nozzle spacing and add more nozzles to the boom, or increase boom height. Increasing the boom height is obviously the best choice.
Most flat-fan nozzles require about 50 percent pattern overlap to make a uniform application. As shown in figure 4, 50 percent overlap means that the length of area that is being overlapped; i.e. receiving spray from two nozzles, should be 50 percent of the nozzle spacing. This means for nozzles spaced 20 inches apart the length of the area of overlap should be 10 inches.
For applicators, the key to achieving the correct overlap is knowing the ideal boom height for the nozzle fan angle and nozzle spacing their sprayer is set up with. Table 1 gives the suggested minimum boom heights needed to achieve sufficient overlap for different fan angles and nozzle spacings for nozzles from one nozzle manufacturer.
Table 1. Minimum boom heights for different nozzle fan angles and spacings.
20 inch spacing
30 inch spacing
40 inch spacing
Table 1 highlights how nozzle fan angle, spacing, and boom height interact. For any given fan angle, using a wider nozzle spacing means the boom must be higher in order to achieve sufficient overlap. Using a wider fan angle or a narrower nozzle spacing both allow boom height to be lowered.
The second major way boom height affects an application is by its impact on drift mitigation. As boom height is increased, the distance the individual spray droplets must travel before they reach the target increases. This increase in distance increases the time in which they are exposed to the wind, allowing them to be blown longer distances downwind.
The impact of boom height on drift can be seen in figure 5, which summarizes the results of measurements taken in a wind tunnel where all environmental factors were controlled. The researchers, from the USDA-ARS facility in Wooster Ohio and the Ohio State University, created droplets of various sizes, released them from different heights, and measured how far downwind the droplets moved before they deposited.
Five different droplet sizes were tested. Droplets are measured by their diameter in microns; 1 micron is equal to one millionth of a meter. As a reference, the human hair is about 100 microns in diameter. Starting with the largest droplet tested, the 300-micron droplet has no downwind movement when the boom is between 0.5 and 1.5 feet.
At heights greater than 1.5 feet, there is very slight downwind movement. The 200-micron droplet behaves very similarly except it does move downwind slightly at a release height of 1.5 feet, and has a greater increase in drift distance as boom height increases. The 150 micron shows a similar trend but with greater drift distances.
The 100-micron droplet has a very sharp increase in downwind drift distance as boom height increases, and highlights the importance of keeping the boom as low as possible. While there are many nozzle types and adjuvants available that can dramatically reduce the percentage of spray volume being released in droplets less than 100 microns, there are still some droplets in that size class, and a low boom height can help reduce the likelihood these droplets can move off target.
The 50-micron droplet shows a drift pattern that at first appears to be perplexing and not what would be predicted. It shows a substantial increase in drift distance as the boom is raised from 0.5 to 1 foot, but at higher boom heights its drift distance remains fairly constant. The prediction would be that it would continue to have further increases in drift distance as the boom is raised, so why does this not occur? The answer lies in the solution used for the tests: water. With no nonvolatile component in the spray solution, the 50-micron droplets evaporate very quickly. After 0.5 feet in boom height, the 50-micron droplet cannot survive long enough to deposit. The final distance given is how far it traveled before it evaporated completely.
The ideal boom height is one that provides the correct amount of overlap for the nozzle fan angle and spacing used while at the same time mitigating the risk of drift as much as possible. Check with your nozzle manufacturer to find the ideal boom height needed to achieve the correct amount of overlap and then strive to maintain this boom height throughout the application. Doing so will help to ensure an accurate, uniform application, which mitigates the risk of off-target drift. A final thought is that using a wider fan angle and a narrower nozzle spacing allows you to lower the boom height.
Scott Bretthauer (mailto:firstname.lastname@example.org)