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Bayer trying again with dicamba

Earlier this year, PAN celebrated when a federal court revoked the approval of dicamba, a notoriously volatile herbicide widely used on soybeans and cotton. After fighting for better regulation of this drift-prone and environmentally damaging pesticide since its approval in 2017, we were thrilled with this development but knew the fight wasn’t over.

The court revoked dicamba’s approval for over-the-top application where the herbicide is sprayed after the crop has emerged from the ground.  This is the most common application method for dicamba and it is also the most likely to volatilize and drift.  But we expected that Bayer would reapply for approval with a new label in an attempt to circumvent this ruling. And that’s exactly what happened.

According to EPA, the new label would, “allow application to dicamba-tolerant soybeans made before, during, or immediately after planting until emergence of the seedling, but no later than June 12 of each year.” And in the case of cotton, “would be allowed before, during, immediately after planting, or ‘over the top’ of the cotton plant, but no later than July 30 of each year.”

Over-the-top (OTT) spraying is used in combination with Bayer’s seeds which have been genetically modified to withstand dicamba’s systemic growth-inhibition. Dicamba is sprayed OTT when the crop is established to control weeds. This means that it is typically sprayed in late spring and early summer, when heat increases volatility. Bayer’s new label restricts use to certain timeframes, but this simply isn’t good enough.

Emily Marquez, Senior Scientist at PAN, wrote the following letter to EPA to explain why no over-the-top use of dicamba should be approved, and why restrictions on when dicamba is sprayed have historically done little to decrease drift damage.

PAN’s comments on Bayer’s new dicamba registration proposal

{These comments were submitted for this EPA file: EPA-HQ-OPP-2024-0154, Dicamba: New Use on Dicamba-Tolerant (DT) Cotton and Soybeans}

The following comments are submitted by Pesticide Action Network (PAN) North America. PAN works to replace the use of hazardous pesticides with ecologically sound and socially just alternatives. PAN North America is one of five regional centers worldwide and has over 90,000 members nationally.

EPA should deny this application for dicamba. Drift incidents of dicamba have caused substantial damage ever since conditional registrations were granted for over the top (OTT) use of dicamba formulations on dicamba tolerant (DT) seeds. Based on the data EPA has collected from on-the-ground sources, dicamba will continue to cause millions of dollars of damage to crops and harm the environment via off-target drift.

Dicamba drift incidents continue to occur in spite of additional restrictions

EPA collected and compiled 2021 data on off-target dicamba drift from multiple sources (Tindall et al. 2021). Dicamba drift incidents have occurred with legal applications done in compliance with additional restrictions. In addition, cutoff dates with dicamba impose difficulties on farmers and can be very difficult to adhere to. Based on various observations, such as planting dates of double cropped soybeans, it appears likely that cutoff dates were not adhered to in some states, and other states directly reported known violations of cutoff dates. When discussing increased enforcement, states have cited reduced budgets as an issue that prevents improved enforcement. These challenges, in addition to the knowledge that dicamba drift damage can occur even with applications that are in compliance with restrictions, provide additional evidence that EPA should not grant this application for use.

EPA acknowledges that a significant number of drift incidents are not reported, estimating that dicamba incidents were underreported by a factor of 25, with no evidence to suggest that this pattern has changed. EPA reported that dicamba damages have not improved from “previous years in the number, severity, or geographic extent of incidents (Tindall et al. 2021). With no apparent changes in the number of incidents occurring, EPA should not allow this use of dicamba. Dicamba volatility is still resulting in damage, in spite of so-called less volatile formulations, and therefore continued use of dicamba products can only exacerbate the problems caused by drift damage.

EPA noted that “restriction against OTT dicamba use in soybean would likely result” in reducing dicamba drift in states with high production of soybeans. EPA also noted that incidents could still occur. The prediction that restrictions will “likely” reduce drift incidents on soybeans is not supported by data. Data collected by EPA indicates that restrictions did not result in the hoped-for significant reductions in drift during the time period that those restrictions have been in place. Dicamba damage has been reported to occur at a landscape level even with compliant usage and has been reported to drift 1-2 miles, or 20 miles away, in SD and AR, respectively (Tindall et al. 2021).

Finally, with climate change causing increased drought and high temperatures across the country, the number and severity of dicamba damage incidents are highly likely to increase over time. Dicamba volatilization is known to greatly increase with temperature, especially at temperatures above 80-85°F, and dry conditions increase the severity of dicamba damage (Tindall et al. 2021). This provides yet another reason why EPA should deny this application.

Farmers planting non dicamba soybeans and sensitive crops are not protected from dicamba drift

Dicamba appears to be a very popular pesticide, but not for the farmers who aren’t planting DT crops. Growers have reported reluctance to report neighbors and growers’ social relationships have also suffered, due to divisions over seed choices and frustrations with drift incidents. Dicamba drift onto non-DT soybeans and other sensitive crops occur, with the majority of damage reported in 2021 occurring on non-DT soybeans (Tindall et al. 2021). Buffer zones cannot protect against dicamba volatilization, and this is supported by the information collected by EPA. Dicamba drift damage to sensitive crops costs farmers their livelihood and is an unacceptable consequence of widespread dicamba use.

The total extent of dicamba damage to sensitive crops, trees, and other non-crop plants is still unknown

With drift reported to be occurring up to 20 miles away, the extent of damage caused by dicamba would indeed be hard to assess. Off-target drift incidents have affected local plant life, and have drifted onto state parks and wildlife refuges. Reports on dicamba injury to non DT soybeans have been reported in at least 8 states, as well as damage to six large acreage crops and more than 10 specialty crops (Table 4, Tindall et al. 2021). EPA should deny this application based on the data that has already been collected.

Not all of the states reported the extent of the damage in terms of acreage or the number of calls received. EPA should ask states to improve data collection on drift by asking them to track the number of calls received, the estimated cost of drift damage, and data on acres damaged. These data would add important information regarding the costs in damages borne by non-users.

Dicamba resistance in weeds has increased

Dicamba-resistant Palmer amaranth has been confirmed in two states, with decreased sensitivity to dicamba in at least five states (Orlowski et al. 2020). Dicamba resistance has also been reported in waterhemp. EPA noted that as resistance spreads, the benefit of dicamba tolerant traits will decrease (Tindall et al. 2021). Continued and widespread dicamba use will only accelerate the development of resistance in weeds. The problem of herbicide resistance is known to occur with widespread herbicide use and is well supported by data.

EPA has more than enough data on the problems caused by dicamba drift and should deny this application. Thank you for the opportunity to comment.

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