Indiana: Herbicide – Pay Attention, Check DriftWatch

Every year we get several cases of herbicide drift from burndown applications on homeowner trees, shrubs, flowers, and vegetables. This year has been no exception for these kind of drift complaints. What has been troubling to us this year is that we have received three separate drift complaints on landscape or vegetable nurseries within the last week.

After spending a tremendous amount of time, resources, and effort on dicamba training over this past winter, it is a little disappointing to have multiple cases of drift onto specialty crops this spring. While dicamba has not been the culprit herbicide in these three cases, many of the same principles taught in training should apply to all herbicide applications, especially near high value crops.

These investigations are currently ongoing, but we wanted to share what we have learned based on the submitted samples. For each case, we looked at wind data from the nearest weather station located at nearest Purdue Agricultural Center.

The first case involved suspected drift onto a certified organic nursery that is listed on DriftWatch. Based on information we were provided, it appears saflufenacil (Sharpen) was applied 700 feet away during a day where average wind speeds ranged from 5 to 16 MPH, with wind gusts over 10 MPH for most of the day. There was also 2,4-D injury on tomatoes in their hoophouse from an unknown source.

The second case involved 2,4-D drift onto a 1 acre landscape nursery that is not on DriftWatch. Out of two potential application dates we were given, both had average wind speeds between 5 and 10 MPH with wind gusts over 10 MPH for most of the day.

The third case had moderate to severe 2,4-D injury on several vegetable crops in a nursery that is listed on DriftWatch. The injured plants were located inside hoophouses and planted in the field. The suspected application was made on May 8 and 2,4-D was not listed as a product in the tank. May 8 was a day with light and variable winds all day, with potential inversions in the morning and evening. It is interesting to note that May 7 and May 9 were very windy in this location. We are currently not sure where the 2,4-D in this case came from.

All of these cases are dealing with some 2,4-D injury on specialty crops. 2,4-D is widely used in burndown applications across the state as it is still an effective and cheap option to add to any tank-mix. We also usually see 2,4-D injury resulting from applications made in high winds every year in the rush to get fields sprayed.

While we expected to see drift cases again this year due to the delayed start to burndown applications and planting, seeing injury on three nurseries is not acceptable, especially given the fact that two are registered and located on DriftWatch. As these investigations are ongoing, we also cannot rule out volatility of 2,4-D as a potential source off target movement.

The important lessons we can learn from these cases are that we need to watch wind speed and wind direction for all herbicide applications, and that volatility of products remains a potential concern for herbicides moving from the desired target field. Unfortunately, these can be expensive lessons to learn if fault is determined in cases where injured nursery crops can be valued over $20,000 per acre.

Source URL: https://extension.entm.purdue.edu/newsletters/pestandcrop/article/reminder-to-pay-attention-to-surroundings-and-check-driftwatch/