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On July 15, 2017

As we continue to hear more and more cases of dicamba drift cases across the mid-South, it’s important to remember that drift happens close to home too. Extension Agronomists Annie Klodd and Dwight Ligenfelter report hearing last week we heard of several claims of alleged 2,4-D drift damage in commercial vineyards in Pennsylvania. The growers believe these likely came from 2,4-D applications on nearby field crops during spring burndowns, and some damage was reportedly severe enough to kill all or part of this year’s wine grape crop. Still, for field crop growers, 2,4-D remains an important option for managing problem weeds like marestail, especially in the face of herbicide resistance. Therefore, it is important to follow the label when applying 2,4-D to reduce drift potential to other sensitive crops grown throughout the state. This article outlines 2,4-D label guidelines and explains how and when applications are most likely to affect off-target crops. Extension Agronomist Bill Curran suggests applicators keep this in mind to prevent these issues from reoccurring next spring.

In addition to grapes, other 2,4-D-sensitive high value crops in Pennsylvania include sweet potatoes, tobacco, peppers, tomatoes, melons, squash, and brassicas. In vegetables, the product often becomes unmarketable once the plants show visual herbicide damage. Grapevines present an additional challenge as a woody perennial crop – herbicide damage weakens the permanent plant tissue, which can translate into decreased yield and poor grape quality for several years. According to Mike White, an Iowa State University viticulture specialist who has been responding to 2,4-D drift reports on vineyards for years, vines can be damaged by 2,4-D drift as soon as the plant leafs out in the spring. Therefore, 2,4-D drift has the largest effect on grapevines when it’s applied between April and May – by this point, leaves are present and grape clusters are forming. Since this coincides with an important time for 2,4-D burndown in field crops, care should be used when applying 2,4-D burndowns in fields near vineyards.

In the case that off-target drift is confirmed, monetary consequences to the applicator can be high due to the high per-acre value of many of these sensitive horticultural crops. Land owners whose fields experience drift are able to file complaints with the state department of agriculture, which then investigates the claim to determine the source.

Here are some points to consider when applying 2,4-D, to prevent drift to sensitive crops.

Timing and awareness of the situation are critical considerations. It is not always feasible to time applications in a way that avoids sensitive periods for off-target crops. However, it is useful to be aware of when nearby sensitive crops are most susceptible to damage, as well as when they are being planted.
Many vegetables are most susceptible during flowering, but they can be damaged any time after transplant or emergence. Tomato injury often occurs May-early June. With grapevines, drift injury can occur any time after their leaves emerge but is often the worst (and will cause the highest yield loss) from April-June. Drift later in the season will have less effect on this year’s crop, but can largely lower the plant’s ability to survive the winter.

For fields, adjacent or near to non-target crops, larger buffers decrease injury potential. While 200-300 foot buffers are typically adequate, the safe buffer distance depends on other factors like wind speed and direction, air temperature, and topography. If applying the new dicamba formulations, check the label for specific minimum buffer requirements. Most 2,4-D and dicamba drift cases originate within 1/8 mile. Use nozzles that increase droplet size, and use lower spray pressures. Larger droplets decrease the risk for drift. Low spray pressure also decreases the risk for drift.

Avoid spraying during temperature inversions. Inversions often occur in the evenings and are indicated by very calm wind speeds (under 2 mph) and warm temperatures. Inversions cause herbicide particles to hover in the air after application, then gradually move upward and drift onto neighboring areas. Do not spray 2,4-D or dicamba if wind speeds are under 2 mph or above 12 mph.

Avoid spraying during periods of several days of high temperatures. Off-target damage from volatilization may increase if temperatures are too high during application. The risk of volatilization is directly related to increases in air temperature, and most volatilization occurs within 2 days of application.

On a closely related topic, you may want to check out these two new videos just added to the PA Soybean Board YouTube channel. In a case example, Dr. Bill Curran discusses Diagnosis of Soybean Injury from Dicamba Drift and Xtend Soybean Use and Precautions at this link:
https://www.youtube.com/channel/UCbQciftvKJd-fAzkuEBWquw

To Be Aware Of The Corn And Soybean Crop Development
Corn and soybeans in some areas have had a rough start with cool temperatures, soil crusting and slugs. However, Extension Agronomist Greg Roth reports with recent warm temperatures and widespread rainfall, corn and soybean are taking advantage of the good conditions.
For corn, stand variability and later planting dates were a concern early and the effects will persist somewhat, but soil moisture availability and good crop development in July will trump most of that early crop stress. Over 80% of the corn in the state is rated good to excellent despite these early season stresses. Many areas have received above average rainfall and this poses some risk for N loss especially on poorly drained soils. I think on some of our well drained soils there is still good nitrogen availability despite the early precipitation. Those tracking N losses with computer modeling may be able to identify fields that might benefit from a late season N application. This is the time of year where we see potash deficiency cropping up in many fields and that is true again this year. Uptake rates are very high and some crop fields have variability in soil K that shows up during this period. Make a mental note and follow up with soil testing and nutrient applications this winter.
Soybeans seem to be a bit later in flower and slow to canopy here in central Pennsylvania but in other areas in the southern counties, growth has been very good if not excessive in some cases. Again over 80% of the soybeans are rated good to excellent in the state. I suspect top end soybean yields might be limited by the late canopy development but we still have plenty of opportunity for pod development in July and seed fill in August. Areas with flooding injury may not recover well and yields will be limited in those fields. Double crop soybeans are off to a good start in many areas with the precipitation following wheat harvest and that should bode well for their yield potential.
To Report Your Corn And Soybean Acres
Extension Educator Andrew Frankenfield reminds us the crop reporting deadlines are coming up soon. Since the traditional reporting deadline of July 15 is a Saturday this year you get an additional two days to get your crop reporting done with your local FSA Office. Monday, July 17 is the final reporting date for corn, soybeans, CRP and all other crops.
For a list of Pennsylvania Farm Service Agency County Offices visit https://offices.sc.egov.usda.gov/locator/app?state=pa&agency=fsa
Also, remember to report your crops to your crop insurance agent at the same time. Most FSA offices will send your 578 as an email to your crop insurance agent.
Quote Of The Week: “Do more than is required of you.” George S Patton