Fundamentals of Herbicide Drift in Vineyards

Bruce Bordelon Purdue University Department of Horticulture and Landscape Architecture Outline • Herbicide “drift” – Types of chemicals involved – Drift ranges • Effects of 2,4-D and dicamba on – Symptoms – Cultivar sensitivity – Vine growth stage differences • Responding to drift – Identifying source – Reporting – Social and legal issues • What can be done? Pesticide Drift

EPA definition: Pesticide spray drift is the movement of pesticide dust or droplets through the air at the time of application or soon after, to any site other than the area intended.

Indiana definition: (Indiana Pesticide Use Law) (1) "Drift" means the physical movement of a pesticide through the air at the time of application from the target site to a nontarget site. The term shall not mean the movement of a pesticide, at a time after the application has been made, by any of the following: (A) Erosion. (B) Volatility after deposition on the target site. (C) Windblown soil particles. Drift and Volatility

• EPA pesticide label language is difficult to enforce. • Federal (EPA) definition of “drift” does not include vapor movement. – Indiana Drift Rule prohibits drift “in sufficient quantity to cause damage”, so applicator is in violation if damage occurs, however cases are difficult to substantiate. • Range of drift – Most ”drift” is relatively short range (hundreds of feet max) – Data suggests dicamba will drift ½ mile • Drift vs volatility • Wind speed, droplet size = drift • Temperature, vapor pressure deficit = volatility • Temperature inversions = volatility What is herbicide drift and what causes it?

• Types of chemicals? Any product can drift • Volatile herbicides in the WSSA Group 4 most problematic – Synthetic auxins (phenoxy carboxylic acid, benzoic acid, pyridine carboxylic acid) • Volatile herbicides* are capable of drifting considerable distances as vapor during or after application, especially if temperature inversions exist. – *Ester formulations of 2,4-D and dimethylamine salts of dicamba are most volatile – Pyridines can be very volatile (Crossbow, etc) • Applicator can do everything correct but problems can still occur. Temperature inversion Background on Herbicide Resistant Crops

• Roundup Ready (RR) Agronomic Crops (Corn, soybean, cotton, sugar beet, canola, alfalfa, sorghum) – Grown on millions of acres in North America for over 20 years (since 1996) – Increased no-till practices – Reduced residual herbicide use • Glyphosate resistant weeds emerging as major threat to row crop production – 29 weeds worldwide are resistant, 17 in the US – 4 major weeds in the Midwest confirmed • Marestail, giant ragweed, waterhemp, Palmer amaranth – Others suspected

Marestail Palmer Amaranth Produces up to 1 million seeds per plant

Giant Ragweed Solution to Glyphosate Resistant Weeds?

• Return to use of soil applied pre-emergent herbicides and cultivation (good stewardship) • Stacked herbicide tolerance traits in crops – Resistance to glyphosate plus other contact herbicides – Bayer (formerly Monsanto) – Xtendimax: Glyphosate plus dicamba with “VaporGrip Technology” – Corteva (formerly Dow AgroSciences) – Enlist Weed Control System: Glyphosate plus 2,4-D choline Volatile Herbicides and Sensitive Crops

2,4-D and dicamba are volatile herbicides capable of drifting as vapor

Grapes, tomatoes, melons, etc. are very sensitive Dicamba use on soybeans is not a nationwide problem

Since 2017 the number of dicamba drift incidents have increased significantly in the major soybean producing states. Both New HT Crop Technologies • Strong stewardship program • Will recommend the use of pre emergent herbicides • Integrated approach • Restrictions on: – Nozzles and pressure – Wind speed – Temperature inversions – Buffer required – Special training – Cut off dates Dicamba labels are complicated and temporary

• EPA approved the labels for 2 years beginning in 2017. • They renewed the labels with several changes in 2019. • Labels expire in December 2020 and will have to be approved for future use. • Impact of Ninth Circuit of Appeals ruling on June 3, 2020 is unclear. Implications of millions of acres of crops being treated with 2,4-D and dicamba during the growing season?

Similar amounts of 2,4-D damage

A lot more dicamba damage Pasture, hay, turf, right of ways?

• Mid-late season applications to turf and right-of-ways* pose min risk • Applications to pasture and hay fields may be more problematic • Temperature inversions may be an issue in hilly terrain Factors Affecting Herbicide (2,4-D and Dicamba) Damage to Grapes • Time of year exposure occurs – Pre bloom vs post bloom/fruit set vs mid-late season • Dosage – Particle (droplet) drift vs vapor drift • Variety (Cultivar) – Range from very sensitive to tolerant – Differential response on foliage and fruit set My Indiana experience

• 2,4-D injury every year since 1992 • Dicamba injury off/on since 2004 but none recently • Never had an actual “drift” event • Damage occurs “early” season, usually by late May – Coincides with burndown in no-till (beans) and post emergent in corn – Grapes are very sensitive during the early stage of rapid growth prior to bloom – Later the row crop planting season, more likely to see damage and the worse the damage will be

2,4-D symptoms on grapes

Characteristic fan shaped leaf with parallel veins Symptoms usually occur on new growth only Damage is usually minor with vapor drift unless it occurs prior to bloom Damage can be severe if: • Highly sensitive cultivar • Exposure occurs prior to bloom • High concentration (particle) drift • Root uptake Severe damage from 2,4-D drift Twisting and epinasty of growth. Necrosis in severe cases Drift may also contain other herbicides such as glyphosate, metalochlor, atrazine, etc. Complete crop loss, 2-3 years for vines to fully recover Impact of 2,4-D exposure on clusters when exposure occurs prior to bloom

Significant reduction in berries per cluster, thus yield. Impact of 2,4-D Exposure on Clusters Impact on fruit set Effect on fruit set - Aromella Effect on fruit set - Seyval Effect on fruit set - Exposure after fruit set Shoot stunting and reduced leaf area persists full season.

Vines ability to ripen the crop?

Vine capacity for next year? Mid season exposure to 2,4-D Economic impact? On some varieties, exposure makes shoots grow long internodes, small leaves (rat tails). Cultivar sensitivity and differential response evident. Impact of 2,4-D Vapor on Shoots

On some varieties, exposure stops the growing point, which leads to excessive lateral shoot development and shading of fruit, leading to poor quality. Variety sensitivity and differential response evident

Impact on training young vines? Impact of repeated 2,4-D exposure

• Reduced vine vigor (stunted shoots, short internodes, small leaf size, small clusters) – Reduced vine size – Reduced yield potential • Delayed ripening Cultivar Sensitivity to 2,4-D

Rating Variety Slight Cayuga white, , DeChaunac, (s), , Steuben, Ventura, , Vidal Moderate Cabernet franc, , , Chardonnay, Concord, , , , Riesling Severe Aromella, Foch, La Crescent, La Crosse, ,

Ratings based on multiple years observation of naturally occurring “volatile drift” in research trials in Lafayette, IN Very Sensitive Cultivars Very Sensitive Cultivars Moderately Sensitive Cultivars Moderately Sensitive Cultivars Slightly Sensitive Cultivars Slightly Sensitive Cultivars Differential response- Noiret

Shoots not affected much Fruit set significantly reduced Effect on fruit set - Noiret July-August phenoxy exposure? Late season such as right-of-way apps Risk of Dicamba Drift

Applications during the summer months are more likely to be during times of high temperatures and inversions Dicamba damage

Unlike 2,4-D, entire vine (all growth) shows severe and complete damage, without obvious drift pattern Dicamba damage

Unlike 2,4-D, entire vine (all growth) shows severe and complete damage, without obvious drift pattern Dicamba symptoms Pre-bloom

Upward rolling of leaves Flowers fail to develop normally Failure of flowers to bloom Upward rolling of leaves Failure of flowers to bloom Dicamba damage

Plants very slow to recover from damage. Subsequent growth also shows symptoms. Dicamba damage

By mid-season plants still not recovering Dicamba damage Failed fruit development, significant yield reduction

Damaged Normal Untreated Control 1/100 standard rate 10 DAT Simulated Dicamba Drift Study 24 hours after treatment Foliar Response to Dicamba

Rating Variety Slight Brianna, Cayuga White, , DeChaunac, Frontenac gris, Noiret, NY 76.0848.03, St. Croix, Vignoles, Vidal Moderate Chardonnay, Chardonel, LaCrosse, LaCrescent, Frontenac, St. Vincent, Traminette, Vincent, Severe Aromella, Cabernet franc, Foch, GR-7, Marquette, Melody, Seyval, Steuben, Riesling, Ventura

Ratings based on foliar response to mid-May application (8-12 inch shoots) of 1/100th standard field rate to simulate over the top application to soybeans. Damage in this trial was far less than experienced in 2004 or 2007 from naturally occurring “volatile drift” and plants recovered partially. Response not necessarily correlated with sensitivity to 2,4-D. Fruit Set Response to Dicamba Rating Variety Slight Brianna, Frontenac gris, Melody, NY 76.848.03, Valvin (ns effect) muscat Moderate Aromella, Chambourcin, Steuben, Traminette (sign. effect P≤.05) Severe Cabernet franc, Cayuga White, Chardonnay, Chardonel, (sign. effect P<.0001) Corot noir, Foch, Frontenac, La Crescent, La Crosse, Marquette, Noiret, Norton, Riesling, Seyval, St. Vincent, Ventura, Vidal, Vignoles, Vincent

Ratings based on foliar response to early application (2-4 inch shoots) of 1/100th standard field rate to simulate burn down in no-till soybeans. 17 of 25 varieties showed significant reduction in fruit set in treated compared to control (Max 85%, ave 41%, min 12%) Vidal

85% reduction in berries/cluster Norton

76% reduction in berries/cluster Noiret

49% reduction in berries/cluster Responding to drift

• Identifying source – Drift from adjacent farm? Easy – Volatility from who knows where? Difficult • Filing a complaint – Official complaint to state agency? – File claim with applicator’s insurance company? – Social and legal issues of filing complaints • Collecting samples for analysis – Admissible in court? Chain of custody?

Herbicide-Drift Risk Management for Specialty Crops NCIPM Factsheets https://ipm-drift.cfaes.ohio-state.edu Filing a Complaint

• Most states have a pesticide regulatory division that investigates drift complaints. – Pennsylvania has an good web site https://www.agriculture.pa.gov/Plants_Land_Water/PlantIndustry/health- safety/pesticide-programs/Pages/default.aspx • Fines tend to be low and no compensation to victim – Liability claims become the responsibility of the claimant, not the regulatory agency. • Social aspect of filing a complaint against neighbor – Communication

Janzen Ag Law Concluding Thoughts

• Indiana law imposes liability on the parties that commit the wrongs, even if accidental • Document liability and damages • Make sure insurers get notice

What Indiana has done Since 2017, Indiana has seen an enormous increase in drift due to dicamba. OISC has spent over $4 Mil on dicamba drift complaints alone

1. Adopted the state “drift rule” 2. Dicamba 24c label: Cut off date (June 20) to reduce complaints by 50% 3. Two types of drift complaints: (online complaint form) a) Enforcement: Full investigation with residue samples, photos, Pesticide Incident Investigation, etc. b) Documentary only: no residue samples or application information collected 4. Enforcement policy adopted 5. Revised Civil Penalty law 2019-20 Enforcement Response Policy

Violation 1st 2nd 3rd Subsequent Civil Penalty + General Use Warning Civil Penalty Civil Penalty 6 Month License Pesticide Suspension Civil Penalty + Civil Penalty + Restricted Use 5 Year Civil Penalty Civil Penalty 6 Month License Pesticide Certification Suspension Revocation Civil Penalty + Civil Penalty + Civil Penalty + Documented 1 Year 5 Year Civil Penalty 6 Month License Human Exposure Certification Certification Suspension Revocation Revocation Communicate

• Driftwatch web-based communication • Now FieldWatchTM Inc • www.fieldwatch.com

“Herbicide Tolerant Crops Stewardship” http://web.extension.illinois.edu/psep/articulate/ Communicate Use in some states has become widespread.

Dicamba labels REQUIRE applicators to check Driftwatch prior to making and application. Resources • PPP-110 Options for Dealing with a Pesticide Drift Event https://ppp.purdue.edu/wp-content/uploads/2016/08/PPP-110.pdf • ID-453 2,4-D and Dicamba-tolerant Crops: Some Facts to Consider https://www.extension.purdue.edu/extmedia/ID/ID-453-W.pdf • ID-465 Midwest Fruit Pest Management Guide Table of grape cultivar sensitivity https://ag.purdue.edu/hla/Hort/Pages/sfg_sprayguide.aspx • Herbicide-Drift Risk Management for Specialty Crops – NCIPM Factsheets https://ipm-drift.cfaes.ohio-state.edu • Janzen Ag Law-https://www.aglaw.us Questions and Comments?