Spray Drift Affects Sensitive Crops

R. David MyersExtension Educatormyersrd@umd.edu

A Vineyard Coming to a Farm Near You!

Vineyard Floor Management

2,4-D damage to vine

Vineyard Team

Ramano Vineyard Establishment Year 2007

Alternative Crops &

Sustainable Practices

?

CMREC , Upper Marlboro

http://annearundel.umd.edu/files/VEGWKREthnicVeg2002.doc

Market Garden

Herbicide Drift Potential

All herbicides are subject to particle drift.

Vapor drift potential varies by each herbicide’s vapor potential.

Droplet size controls both types of drift.

Wind, temperature and humidity affects drift severity.

Herbicides with High Drift Damage Potential

High vapor potential herbicides.

Herbicides that are active at very low application rates.

Herbicides that are Plant Growth Regulators (PGR’s)

WSSA Group 4Growth Regulators

Synthetic Auxins

Phenoxys Benzoic Acids Pyridines

2,4-D (many trade names)

2,4-DB

MCPA

2,4-DP (diclorprop)

2,4,5-T (no longer marketed)

Dicamba (Banvel, Clarity, Distinct, Vanquish, Status, many others)

Picloram (Tordon Grazon P&D)

Triclopyr (Garlon, Remedy)

Clopyralid (Stinger, Transline, Hornet)

Aminopyralid (Milestone, Forefront)

Herbicide Vapor Pressure mmHg @25○C (77○F)

EPTCVernam (vernolate)

Command (clomazone)

Treflan (triflualin)

Callisto (mesotrione)

Dual (metalachlor)

Prowl (pendimethalin)

Banvel (dicamba)

DCPAStinger (clopyralid)

Roundup (glyphosate)

Atrazine

2,4-D AmineClassic (chlorimuron)

Gramoxone (paraquat)

3.4X10-2 (.034)

1.0X10-2 (.010)1.4X10-4 (00014) incorporation breaking point

1.1X10-4 (00010) incorporate due to UV decomposition

4.3X10-5 (000043)

3.1X10-5 (000031)

9.4X10-6 (0000094)

9.2X10-6 (0000092)

2.7X10-6 (0000027)

1.3X10-6 (0000013)

3.0X10-7 (00000030)

2.9X10-7 (00000029)

1.4X10-7 (00000014)

4.0X10-12 (0000000000040)TLTL (Too Low to List)

Vapor pressure of selected herbicides arranged according to decreasing vapor pressure.

Note: Spray particles under 50 microns in diameter may remain suspended in the air indefinitely or until they evaporate.

In relatively dry, warm air (e.g., 30 percent relative humidity and 78°F), a 100-micron droplet quickly loses water by evaporation and becomes less than half its original diameter (one-eighth of its original volume) while falling only 2.5 feet.

By comparison, in relatively moist air (e.g., 70 percent relative humidity and 78°F), a 100-micron particle will fall 5 feet and hit the ground before evaporating to half its original diameter.

Small droplets become

smaller very quickly

Spray Drift Affects Sensitive Crops

R. David MyersExtension Educatormyersrd@umd.edu

AnyQuestions?