CONTAMINATED SOIL AMENDMENTSCecil Tharp, Montana State

UniversityPesticide Education Program

Be aware of the various modes of pesticide movement into non-target areas: Read

Environmental and Precautionary Statements!

Be Aware of Drift Grazing Intervals Re-crop restrictions Pre-harvest intervals Cutting restrictions Composting restrictions

Non-target toxicity towards beneficial plants on the rise.

2009 – 2011: 104 plant samples through Schutter Diagnostic Laboratory (31 counties*) 81 (79%) samples: damage likely

compost/manure/clippings 23 (21%) samples: damage likely drift or treatment

under or near woody (ornamental) plants

Top 5 Counties

Ravalli – 18 reports (includes injury complaints associated with manure/compost point contamination), Gallatin -16, Lewis and Clark – 9, Sweet Grass and Teton – 5 each, Flathead, Lake, Musselshell – 4 each

Understanding your pesticides persistence

See the Mont-Guide titled: Minimizing Pesticide Contaminated soil around the Home and Garden: MSU Distribution (406-994-3273)

Understand Persistence The ability of a pesticide to remain present and

active in its original form for an extended period prior to breaking down. Based on a pesticides ½ life. Based on characteristics of soil

Aerobic or anaerobic Long persistence present at wrong sites

Pesticide Persistence in Soils under Ideal Conditions

Low Persistence (half-life <30 days)

Moderate Persistence (half-life 30-100 days)

High Persistence (half-life >100 days)

Aldicarb Aldrin Bromacil

Captan Atrazine Chlordane

Dalapon Carbaryl Lindane

Dicamba Carbofuran Paraquat

Malathion Chlorsulfuron Picloram

Methyl Parathion Endrin Trifluralin

Permethrin Fonofos

2,4-D Glyphosate

2,4,5-T Heptachlor

Acie C. Waldron, Pesticides and Groundwater Contamination, Ohio State University

Extension Bulletin 820, 1992 available at <http://ohioline.ag.ohio-state.edu/b820/index.html>.

Pesticides Persistence is Still Dependent on many other Factors

Microbial Action - Process by which chemicals are degraded by bacteria or fungi

Photodegradation: the breakdown of chemicals by sunlight

Chemical Degradation: Hydrolysis: The breakdown of chemicals with

water increases in soils with a high pH. If > 8.0 (highly alkaline) lower the pH for better results:

Use Buffercide, Bufferplus, Unifilm B, or Nutra Plus. Recommend water within a range of 4 – 7

Picloram breaks down slowly in all soils…Always Read Product Label

(picloram)

Many pesticides break down slowly under anaerobic conditions.

New Chemicals on the Horizon

355 complaints of damage or injury towards trees.

A new herbicide used to manage broadleaf weeds in turf is implicated.

Aminocyclopyrachlor is expected to have a registration for pasture and rangeland in 2015.

Aminocyclopyrachlor Damage – ‘Perspective’

Proper Diagnosis is Key

Many samples are not from pesticide damage.

Insect Damage Plant Pathogens Other abiotic plant stresses

Not any one pesticide can be blamed for all mis-use. Growth regulator herbicide damage is likely the

culprit for a majority of samples. Major culprits: aminopyralid, picloram, clopyralid,

fluroxypyr, aminoclyclopyrachlor We need to increase the number of investigations

which precisely confirm the exact chemistry.

Proper Diagnosis is Key

Get an idea if you have a problem Use the MSU Extension non-target toxicity

website. Use MSU Extension agents Send samples to MSU Schutter Diagnostics Conduct bioassays

Conducting a bioassay

Figure 2: Results of a bioassay with known concentrations of aminopyralid. Plants shown are at six weeks after planting. Note leaf curling on plant grown in 5ppb (parts per billion) aminopyralid and death of plants at higher levels.

Use the ‘Non-Target Toxicity around the Home and Garden Website’

A platform for delivering non-target toxicity information to the public and educators. www.pesticide.montana.edu then select ‘Non-

Target Toxicity Around the Home and Garden’.

MSU video’s available online

Part 1 http://www.youtube.com/watch?v=zDXXkeEbIXE

Part 2 http://www.youtube.com/watch?v=KCnajfbwsSY

Part 3 http://www.youtube.com/watch?v=Ai4V-1XyLn0

For more information:

Cecil TharpPesticide Education Program

Montana State UniversityPhone: (406)994-5067

Email: ctharp@montana.edu

PGR symptoms from manure, compost or grassclippings.