Cecil Tharp, Montana State University Pesticide Education Program

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

 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

 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

 See the Mont-Guide titled: Minimizing Pesticide Contaminated soil around the Home and Garden: MSU Distribution ( )  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 days) High Persistence (half-life >100 days) AldicarbAldrinBromacil CaptanAtrazineChlordane DalaponCarbarylLindane DicambaCarbofuranParaquat MalathionChlorsulfuronPicloram Methyl ParathionEndrinTrifluralin PermethrinFonofos 2,4-DGlyphosate 2,4,5-THeptachlor Acie C. Waldron, Pesticides and Groundwater Contamination, Ohio State University Extension Bulletin 820, 1992 available at.

 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

Many pesticides break down slowly under anaerobic conditions.

 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 Aminocyclopyrachlor Damage – ‘Perspective’

 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.

 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

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.

 A platform for delivering non-target toxicity information to the public and educators.  then select ‘Non-Target Toxicity Around the Home and Garden’.

 Part 1 Part 1   Part 2 Part 2   Part 3 Part 3 

Cecil Tharp Pesticide Education Program Montana State University Phone: (406)