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Pesticides

Columbia Laboratories has over 130 years of combined analytical experience in residue analysis with a library of over 600 standards. We offer an extensive suite of individual and multi-residue profile screens that are applicable to food, vegetation, soil, and water. Our most comprehensive Multi-Residue Screen is the P2220. With over 420 analytes it covers most requirements for importing food commodities and plant materials into the U.S. We offer environmental screens specifically for soil or water.

Profiles (Multi-Residue Screens)

  • P2750 Herbicide Screen in vegetation or soil
  • P7000 National Organic Program Pesticide Profile
  • Organophosphate/organochlorine pesticide profiles (for soil or water also)

Recommendations for Commodity-specific profiles: potato, mint, apple/pear, strawberry, sweet potato/yam, onion, honey, hay, etc.

Specialized Individual Analysis

  • Glyphosate (Roundup)
  • Imidazolinone herbicides (the “Imi’s”: Arsenal, Pursuit, Raptor, Cadre, Scepter)
  • Sulfonylurea herbicides (the “SU’s”)
  • Dithiocarbamates (EBDC, Mancozeb, Thiram, Zineb, etc.)
  • Fumigants in soil, grains, nuts (methyl bromide, Telone, propylene oxide, etc.)
  • Chloramphenicol, streptomycin & oxytetracycline antibiotics in honey
  • Many others (please call us for information about specific pesticides)

Applications

Residue Levels in Food

Foods are routinely analyzed to determine if there are any detectable levels of pesticides. If any are found, they must be below the Maximum Residue Limit (MRL) set by the consuming country. The MRL’s for several countries can be found by following the links on the External Links page of this website. MRL’s have a large safety factor built in for human consumption.

Soil Herbicide Carry-Over

A herbicide could be used against weeds in one type of crop, without harming that crop, whereas other types of crops might suffer damage. Carry-over problems can occur during crop rotation if residues of a herbicide remain in the soil from the previous growing season. To estimate the total amount of a pesticide in a field from the ppm in a soil sample: Parts per million signifies how many parts of a given compound is found in one million parts of the soil being analyzed. Soil is generally considered to weigh about 2 million pounds per acre in the 6-inch surface layer. Therefore, 1 ppm of a pesticide in soil is equivalent to approximately 2 pounds of active ingredient per acre, assuming a uniform distribution. ppm (w/w basis) = mg/kg 10,000 ppm = 1%

Detection of Spray Drift

Spray drift is the spreading of a pesticide beyond the intended borders of the area being treated. Common causes are wind, too hot conditions resulting in volatilization, and, accidental over-spray. Spray drift can be detected and measured by fairly simple means if steps can be taken at the time of application. One easy method is to place a paper towel or coffee filter on the ground before or during spraying. Afterward, place the paper (using gloves) in a Ziplock bag and send to the lab to be analyzed. If unable to take a sample at the time of application, vegetation samples can usually be analyzed later. However, delay works against this method because all pesticides begin decomposing in the environment due to sunlight, moisture, temperature, absorption and dilution by plant tissues, etc. Many pesticides are detectable within two weeks of application, while others may be detectable several months later. In either case, a call to the lab to discuss details would likely be helpful.

Cross-Contamination of Spray Mixes

Failure to adequately clean the mixing or spraying equipment tank when changing from one pesticide to another can result in cross-contamination of a subsequent spray mix. This may have no apparent effect, or, may result in crop damage. Obviously the best way to detect this would be to save a small portion (e.g., one ounce) of every tank mix (especially when herbicides were previously used) until it is determined that there are no problems from the application. Determining the cause of damage at a later time is subject to the same environmental factors mentioned above. If it becomes apparent that vegetation or soil samples may need to be tested, take the samples as soon as possible and store them in the freezer. This prevents further breakdown of any residues which may still be present.

Anti-Sprout Compound Levels on Potatoes

Even under optimum storage conditions potatoes can only be kept so long before sprouting begins. Sprout inhibitors are used to extend the storage time through the Winter and Spring until a new crop is harvested. The level of inhibitor is monitored so that just enough is used to prevent sprouting without causing excessive residues. If this were not done, fresh whole potatoes would be unavailable for some portions of the year

Herbicide Damage Issues

The following websites may be helpful when diagnosing herbicide injury to plants:

  • Diagnosing Herbicide Injury on Garden and Landscape Plants – Purdue University ID-184
  • Documenting Suspected Herbicide Damage – North Dakota State U./ U. of Minnesota WC-751
  • Herbicide Injury Diagnostic Key – U. Wisconsin HIDK
  • Herbicide Injury – Forestry Images pictures
  • Herbicide Injury Information and Photographs -Texas A&M U. TWIG
  • Weed Killer Damage to Plants – Kemper Center for Home Gardening (Missouri Botanical Garden)

Please contact us to discuss special applications or to receive free quotes for pesticide analysis.

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