Lisa Munniksma
July 1, 2015

Some consumers think that if food carries the “organic” label, it has never been touched by anything that’s bad for them. The farmers who produce food according to the USDA National Organic Program standards know that’s not necessarily the truth. Under NOP rules, certain organic chemicals of mineral and botanical origin are permitted for use in food production, and some of them have hefty impacts on people and the environment. Before you head into your garden with a backpack sprayer loaded with an organic chemical, understand these precautions.

Identify Your Enemy

“Know what your pest is to start with so you’re not assuming something is damaging your garden when it’s not,” says Heather Darby, PhD, extension associate professor and agronomy specialist with the University of Vermont.

When you positively identify the problem, find the best method for treating it. For an insect pest, for example, go to integrated pest management before an issue progresses past a tipping point. Darby suggests reaching for floating row covers, insect netting and traps, too.

“Usually, chemicals are sort of the last resort in the insect- or pest-management plan,” she says. “It shouldn’t be your first, go-to control. [With other options exhausted,] choose a chemical that’s going to work the best to control that pest and have the least impact on other pests.”

The unfortunate case of many organic chemicals is that they’re broad-spectrum, meaning they don’t target just one family of pests but a wide range of bugs, including the beneficial bugs that you want to keep around. It’s possible that spraying organic-approved pesticides can do more harm than good.

Follow The Label

“Reading the label and understanding how to properly use the chemical is essential, and it’s also the law,” Darby says.

Agricultural-chemical labels are straightforward in their instructions. These will include:

  • Distance from a water source.
    Organic-approved chemicals can be toxic to aquatic plant, animal and insect life.
  • Protective-clothing requirements.
    Even organic chemicals can be irritating to the skin, eyes and respiratory system. Long pants, long-sleeved shirts and closed-toe shoes are the norm. Gloves and eye protection could be on the label, too.
  • Time of day to apply.
    Darby says a label might require that you wait until evening, when pollinators are less active, to apply certain pesticides.
  • Weather to apply.
    For example, a copper sulfate/calcium hydroxide bactericide/fungicide is an organic-approved treatment that can’t be applied when it’s too hot—above 85 degrees F, according to Purdue Extension—because it can cause plant leaves to drop.
  • Application rate and frequency.
    Pay special attention here: More is definitely not better! Purdue Extension points out that if an organic-approved chemical application doesn’t achieve your desired result, it’s probably because you don’t have the best spray for the job, you’ve improperly diagnosed your problem or you’ve applied the chemical incorrectly. Spraying more than the labeled application rate will waste your money and endanger you, the environment and your garden. An organic chemical will likely break down in the environment faster than a synthetic chemical, so you might have to apply more often to effective. The sprayer calibration section is an important read, too, as the proper spray density will prevent drift of the chemical onto unintended targets.
  • Chemical interactions.
    Some organic chemicals can negatively react with others, posing a threat to your, your plants’ and the environment’s health. For example, Purdue Extension cautions against using sulfur—an organic fungicide—in an area where you’ve used an oil-based spray in the last month because the combination is toxic to plants.
  • Proper disposal and storage of the chemical and container.
    Do not even think about reusing the container after it’s empty!
  • The re-entry period.
    Particularly for substances that can be irritating to the skin or respiratory system, the amount of time you need to steer clear of the treated field is real. Likewise, this section will tell you how long you have to wait before you can harvest and eat the treated produce.

With this information and more clearly stated on the label, you are legally responsible for following the rules. Darby says some state departments of pesticide enforcement are checking up on Certified Organic small-scale farms to be sure these laws are being followed. Agents might knock on your door and ask to see where agricultural chemicals are stored and where protective clothing can be found.

If you’re considering using an organic-approved herbicide or pesticide on your farm or in your garden, know your options and act with care. Organic pesticides and herbicides are still chemicals, after all.



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