Marijuana Business Magazine July 2018

U sing unhealthy pesticides is bad business.That fact is compounded by the multiple alternatives available to marijuana cultivators to control pests and contaminants like mold and mildew. Here are five tips to keep pests and contaminants at bay. 1 Keep Your Plants Healthy As Ben Franklin noted: An ounce of prevention is worth a pound of cure. Toward that end, growers say plant health is the biggest key to keeping pests and predators out of your grow. “Plants have a strong immune system,” said Casey Rivero, head grower at Yerba Buena in Oregon. “The healthier the plant is, the more it’s getting its nutrients and will fight off problems.” Christopher Vaos, a cultivation consult- ant in Colorado, agrees that prevention through maintaining healthy plants is the best strategy. But he cautions that apply- ing excessive nutrients can induce the problems you’re trying to avoid. “My view is that almost all plant disease – especially fungal disease – is related to not just environment but plant nutrition,” he said.When plants store too much nitrogen and potassium in their leaves but don’t have sufficient trace ele- ments, they fail to efficiently metabolize nutrients like nitrogen and potassium. “From a nutritive point of view, these plants love potassium, but too-high potas- sium in plant tissue is directly correlated to fungal disease, especially when it’s associated with low boron and low man- ganese,”Vaos added. “Few growers pay attention to that.” 2 Take Steps to Promote ‘Biosecurity’ Allison Justice, director of cultivation at California- based OutCo, said prevention “starts with really high biosecurity.” That means: • Growers change their shoes and clothes to minimize the risk of contaminants from the outside being brought in. • After harvest, staff members should empty rooms of plants and clean all surfaces with a disinfectant approved by the Organic Materi- als Review Institute (OMRI) that combines parasitic acid and hydro- gen peroxide. • Staffers should also replace filters in HVAC equipment after harvest, because they can harbor fungal spores and even insects. Rivero, for his part, dismisses precau- tions like Tyvek clean room garments and instead achieves biosecurity through beneficial bacteria and fungi. “If you have an abundance of beneficial bacteria, it’s harder for something from the outside to come in and destroy it,”Rivero said. 3 KnowYour Plants’ Characteristics Different plants have dif- ferent resistances to pests and contamination, so it’s good to learn the strengths and weaknesses of the cultivars in your grow. For example, according to PESTS & CONTAMINANTS Bug Off Five ways to keep critters and contaminants under control without resorting to dangerous pesticides SUSTAINABLE CULTIVATION 72 • Marijuana Business Magazine • July 2018