Critical Organic Insecticides

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organic certificationAuburn University Extension entomologist Ayanava Majumdar says for organic growers, the use of organic insecticides can make or break a production system. “Organic insecticides are critical for organic producers; we shouldn’t forget about them,” Majumdar says.

Southeastern weather conditions are among the most unique in the nation, making pests a year-round issue. For starters, the southeast has heat, humidity and unpredictable rainfall patterns. Additionally, southeastern growers may see summer pests, such as the yellowmargined leaf beetle, during the winter season.

Conventional growers have an easier time controlling mass amounts of pests, while organic growers struggle mostly due to their lack of management options. Majumdar says this is why organic insecticides are so important.

Majumdar says there are a few different types of organic insecticides: physical desiccants, contact and stomach poisons and products with volatile action.

Physical Desiccants

According to Majumdar, kaolin clay and diatomaceous earth are good, natural physical desiccants that can be easily found for purchase. The insecticide can dry up the insect and kill it. Majumdar says the downside to physical desiccants is the fact that they do not last in rain. So, the product must be reapplied after rain events in order to provide full protection.

Contact and Stomach Poisons

Contact and stomach poisons can be used conventionally and organically.

For contact poisons to work correctly, they must be applied in a timely manner, when the target insect is the most active. The most common organic contact poisons include vegetable oils, horticultural oils and botanical insecticides.

Regarding stomach poisons, Majumdar recommends Bacillus thuringiensis (Bt), a commonly known stomach poison that is specific to caterpillars. When using Bt, Majumdar advises timely sprays on small caterpillars, and a thorough spray schedule until the pest population crashes.


Volatiles are products that contain strong smells such as garlic or cinnamon. These strong odors can mask the scent of the plant, which confuses the pests. However, a downside to the volatiles is the fact that they must be reapplied constantly since they do not last long on the plant. Volatiles can be made in-house, or can be bought commercially.

Alabama vegetable IPM slidechart

Majumdar suggests that whether a producer uses organic insecticides or not, it is still critical that growers scout their plants weekly or as often as possible.

For home or urban gardeners, the new Alabama vegetable IPM slide chart is now available. It includes both conventional and organic insecticides for nearly 20 different crops. For more information or to get a copy, email



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Dan Cooper

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