• Isik Ozturk

Pelargonic acid: Is it a long-awaited safer alternative to synthetic chemical herbicides?

The agriculture industry and the society in general are looking for new alternatives to synthetic chemical herbicides for weed control. As such, the efforts to discover natural substances that can act as (bio)herbicides has increased exponentially during the last decade. Three natural products; pelargonic acid (PA), carvacrol and cinnamic aldehyde seemed to be ahead of others and are increasingly utilized. Science indicates PA as to most efficient of the three.

PA (CH3(CH2)7CO2H, n-nonanoic acid) is a saturated, nine-carbon fatty acid naturally occurring in numerous vegetables and fruits, including oranges, grape, apples, and potatoes. In 1992, the US Environmental Protection Agency had licensed for sale the first pesticide products containing ammonium nonanoate as ‘biochemical herbicide’ concluding that no risks to human health were to be expected from the use of ammonium salts of higher fatty acids. Following the first generation of natural herbicides based on PA as active ingredient, a number of new formulations have been developed and approved as herbicides against a wide spectrum of annual and perennial weed species.

PA acts exclusively by contact, attacking and destroying the cell membranes of the plant epidermis and causing rapid tissue dehydration. Above 15 °C, on a luminous day, drying action is extremely rapid. The treated plants begin to exhibit damage within 15–60 min of the application and begin to collapse within 1–3 h. In one of our recent trials, we have observed that herbicide action was fast, non-selective, and highly broad spectrum that led to large necrotic lesions on parts (or the whole) of the target plants. PA was the clear winner against the other herbicides tested.

Based on new research, and our own experience, PA could be the very alternative to synthetic herbicides.