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Integrated Pest Management

Blackleg in canola.


Bee on a canola plant.


Feral Rye stand in Canola field.


Horned lark sitting on a rock.


Winter canola field experiments conducted in east-central Washington were destroyed and commercial fields were damaged over several years by large flocks of horned larks that ate the cotyledon leaves of pre-emerged and newly-emerged seedlings. Numerous control strategies were attempted in field experiments, including laying bird netting over the entire experiment, placing a lifesize predator decoy in a field experiment, blasting a loud propane-powered cannon, mixing garlic with canola seed before planting followed by spraying garlic water on the soil surface, and applying a nontoxic bitter-tasting bird repellent to the canola seed before planting. None of the attempted control methods were successful. Another control method was tried by an Adams County, WA farmer who had just lost 260 acres of irrigated spring canola seedlings to horned larks. After replanting spring canola, the farmer hired a commercial falconer. The falconer brought six Aplomado falcons to the site. These falcons were trained to follow a ground-controlled airplane that was modified to resemble the size and appearance of an Aplomado falcon. Operating with three falcons at a time, the falconer systematically flew the airplane, followed by three falcons, over the canola fields at a height of 200 feet or less. Horned larks would take flight when they saw the falcons but would return to feeding in the canola field when the falcons passed over. Nonetheless, the density of horned larks soon declined as evidenced by diminished flock size. After the first day using the falcons, horned larks in the two canola fields were generally feeding in groups of four or less. Although some bird damage occurred, the farmer was able to achieve a satisfactory spring canola stand from his second planting. These experiences raise several questions: (i) Why did horned larks become a persistent problem beginning in 2006 at a site where winter canola had been successfully established many times (with no known horned lark damage) in several preceding years? (ii) Horned larks are native over a wide geographic area, yet damage to canola seedlings by this bird was documented in only a relatively small (i.e., 9,000 square mile) area. What are the implications of horned lark depredation to canola throughout the US and Canada? (iii) Why are new cotyledon leaves of canola so appetizing to horned larks? (iv) Why do horned larks infest some canola fields but not others? (v) How can horned larks detect pre-emerged canola seedlings through a strong odor of garlic?