Flaxseed Oil for Control of Peanut Rust and Its Disease Control Mechanism

Severity of peanut rust caused by Puccinia arachidis was reduced by 15 edible oils tested. Flaxseed oil was the best suppressing the disease completely. Peanut oil, wheat germ oil, brown rice oil, aloe oil, olive oil and corn germ oil also caused more than 75% reduction in disease incidence. Flaxseed oil reduced the rust to a negligible level in the greenhouse and was nearly as effective as the fungicide chlorothalonil in peanut field trials. The control of peanut rust by flaxseed oil did not result from activation of the host defence mechanisms. Flaxseed oil did not affect urediniospore germination, but reduced the germ tube length and completely suppressed appressorium formation which is essential for the pathogen to form an infection peg to pass through the stomatal aperture and infect the host tissue. Although the pathogen had penetrated, flaxseed oil still exerted some inhibitory effect against the growth of the pathogen. The advantages of using flaxseed oil to control peanut rust are that it is relatively inexpensive, easy to prepare, and friendly to the environment and human health.