Location: Plant Science ResearchTitle: Identifying new seed treatments for alfalfa
Submitted to: Forage Focus
Publication Type: Trade Journal
Publication Acceptance Date: 2/28/2019
Publication Date: 3/15/2019
Citation: Samac, D.A. 2019. Identifying new seed treatments for alfalfa. Forage Focus. 3:4-5.
Technical Abstract: Rapid and uniform seedling emergence is critical for obtaining a productive and persistent stand of alfalfa. However, in many locations, alfalfa seeds are planted into cold, wet soil conditions that are ideal for seed rot and damping off to occur. A complex of soil-borne microorganisms cause seed rot and damping-off of alfalfa seedlings. Since the 1980s, alfalfa seeds have been treated with Apron (metylaxyl) or more recently with ApronXL (mefanoxam) to protect the seeds and seedlings from organisms causing seed rot and damping off. However, many strains of the pathogens are not controlled by current seed treatments. Newer, more effective seed treatments have been labeled for use on soybean seeds to protect them from seed and seedling diseases but none of them had been tested previously for control of alfalfa pathogens. Of the eight fungicides tested, three showed good activity against Pythium, Phytophthora and Aphanomyces and one also had activity against the Fusarium strains tested, that are aggressive seed rot pathogens. Most diseases of alfalfa are managed using resistant varieties. Importantly, because seed treatments are short-lived, a resistant variety would have improved adult plant root health, which would increase crop productivity. Resistant plants were selected from three diverse germplasm sources in an agar plate assay, planted into soil, and intercrossed within each germplasm. Approximately half of the lines had higher levels of resistance with some lines producing highly resistant progeny (>50% resistant seeds). A standard test for Pythium seed rot and seedling damping off has been approved by the North American Alfalfa Improvement Conference, facilitating registration of varieties with this trait.