ARS | Publication request: Mycobiota on wild oat (Avena fatua L.) seed and their caryopsis decay potential

Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 19, 2010
Publication Date: February 11, 2011
Repository URL: http://hdl.handle.net/10113/48364
Citation: De Luna, L.Z., Kennedy, A.C., Hansen, J.C., Paulitz, T.C., Gallagher, R.S., Fuerst, E.P. 2011. Mycobiota on wild oat (Avena fatua L.) seed and their caryopsis decay potential. Plant Health Progress. doi:10.1094/PHP-2011-0210-01-RS.

Interpretive Summary: Wild oat is an annual grass weed that is troublesome in cereal crops throughout North America, Europe and Australia. Few herbicides are available for wild oat control, yet development of weed populations that are resistant to the most commonly used herbicides is widespread. Identifying pathogenic and deleterious microorganisms may lead to crop management strategies that promote weed seed decay and reduce seed longevity, such as altered cultural practices (tillage, rotations, or soil amendments) or by inoculation of soil with deleterious microorganisms. The objective of this study was to screen fungi found naturally on seed for their seed-decay potential. Fifteen percent of the seed microorganisms resulted in decay symptoms on wild oat seed. A seed decay rating scale was developed that ranged from 0 to 5. The procedures developed here can be used by scientists, technical personnel and agricultural industries to investigate the potential of seed and soil microorganisms to decay seed and development of weed biocontrol.

Technical Abstract: Wild oat is a serious weed in cereals that is difficult to control due to long-term survival in the weed seed bank. The mycobiota associated with dormant wild oat (Avena fatua L.) seeds buried for six months in a no-till wheat field were evaluated for their caryopsis decay potential. Over 800 fungal isolates were obtained. The most common species were from the genera Papulaspora or Fusarium. Seed decay potential was evaluated in wild oat caryopses (hull removed). Of the 118 representative isolates tested for caryopsis decay, only 15% were found to have caryopsis decay potential. One isolate of Fusarium avenaceum and three isolates of Fusarium culmorum completely decayed wild oat caryopses within two weeks. Papulaspora spp. did not decay or inhibit wild oat caryopses. Only a few isolates were susceptible to the antifungal activity from water or acetone extracts of wild oat hulls, suggesting that soluble chemicals from the hull play a minor role in resistance to decay. The four Fusarium isolates decayed seeds of wheat (Triticum aestivum L.), oat (Avena sativa L.), downy brome (Bromus tectorum L.) and barley (Hordeum vulgare L.), but were not successful in decaying lentil (Lens culinaris Medik), pea (Pisum sativum L.), and jointed goatgrass (Aegilops cylindrica Host). The procedures developed here can be used isolate and screen individual organisms to determine their potential for seed decay and weed biocontrol.