Fusarium Avenaceum: A Potential Tool to Combat Wild Oats in the Soil Weed Seedbank.

Long-term dormancy and decay resistance of weed seeds pose a challenge to long-term weed management efforts. Environmental impact, consumer concern, and herbicide resistance necessitate the development of effective alternatives to chemical weed management.  Depleting the weed seedbank in the soil is an important component of an integrated weed management approach. Given the extended persistence of weed seeds in soil, their relationships with soil microorganisms are an under-utilized resource when developing ecological weed management strategies. Understanding the mechanisms involved in the weed seed-soil microbe interaction is the foundational knowledge upon which an improved weed management program can be developed.  In addition to its widespread resistance to herbicides, the seed characteristics of wild oat (Avena fatua L.) contribute to its status as one of the ten worst global weeds of temperate regions.

When dormant seeds of wild oat were challenged in vitro with Fusarium avenaceum isolate ‘F.a.1’, biochemical and molecular seed defense responses were induced and seeds were decayed. However, the ability of this isolate to cause decay in a soil system has not been demonstrated. Therefore, we are exploring the potential of fungi to decay dormant wild oat seeds in soil. Our objectives were to 1) develop a robust and repeatable soil-based method for assessing seed decay following exposure to fungi, and 2) evaluate the effect of variable soil properties on seed decay.  Seed decay and seed viability were quantified. The abundance of the Fusarium isolate in soil and in the seeds was determined using RT-qPCR.  To assess the effects of soil properties on seed decay, wild oat was sown in a diversity of soils inoculated with Fusarium. Additional progress on this research will be presented.