The Department of Nematology's weekly NEMA 250 seminar series is presented this week by:

Andreas Westphal, University of California, Riverside

Seminar Title: “Adopting nematode management in walnut to changing production conditions"

Seminar Summary: Despite current market challenges, walnut is an important high-value crop in California. More than 4,500 growers produce this crop on 350-400K acres of deep-rooting California soils. These plant growth-promoting conditions also favor soil-borne pathogens. Pratylenchus vulnus is estimated to infest 85% of the walnut acreage. Soil fumigation has mitigated the damage potential of these soil-dwelling culprits. At times of increasing regulation and cost increases of this method, alternative management strategies are paramount to secure the vitality and sustainability of this specialty crop. Development of nematode tolerant and resistant rootstocks is a tedious but worthwhile endeavor to reduce the damage potential on the crop. Concerted efforts of an interdisciplinary team have led to rootstock accessions with multiple highly valuable traits. Alternative pre- and postplant soil and plant treatment strategies need implementation. Three main techniques result from these soil treatment studies: (1) preplant applications of the biofumigant Dominus, (2) anaerobic soil disinfestation, and (3) combinations of preplant soil treatments with intensive postplant application programs. The potential and limitations of these techniques will be discussed in view of future pest management strategies when fostering the sustainability of walnut production.