Issue link: https://www.e-digitaleditions.com/i/1084285
Former Merced County farm advisor David Doll spearheaded this research up until last November, when he left his post with the Merced County Cooperative Extension to pursue career opportunities abroad. While Doll's departure leaves a hole for the almond industry, his findings changed many of the assumptions and practices in how to deal with soil pest issues and fumigation — and opened the door for continued discovery. Determining the problem "Prior to replanting, growers need to determine if fumigation is needed by identifying which problem is present," Doll said. "It is common for people to assume they must fumigate, but the need depends a lot on cropping history and problems experienced on the land in previous crops." Preplant soil problems can be divided into three categories: abiotic issues, such as soil compaction, salinity and chemical imbalances; parasitic nematodes, primarily root knot, lesion and ring nematodes; and diseases such as PRD, which is a fungal complex that reduces fine feeder roots. Each condition reduces tree vigor and first-year performance, and all have lingering effects on tree growth and yield. PRD is a nearly universal issue when replanting almonds, but severity will vary across soil types. Along with crop and pest history, a nematode analysis should be taken in the fall two-to- three years prior to tree removal to determine specific nematodes present and to select appropriate rootstocks. Take the time to do it right Doll emphasized the need to properly set up the orchard for a fumigation treatment to perform its best. "The more time growers spend cleaning and preparing the field, eliminating roots, ripping the soil to A 1-year-old unfumigated tree (in foreground) displays reduced vigor in comparison to a Telone-II fumigated tree (background). Doll Advances Industry Understanding of Soil Fumigation When regulatory pressure limited the use and availability of traditional soil fumigants over the last decade, the Almond Board of California (ABC) funded research into managing soilborne pests, such as nematodes and Prunus Replant Disease (PRD), in almonds. David Doll Former Farm Advisor Merced County Cooperative Extension A 2-year-old tree (left of shovel) that was fumigated with Telone-II shows improved vigor next to an unfumigated tree (at right). 16 ALMOND COMMUNITY