Author Archives: Luke Milliron

Emergency Use (Section 18) Approved for Almond Bacterial Blast Material

Bacterial blast (Pseudomonas syringe), although thankfully not a problem every year (hopefully including 2021), can be tremendously damaging to almond yields. For example, significant crop damage was reported in the Sacramento Valley in 2017 and 2018, and in the San Joaquin Valley in 2017 and 2019. These grower reports of past crop loss supported a Section 18 emergency request for the use of kasugamycin on almonds during bloom. Continue reading

Almond Leaf Scorch

Beginning in late June, several PCAs and growers reported trees in almond orchards in the Sacramento Valley with symptoms like those of almond leaf scorch (ALS), a disease caused by the bacterium Xylella fastidiosa. UC farm advisors and UC and USDA plant pathologists have begun a survey to confirm disease presence and improve understanding of the disease in the Sacramento Valley. Continue reading

Tree and Orchard Replanting Considerations in a Lean Price Year

When prices are lean walnut farming is tough business. Farm advisors are not economists or financial advisors. However, farm advisors can be useful in providing best practices for economically sustainable production. Two key economic decisions growers face are when to replant individual trees and when to remove and replant entire orchards. Continue reading

Managing Mold in Walnut

Growers and processors have reported elevated mold levels in harvested walnuts to farm advisors and Dr. Themis Michailides, UC Davis Plant Pathologist. Although all possible predisposing factors have not yet been investigated, conditions that compromise the integrity of the hull, such as walnut blight, sunburn or insect-damage can serve as an entry point for mold fungi. Continue reading

Update on Rootstocks for Prune Production – 2019

Two rootstock experiments in grower orchards were planted in Northern California in 2011. One site in Butte County and a second in Yuba County. The two sites are evaluating the performance of Improved French on 14 rootstocks planted in replicated randomized trials. We previously reported in this newsletter on the results from this trial in 2015 and 2017 issues. Here, updated results are given. Continue reading

Monterey and the Leafing Failure: What could be causing it?

Researchers have historically been unable to pin down a cause for leafing failure because it was a rare event, only being reported periodically in the last couple decades. The problem was noted periodically before 2000, but most recent reports were made by farm advisors of leafing failure symptoms in 2000, 2006, 2010, 2017, 2018, and 2020. Continue reading

Autumn 2018 Freeze Event a Year Later

An autumn freeze event in November 2018 caused widespread dieback in both young and mature walnut orchards in the Sacramento and northern San Joaquin Valleys. Following our initial diagnosis in April 2019 and our update on regrowth at the end of May 2019, we revisited several affected orchards at the end of the 2019 season, nearly a year after the freeze event. Continue reading

Emergency Registration Approved for Almond Bacterial Blast Material

Bacterial blast, although thankfully not a problem every year (hopefully including 2020), can be tremendously damaging to almond yields. Because Sacramento Valley almond growers were significantly impacted by bacterial blast in two of the last three years, crop loss data from Sacramento Valley counties supported a Section 18 emergency request for the use of Kasugamycin on almonds. Continue reading