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Disease



Time Orchard Mowing Right to Reduce Dust and Potential Disease


Reducing dust in almond orchards for mite control has been a common practice. Roads are watered, graveled or chemically treated to reduce dust. Decreasing vehicle speed is also recommended to minimize orchard dust. But mowing may be another culprit to kicking up dust in orchards, and at certain times of the year, may contribute to increased disease.   Mites and Dust Control Mowing, or any type of cultural activity requiring equipment within the orchard, will generate dust, according to Wes Asai, an almond grower and owner of Wes Asai Pomology Consulting in Turlock, Calif. “It’s that repetitive, heavy dust...

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Managing Hull Rot is No Easy Matter


With proper fungicide applications, regulated deficit irrigation and adherence to a nitrogen management plan, a grower should be able to manage hull rot in almonds. But even then, it is no sure bet. And the consequences of letting this disease get away can be severe. Left to its own devices, hull rot can inflict long- and short-term damage on almond orchards. It can reduce the bearing surface of trees by killing infected spurs and attached shoots and provide an overwintering host for navel orangeworm through infected sticktights that are not removed after harvest. For years, researchers focused their efforts to...

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Ganoderma Butt Rot: New Fungal Species Fells Young Trees


Until 2016, when UC Davis plant pathologists David Rizzo and Andrew “Bob” Johnson identified a species of the Ganoderma fungus previously unreported in the state, butt rot in almonds was considered a problem of older orchards. Since then, the newcomer, Ganoderma adspersum, has been found infecting orchards as young as four years old and has been responsible for a number of growers removing younger orchards because of extensive tree loss. So far, G. adspersum infections have been confirmed in almond orchards from Madera County south to Kern County. Reports also are limited to trees planted on Nemaguard rootstock. More recently,...

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Spring Diseases Provide Challenge for Almond Growers


When it comes to managing diseases in almonds, watching the weather can be as important as watching your crop. Especially in the spring, when diseases like brown rot blossom blight, jacket rot, anthracnose and bacterial blast threaten crop health, it is often the weather that determines disease pressure. “Watching the forecast is critical when it comes to control for all spring diseases,” said Florent Trouillas, UCCE Assistant Extension Specialist in plant pathology. In a typical year, brown rot blossom blight, caused by the fungus Monilinia laxa, is the most prominent disease at bloom. It is an outlier of sorts in...

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Bacterial Blast in Almond


In the wet and cold spring of 2019, the disease bacterial blast blasted almond orchards from Butte to Fresno county, destroying shoots and dormant buds and exposing trees to canker infections. There was no treatment or preventative product allowed for this infection at the time. By the spring of 2020, a Section 18 emergency registration use in almonds was secured for a bactericide that proved effective against bacterial blast, but warmer and drier conditions limited the opportunities for the bacteria to attack trees. A renewal of the Section 18 registration for UPL’s Kasumin has been submitted to DPR and EPA...

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