Walnuts Archives - West Coast Nut

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Walnuts



Walnut Pest Management: Walnut Husk Fly & Pacific Flatheaded Borer


It seems that growers are always battling pests in order to protect their crops. While we looked into navel orangeworm and codling moth in the first part of this two-part series, this second part shines the light on walnut husk fly and the Pacific flatheaded borer. So just how concerned should a walnut grower be about these pests? They don’t require equal interest, as one is more of a concern than the other. Walnut Husk Fly About the size of a housefly, and far more colorful, the walnut husk fly has one generation per year, in which female flies lay eggs beneath the surface of the walnut husk. The first sign of infestation is a point-sized, stinglike mark on the husk. And while it might initially be an easy miss, the husk will eventually show black marks as the eggs hatch and the maggots feed and destroy it. After feeding,...

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Increasing Evidence of Pacific Flatheaded Borer Attack in Walnut Orchards in California


Background and Pest Status Flatheaded borer is a larval stage of one specialized group of beetles (Insect family-Buprestidae), which are glossy iridescent colors. The name ‘flatheaded’ comes from the enlarged and flattened shape just behind the head of the larval stage (Fig. 1) of the beetle (Fig. 2), and the flatheaded borer species that has become a major issue in walnuts is Pacific flatheaded borer (PFB), Chrysobothris mali, which is known to present in the western states such as Washington, Utah, Oregon, California. A similar type of borer species causing serious damage in various nurseries and other fruit and trees in the eastern part of the United States is called Appletree flatheaded borer, Chrysobothris femorata. Although Pacific flatheaded borer has been an occasional pest of young fruit and nut crops in the past, in recent two years, this borer has become a...

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FSMA Produce Safety Inspections: What to Expect


The Food Safety Modernization Act (FSMA) was passed in 2011 to help prevent foodborne illness outbreaks. Under the FSMA rules are the Preventive Controls Rule (PCR) which covers processors/handlers and the Produce Safety Rule (PSR) which covers farms. The PSR is being implemented in stages between 2019 and 2021 depending on farm size. In California, Food and Drug Administration (FDA) is contracting with the California Department of Food and Agriculture (CDFA) to conduct the on-farm inspections to verify FSMA compliance. CDFA has created the Produce Safety Program (PSP) to educate and assist growers in complying with PSR requirements. Impact on Walnut Growers All farms covered under the Produce Safety Rule must take several steps to comply with its requirements. Key steps include at least one farm representative complete an FDA-recognized Produce Safety Rule Grower Training Course. This training, in turn, will inform how to implement required Produce Safety Rule food...

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Walnut Pest Management: Navel Orangeworm and Codling Moth


There are a few pests that have reached what seems like celebrity status in the tree nut industry, with codling moth and navel orangeworm being household names for walnut growers. With research is continuing on how to best eliminate these pests, there are still methods and products that can help with the complications of infestation. Navel orangeworm and codling moth are featured here in this first part of a two-part series focusing on pests in walnut orchards. Navel Orangeworm Navel orangeworm has garnered a lot of attention, as growers and industry personnel continue to battle this pest. When mummy nuts are left on trees, the navel orangeworm identifies these as ideal places to lay eggs. Those eggs—which are a solid white when they are first laid, then turn pink, then reddish orange and overwinter as larvae. This moth starts emerging in April, and peaks in late-April to mid-May. The cycle...

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Preparing Walnut Trees for Winter


Fully dormant mature walnut trees can tolerate temperatures into the low 20’s or below, so long as trees are in full dormancy, according to University of California Cooperative Extension (UCCE) farm advisor, emeritus, Wilbur Reil. While it’s tempting to push young tree growth as long as possible in the fall, it’s also risky. Freezing temperatures can cause die back in young trees, sometimes almost to the roots. Freeze events can also severely damage trees in mid-winter if the soil is dry. Fully dormant walnut trees can withstand temperatures well below freezing, but young trees are more susceptible to damage. It can be particularly damaging for young trees when temperatures drop to 28 degrees F or below before they’ve experienced a few nights near 32 degrees F to become acclimated. Trees can be managed for cold hardiness by:

  • Stop nitrogen fertilizer applications after September first to avoid new...

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