Growing the Valley

Our concerns about how climate change will affect agriculture don’t just extend to crop performance; pest species will also be affected. In this week’s episode, Lynn Sosnoskie returns to talk about implications for weed management.

Episode transcript

Thank you to the Almond, Pistachio, Prune, and Walnut Boards of California for their kind donations. Thank you to Muriel Gordon for the music.

The views, thoughts, and opinions expressed are the speaker’s own and do not represent the views, thoughts, and opinions of the University of California. The material and information presented here is for general information purposes only.  The "University of California" name and all forms and abbreviations are the property of its owner and its use does not imply endorsement of or opposition to any specific organization, product, or service.

Almond production creates a lot of byproduct. While there are some alternative uses for almond hulls and shells, like livestock feed and bedding, there is still not enough demand to utilize all the biomass created every year. Some growers have been accepting almond hulls and shells from processors to help them get rid of these stockpiles, and using them as mulch in orchards. Ellie Andrews examined how using hulls and shells benefits almond orchards, including their potential as potassium fertilizer, and how they affect soil health.

The views, thoughts, and opinions expressed are the speaker’s own and do not represent the views, thoughts, and opinions of the University of California. The material and information presented here is for general information purposes only. The "University of California" name and all forms and abbreviations are the property of its owner and its use does not imply endorsement of or opposition to any specific organization, product, or service.

Follow us on Twitter! @SacOrchards and @SJVtandv

Thank you to the Almond, Pistachio, Prune, and Walnut Boards of California for their kind donations. Thank you to Muriel Gordon for the music.

Come to an upcoming extension meeting!

Sacramento Valley

The 2026 North Sac Valley Olive Day is on Tuesday March 24

And the Nickels Field Day is on Tuesday May 19

San Joaquin Valley (scroll to the bottom)

Madera/Merced Pistachio Day is on Wednesday March 18

Today on the podcast we’ll be discussing Red Leaf Blotch a new invasive disease in California almond production. I want to offer my sincere apologies to listeners and to the Trouillas Lab for not getting this episode out promptly for maximum usefulness in the 2026 season. Although we are still in the red leaf blotch susceptibility window at the time of podcast airing – there’s not currently any rain in the forecast. 

Disease management           

The disease has a long latent period of 35 to 40 days, so by the time symptoms are visible, the infection window has long passed. This makes early, preventive management the key to controlling the disease. Based on 2025 field trials and growers’ experience in Spain, a three-spray program is recommended for orchards at risk. The first spray should be applied at petal fall (young leaflet emergence), followed by a second application two to three weeks later, and a third spray five to six weeks after petal fall if wet weather continues. These timings coincide with elevated inoculum levels of P. amygdalinum in orchards and a period of high leaf susceptibility to RLB. Similar timings for fungicide applications are used to manage other spring diseases like scab, shot hole, rust, and anthracnose, highlighting the need for an integrated approach to disease management in almond orchards.

Research trials in 2025 indicated that the most effective products to control RLB included various mixed fungicides with FRAC groups 3 + 7 (e.g. difenoconazole + pydiflumetofen); 3 + 11 (e.g. difenoconazole + azoxystrobin or tebucnonazole + tryfloxystrobin); 7 + 11 (e.g. fluopyram + trifloxystrobin, fluxapyroxad + pyraclostrobin, or boscalid + pyraclostrobin); 7 + 12 (adepidyn + fludioxonil), and FRAC 3-triazoles (metconazole or flutriafol). Growers are advised to rotate modes of action and follow all resistance management and product label guidelines to prevent product failure over time. Cultural practices, focused on eliminating the primary inoculum of infected fallen leaves, also can help mitigate the disease. These consist of removing leaf litter or applying urea to accelerate its decomposition. However, such strategies are only effective when applied over a wide area. Fungicides applied during bloom and after symptoms are visible are not effective.

2025 Fungicides, Bactericides, Biocontrols, and Natural Products for Deciduous Tree Fruit and Nut, Citrus, Strawberry, and Vine Crops in California

Mention of a pesticide does not constitute a pesticide recommendation, merely the sharing of research results. Consult your PCA and read the pesticide label. The label is law.

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The views, thoughts, and opinions expressed are the speaker’s own and do not represent the views, thoughts, and opinions of the University of California. The material and information presented here is for general information purposes only. The "University of California" name and all forms and abbreviations are the property of its owner and its use does not imply endorsement of or opposition to any specific organization, product, or service.

Follow us on Twitter! @SacOrchards and @SJVtandv

Thank you to the Almond, Pistachio, Prune, and Walnut Boards of California for their kind donations. Thank you to Muriel Gordon for the music.

Come to an upcoming extension meeting!

Sacramento Valley

Rice Production Workshop on March 18–19 at Lundberg Family Farms

The 2026 North Sac Valley Olive Day is on Tuesday March 24

And the Nickels Field Day is on Tuesday May 19

San Joaquin Valley (scroll to the bottom)

Madera/Merced Pistachio Day is on Wednesday March 18

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Like many fruiting orchard crops, olives benefit from boron fertilization. Elizabeth Fichtner (UCCE Tulare County) goes over how olives benefit from fertilization, as well as how to manage boron in olive orchards.

Episode transcript

You can sign up for the Rice Production Workshop here. Find out more about upcoming meetings in the San Joaquin Valley (scroll to the bottom) and the Sacramento Valley.

Mention of pesticide use does not constitute a pesticide recommendation. Always follow the pesticide label. Find out more at ipm.ucanr.edu/.

Thank you to the Almond, Pistachio, Prune, and Walnut Boards of California for their kind donations. Thank you to Muriel Gordon for the music.

The views, thoughts, and opinions expressed are the speaker’s own and do not represent the views, thoughts, and opinions of the University of California. The material and information presented here is for general information purposes only.  The "University of California" name and all forms and abbreviations are the property of its owner and its use does not imply endorsement of or opposition to any specific organization, product, or service.

The pistachio hull is critical for protecting the kernel. Insect pests can’t get through it until it begins to break down. However, it is known that hull integrity can change across years - some years hulls stay intact until harvest, and in other years it begins to break down earlier. Shuxiao Zhang, who used to be a student at UC Davis and is now working as a postdoctoral scholar at Stanford, and Georgia Drakakaki, a professor of plant sciences at UC Davis, decided to look into this. They were able to figure out the processes that led to hull degradation, the different ways degradation occur, and they were able to link in-field conditions to hull split. The Drakakaki lab has been doing extensive research into pistachio fruit development - Phoebe has interviewed the both of them on pistachio shell split in a previous episode.

Podcast transcript

You can sign up for the Rice Production Workshop here. Find out more about upcoming meetings in the San Joaquin Valley (scroll to the bottom) and the Sacramento Valley.

The views, thoughts, and opinions expressed are the speaker’s own and do not represent the views, thoughts, and opinions of the University of California. The material and information presented here is for general information purposes only. The "University of California" name and all forms and abbreviations are the property of its owner and its use does not imply endorsement of or opposition to any specific organization, product, or service.

Follow us on Twitter! @SacOrchards and @SJVtandv

Thank you to the Almond, Pistachio, Prune, and Walnut Boards of California for their kind donations. Thank you to Muriel Gordon for the music.

Leslie Holland, Assistant Professor at University of Wisconsin, Madison, shares the results of some of her work examining fungicides to suppress Botryosphaeria infections in almond pruning wounds as a Ph.D. student at UC Davis. Leslie shares what works, as well as the key tip to dealing with fungal infections in orchard crops: preventing the infection from occurring in the first place.

Podcast transcript

Mention of pesticide use does not constitute a pesticide recommendation. Always follow the pesticide label. Find out more at ipm.ucanr.edu/.

Thank you to the Almond, Pistachio, Prune, and Walnut Boards of California for their kind donations. Thank you to Muriel Gordon for the music.

The views, thoughts, and opinions expressed are the speaker’s own and do not represent the views, thoughts, and opinions of the University of California. The material and information presented here is for general information purposes only.  The "University of California" name and all forms and abbreviations are the property of its owner and its use does not imply endorsement of or opposition to any specific organization, product, or service.

Phoebe sits down with Elizabeth Fichtner to discuss the biology of pistachio bloom, how it impacts orchard design, and why picking the correct male pollinator is so important. She also goes over the research on artificial pollination of pistachio and why it may only be useful in very specific circumstances. In this episode, Elizabeth mentions that dust can cause parthenocarpy in pistachios; we posted an episode on this a few years ago.

Episode transcript

Find out more about upcoming meetings in the San Joaquin Valley (scroll to the bottom) and the Sacramento Valley!

The views, thoughts, and opinions expressed are the speaker’s own and do not represent the views, thoughts, and opinions of the University of California. The material and information presented here is for general information purposes only. The "University of California" name and all forms and abbreviations are the property of its owner and its use does not imply endorsement of or opposition to any specific organization, product, or service.

Follow us on Twitter! @SacOrchards and @SJVtandv

Thank you to the Almond, Pistachio, Prune, and Walnut Boards of California for their kind donations. Thank you to Muriel Gordon for the music.

One concern about growing cover crops is that they might compete with the orchard for water. This is an additional concern if you let cover crops continue to grow after bloom. Kosana Suvocarev (UC Davis) has been looking into this and has found some surprising results.

Podcast transcript

Find out more about upcoming meetings in the San Joaquin Valley (scroll to the bottom) and the Sacramento Valley!

The views, thoughts, and opinions expressed are the speaker’s own and do not represent the views, thoughts, and opinions of the University of California. The material and information presented here is for general information purposes only. The "University of California" name and all forms and abbreviations are the property of its owner and its use does not imply endorsement of or opposition to any specific organization, product, or service.

Follow us on Twitter! @SacOrchards and @SJVtandv

Thank you to the Almond, Pistachio, Prune, and Walnut Boards of California for their kind donations. Thank you to Muriel Gordon for the music.

Phoebe and Sam Sandovol Solis discuss the water outlook for 2026. They also discuss some things that everyone can do to maximize water infiltration. If you are interested in finding out more about groundwater recharge, you should check to see if your orchard block has favorable soil textures and is in a good location for it here. More information on applications for recharge can be found here. Phoebe interviewed two researchers in 2025 about the effects of wildfire smoke on orchards, which you may be interested in if 2026 ends up being a bad fire year (fingers crossed this isn’t the case!)

Episode transcript

Find out more about upcoming meetings in the San Joaquin Valley (scroll to the bottom) and the Sacramento Valley!

The views, thoughts, and opinions expressed are the speaker’s own and do not represent the views, thoughts, and opinions of the University of California. The material and information presented here is for general information purposes only. The "University of California" name and all forms and abbreviations are the property of its owner and its use does not imply endorsement of or opposition to any specific organization, product, or service.

Follow us on Twitter! @SacOrchards and @SJVtandv

Thank you to the Almond, Pistachio, Prune, and Walnut Boards of California for their kind donations. Thank you to Muriel Gordon for the music.

Self-fertile Nonpareil has the potential to be a gamechanger for California almond growers. Both Sierra Gold Nursery (FruitionOne™) and Burchell Nursery (Nonpareil SC+) announced in late 2024 their partnerships with biotech companies to develop a self-fertile Nonpareil. Both nurseries plan to begin delivering these trees to growers in 2027. However, many questions remain. In this episode Reid Robinson CEO of Sierra Gold Nursery discusses the development and future for FruitionOne™. You can learn more at: ohalo.com/fruitionone and contact Sierra Gold at: sierragoldtrees.com/contact

This episode does not constitute an endorsement, merely the sharing of an industry advancement that will be the subject of independent evaluation by the University of California Cooperative Extension in the years to come.

The views, thoughts, and opinions expressed are the speaker’s own and do not represent the views, thoughts, and opinions of the University of California. The material and information presented here is for general information purposes only. The "University of California" name and all forms and abbreviations are the property of its owner and its use does not imply endorsement of or opposition to any specific organization, product, or service.

Follow us on Twitter! @SacOrchards and @SJVtandv

Thank you to the Almond, Pistachio, Prune, and Walnut Boards of California for their kind donations. Thank you to Muriel Gordon for the music.