Growing the Valley

Winter sanitation is the foundation of navel orangeworm control, however orchard access can be difficult, particularly in wet winters. Houston Wilson, entomology specialist at UC Riverside, is part of a multidisciplinary team looking at sheep grazing in orchards. He has been looking at whether sheep eat mummy nuts, and how well they do it.

Episode transcript

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...

Phytophthora infections have become more common in pistachio. Alejandro Hernandez covers the biology of this disease, as well as his research on rootstock susceptibility and the efficacy of new fungicides. Please note that some of these fungicides are not registered for use in pistachio.

Episode transcript

Mention of a pesticide does not constitute a pesticide recommendation, and mention of specific trade names does not constitute an endorsement. Always follow the pesticide label. Find out more at ipm.ucanr.edu

The views, thoughts, and opinions expressed are the speaker’s own and do not re...

Phoebe got the chance to interview former orchard systems advisor Dani Lightle on band canker. There’s a lot we don’t know about infections, but she shares what we know about survival, disease latency, and ages of infection. She also runs through some past and ongoing research.

Mention of a trade name is not an endorsement or recommendation.

Thank you to the Almond Board of California and the California Pistachio Research Board for their support. Music by Muriel Gordon.

Fruit removal is a serious issue in table olive production, namely because the fruit are harvested before they are ripe. ACC, an ethylene precursor, has the potential to improve fruit removal (please note that the commercial product is not registered in olives yet and cannot legally be used).

Becky Wheeler-Dykes, an advisor in Glenn, Colusa, and Tehama Counties, has been examining its efficacy in olives with a team of researchers at UC Davis. She shares some preliminary, and promising results in this week’s episode.

Episode transcript

Mention of a pesticide does not co...

Anyone who has an irrigation system knows that it needs to be maintained for peak performance. Anyone who has an irrigation system also knows that almost everything seems to be more important in the moment than flushing those lines or checking pressures. A distribution uniformity test is a good way to assess the health of your irrigation system, but it isn’t always easy to figure out if the cost of making these fixes, particularly big fixes, will pencil out.

CURES got a grant a few years back to develop a tool to estimate the return on in...

In 2026 the Sacramento Valley prune industry is experiencing high fruit sets, high GDH 30, and a high cost of fruit thinning because of very diesel prices. Jaime Ott (UCCE Tehama), Domena Agyeman (UCCE Butte), and Franz Niederholzer (UCCE Colusa) break down prune grower crop management considerations given this tricky set of circumstances.

Upcoming Orchard Meetings:

The Almond Board of California also has four upcoming IPM meeting, tackling rodents, red leaf blotch, Carpophilus and other pests:

Bakersfield: Thursday, April 30

Wednesday, June 16, if you’re an almond variety nerd like me you can’t miss...

The 3rd Generation RAVT recently wrapped up, and Luke, Phoebe, and Roger sit down one final time to discuss the findings. While the overall results are discussed, they also discuss each of the strengths and weaknesses of the 13 remaining varieties. It’s a long episode, check out the transcript if you are interested in something specific to get the timestamp.

Episode transcript

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 gene...

Giulia Marino and Pat J Brown (both UC Davis) have been examining another potential influence on polyphenol deposition in pistachio: whether the pollen source impacts deposition rates. In this episode, Giulia shares her results, as well as some other unexpected findings from pistachio xenia (the effect of the pollen source on the fruit).

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 re...

Dr. Or Sperling (ARO-Volcani) and Zac Ellis (OFI) discuss the exciting 2025 results from their proactive irrigation scheduling application in California almond orchards.

You can ask questions and provide feedback to the researchers at:

Or Sperling: orsp@agri.gov.il or +972 52 6278189 

Zac Ellis: Zac.ellis@ofi.com (559) 303-0599

Maciej Zwieniecki: mzwienie@ucdavis.edu

Come to an upcoming extension meeting!

In the San Joaquin Valley:

UC Cooperative extension has a Regenerative Almond Orchard Field Day on Tuesday, April 21st at the UC Merced Experimental smart farm

Drs. Or Sperling (ARO-Volcani) and Maciej Zwieniecki (UC Davis) discuss their groundbreaking research on almond irrigation. That research has culminated in an exciting irrigation scheduling application. We also get an overview of almond production in Israel. The UC Davis Carbohydrate Observatory is also referenced.

Have feedback or questions for the researchers?

Or Sperling: orsp@agri.gov.il or +972 52 6278189 

Maciej Zwieniecki: mailto:mzwienie@ucdavis.edu

Zac Ellis (Olam): Zac.ellis@ofi.com (559) 303-0599

Come to an upcoming extension meeting!

In the San Joaquin Valley: Tomorrow Tuesday April 7 there is...

Polyphenol deposition in pistachio kernels, also known as internal kernel discoloration, is a harmless phenotype of pistachios, where dark coloration appears on the internal surface of the pistachio cotyledons (the two halves of the kernel). It started showing up widely in the late 2010s/early 2020s, and researchers Georgia Drakakaki, Phoebe Gordon, and Minmin Wang have been investigating it from different angles (Phoebe from the field perspective; Georgia and Minmin from the anatomical and physiochemical perspective). In this episode, they share some initial results. We still don’t know what truly causes it, but we have some answers to ba...

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 i...

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 an...

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...

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...

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 hu...

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...

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!

...

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 ma...

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 ca...

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 adva...

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 Tom Burchell owner of Burchell Nursery discusses the development and future for Nonpareil SC+. You can learn more at: burchellbreeding.com

This episode does not constitute an endorsement, merely the sharing of an industry advancement that will be the subject of independent evaluation by...

Dr. Themis Michailides (UC Davis Plant Pathologist at the Kearney Ag Center) provides a critical update on his lab’s research on the biology and management of walnut mold.

An article that is episode was based can be found at: sacvalleyorchards.com

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

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 pres...

Facing tightening SGMA regulations and the specter of future droughts, how should we be designing the almond orchard of the future? On the podcast, Franz Niederholzer discusses his idea of a test almond orchard at the Nickels Soil Lab with different rootstocks provided reduced irrigation treatments from planting onward. Should a grower provide full irrigation to fewer acres, or reduced irrigation to their existing farming footprint?

Come to an upcoming extension meeting!

2025 International School on Microirrigation for Crop Production: Class Lectures at UC Davis October 13-15, and field trips October 16-17.

The views...

Researchers have been conducting almond irrigation and other studies at the Nickels Soil Lab in Arbuckle, CA for over 50 years! On the podcast, Franz Niederholzer revisited research on early microirrigation, the consequences of late season drought in young almonds, and the implications of one-year of season-long drought in mature almonds. Dialing in irrigation is the greatest task for California orchardists, and we should continue to learn from the lessons of our predecessors. 

Come to an upcoming extension meeting!

2025 International School on Microirrigation for Crop Production: Class Lectures at UC Davis October 13-15, and field trips O...

Environmental bud failure showed up in almonds in a big way in 2025. From a subtle delay of leafing in parts of Nonpareil canopies throughout the Central Valley to some orchards in the northern Sacramento Valley with only half leaf out. This disorder also called leafing failure, severely affected many growers in the northern Sacramento Valley. Dr. Tom Gradziel (UC Davis) gets into the complexities of this disorder, as well as discussing the unusual bloom in 2025.  

Come to an upcoming extension meeting!

2025 International School on Microirrigation for Crop Production: Class Lectures at UC Davis October 13-15, a...

If you work in the almond industry, you likely know non-infectious bud failure (NBF) is bad news. However, do you understand why NBF happens, and that we’re likely to see it on future almond varieties, not just on Carmel? Tom Gradziel discusses the science behind NBF and the work UC researchers together with nurseries have done to make massive gains in addressing the problem.

You can lead more about managing NBF at: sacvalleyorchards.com/almonds/horticulture/non-infectious-bud-failure-management

Come to an upcoming extension meeting!

2025 International School on Microirrigation for Crop Production: Class Lectures at...

Regenerative agriculture is currently all the rage these days in some circles. With a broad range of practices that can be classified as regenerative, it still can feel like a mushy term that means different things to different people (which is actually by design). Amelie Gaudin sits down with Phoebe Gordon to discuss what qualifies as a regenerative practice, how the focus differs from “conventional” agriculture, and the science behind it (spoiler alert: you’re probably already familiar with a lot of it!).

Episode transcript

Come to an upcoming extension meeting!

And finally, the 20...

Walnut scale is a minute insect pest that can, if populations build high enough and kill fruiting wood. It can do this by directly allowing pathogens entry into walnut wood, or by weaking branches, making them more vulnerable to infection. In this episode In this episode, Elizabeth Fichtner discusses the lifecycle of the pest and control options. Note: while walnut scale does appear in almonds, this episode only covers walnuts.

Episode transcript

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

A great deal goes into a successful prune crop. In part two or a two-part podcast on prune crop phenology we complete the yearly cycle by talking about summer fruit growth, key financial considerations at harvest, and finishing the season strong in the postharvest period. Luke Milliron assembled an expert panel of UCCE Farm Advisors, Franz Niederholzer (UCCE Colusa), Jaime Ott (UCCE Tehama), and Becky Wheeler-Dykes to talk about each step in prune fruit development from buds to harvest and back-again.

If you missed part one, that’s where we discussed the crop phenology and key management ste...

A great deal goes into a successful prune crop. In part one of a two-part panel, Franz Niederholzer (UCCE Colusa), Jaime Ott (UCCE Tehama), Becky Wheeler-Dykes (UCCE Glenn) and host Luke Milliron (UCCE Butte) talk about the formation of fruit buds all the way through to fruit thinning in spring. Topics include weather at bloom, the importance of weather the 30 days after bloom, and a calculator that helps prune growers shaker thin fruit in order to produce a quality crop. We finish the first part of the yearly prune cycle by discus A great deal going into a successful...

.Oak root fungus (Armillaria root rot) is a devastating disease that can plague orchards generation after generation. Resistant rootstocks is the answer. Roger Duncan (UCCE Advisor Emeritus) discusses early findings in his ORF rootstock trial.

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.

Come to an upcoming extension meeting!

In the San Joaquin Valley: Tuesday August 19: Stone Fruit Roundtable in Dinuba.  

And finally, the 2025 International School on Microirrigation for Crop Production: C...

Phytophthora isn’t just an early season problem anymore. On this episode of the podcast, Dr. Jim Adaskveg (UC Riverside) talks warm season phytophthora management in almond. You can round out your phytophthora expertise by listening to earlier episodes with Dr. Greg Browne (USDA) covering Phytophthora in almond and walnut orchards, as well as an episode with Dr. Florent Trouillas on aerial phytophthora in almonds.

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.

Come to an...

We know pistachios, and we love to eat them. Despite pistachio ice cream being the objectively best way to consume this nut , the majority of pistachios are sold in-shell. Have you ever wondered how those shells split? In this episode, Phoebe sits down with Shuxiao (Susan) Zhang and Georgia Drakakaki, two of the authors of a recently published study on the mechanisms behind pistachio shell splitting. They discuss how the cells of a shell enable splitting, whether kernel size really does impact split percentage, and why Golden Hills has a higher split percentage than Kerman.

Podcast transcript<...

Johnsongrass can be a tough weed to control. Ryan Hill (UCCE Tehama, Shasta, Glenn) comes on the podcast to update us on the integrated year-round management of this perennial weed in orchards. UC ANR has great resources on distinguishing Johnsongrass and other young summer grass weeds. Johnsongrass identification photos can also be found on the podcast website. ANR also has a great guide to Johnsongrass biology and management.

Connect with a local UCCE weed expert! UC ANR has recently expanded their weed science team across the state. Ryan Hill (UCCE Tehama, Shasta, Glenn), and Clebson Goncalves (UCCE...

Dr. Pat J. Brown (UC Davis) discusses exciting new clonal rootstocks being developed by a team of UC and USDA researchers. Pat is looking for growers to trial these new clones, in particular K3 an exciting new rootstock that has produced good growth, yield, and very low crown gall. You can contact Pat at pjbrown@ucdavis.edu. Please also CC your local UCCE walnut farm advisor.

Come to an upcoming extension meeting!

In the Sacramento Valley:

North Sac Valley Groundwater and SGMA is on Tuesday, June 24

Save the date for Prune...

Three PhD entomologists with UC Cooperative Extension: Sudan Gyawaly, Jhalendra Rijal, and Houston Wilson discuss integrated management of the leaffooted and stink bug pest complexes in California nut crops. Be sure to first listen to part I where the three experts discuss phenology and monitoring of these pest complexes.

More information on controlling plant bugs in almonds and pistachios can be found on the UCIPM website; there are separate pages for stink bugs and leaffooted bugs, and in pistachio, small bugs.

Mention of a pesticide does not constitute a recommendation, merely the sharing...

Three PhD entomologists with UC Cooperative Extension: Sudan Gyawaly, Jhalendra Rijal, and Houston Wilson discuss the phenology and monitoring of the leaffooted and stink bug pest complexes in California nut crops. Including an exciting update from Houston Wilson (UC Riverside) on the trap and lure for leaffooted bug. Stay tuned for part two where the expert panel discusses the integrated management of these pests.

More information on controlling plant bugs in almonds and pistachios can be found on the UCIPM website; there are separate pages for stink bugs and leaffooted bugs, and in pistachio, small bugs.

Dr. Roger Baldwin (UCCE Specialist in Human-Wildlife Conflict Resolution) discusses orchard management of pocket gophers, ground squirrels, voles (meadow mice), roof rats, and deer mice. This is a compilation of two episodes from 2022, with Luke Milliron providing a new introduction with highlights from 2024/2025.

Skip to the pest you’re concerned about:

00:05:35 Pocket Gophers

00:35:12 Ground Squirrels

00:48:33 Voles/Meadow Mice

01:02:38 Roof Rats

01:12:39 Deer Mice 

2025 Update on Roof Rats: The Baldwin Lab (UC Davis) now has further data to show that the A24 trap did not end up wor...

Drs. Or Sperling (ARO-Volcani) and Maciej Zwieniecki (UC Davis) discuss their groundbreaking research on almond irrigation. That research has culminated in an exciting irrigation scheduling application. We also get an overview of almond production in Israel. The UC Davis Carbohydrate Observatory is also referenced.

Come to an upcoming extension meeting!

Sacramento Valley

San Joaquin Valley (scroll to the bottom)

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 fo...