California Almonds: 8 Focus Points For May Orchard Management

Almonds after rain. ©Sara Savary, AgFax Media

Now that we have crept into May, here are 8 key management points to keep in mind this month. If you need better management for your business and want to implement new technological strategies, then consider using Bamboo Solutions.

#1 Monitor moisture.

Monitor stem water potential using the pressure chamber and soil moisture sensors for irrigation timing (when and how long).

Also, use irrigation water analyses on an ongoing basis to know what’s in your water as the season progresses. Overall salinity, chloride, sodium, and boron can change with the water source (canal versus well water) and time of the year.

#2. Pull together your navel orangeworm plan.

Track NOW populations and develop a hull split/harvest timing NOW plan.

Egg traps project when egg laying is likely to begin for later generations based on a spring biofix.

Pheromone traps (catch males but are ineffective near mating disruption products) and bait-bag traps (catch females) track flights and relative pest levels.

Here is more info on NOW management.

#3. Scout for spider mites (and their enemies).

Monitor for spider mites and their predators (especially six-spotted thrips) at least weekly. Watch hot spot areas, such as dusty or water-stressed parts of the orchard.

If you rely more heavily on groundwater this year after our dry winter, check irrigation salinity (EC) levels. Stress due to increased soil salinity from lower water quality could, in turn, increase mite pressure.

Early abamectin sprays provide excellent spider mite control for roughly 60 days if carefully applied, but they can flare mites going into harvest as the abamectin wears off and predator populations dwindle. Late mite flaring is expensive to control.

Here’s more info on mite management.

#4. Monitor nutrients.

Nitrogen (N): Assess your crop set and cut nuts to track nut development. Consider leaf sample results from last July and/or this spring and adjust the amount of nitrogen application needed before harvest – up or down depending on all information. Nuts use 80% of N by the first week of June, although timing varies, depending on the year and the crop load.

Potassium (K): Maintain leaf K levels in the adequate range (1.4%) through July to minimize spur death and reduced flower number (crop loss potential) next year. Almonds absorb K up to hull split, so the window for K fertilization is wider than N. See article on K nutrition in this newsletter.

#5. Keep an eye out for disease.

Monitor for Alternaria, rust, scab and anthracnose and treat if needed. Consider a follow up rust treatment before symptoms are visible – if orchard history and conditions indicate high vulnerability. Rotate the material’s site of action (FRAC Group) to avoid pesticide resistance.

Be aware of changes that possibly affect the use of propiconazole (Tilt, etc.) for nuts grown for the European Union export market. to the EU. See disease management details at:

#6. Watch for gopher signs.

Gophers kill almond trees. Also, gopher mounds potentially generate more dust during mowing. That, in turn, promotes more spider mite pressure. Take a look here at your control options.

Trapping works well and results improve when employees know how to find tunnels and set traps. Dr. Roger Baldwin, UC Extension Specialist, produced a video for training purposes.

#7. Look for escaped weeds.

Survey orchards for weeds missed by fall or winter treatment and plan ahead for your next fall/winter herbicide program.

#8. Scout for bugs.

Monitor closely for leaffooted and stink bugs.

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