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AlmondBeat 2023 #3: Humidity Alert! Over-Irrigating Opens The Door to Fungal Disease and Hull Rot

The 2023 almond growing season in California continues to bring unprecedented challenges and opportunities. It's time to pay close attention and take action to make the most of this unique season.


Mitigating humidity and its impact on your almond orchard through efficient irrigation schemes is essential.


The National Weather Service is forecasting humidity to be very high, averaging 75% the week of June 5th in California’s Central Valley. “The average ET was historically low last week with an average of 1.8, but it’s about to have a 20% drop this week to 1.5” says Joseph Jackson, CA CSM Director.


Now is the time to decrease irrigation duration NOT frequency. Dark-green indicators on the app signify over-irrigation, which should be avoided during this critical period. Standing water and high humidity will open the door to fungal disease and hull rot in almonds.


AlmondBeat 2023 #3: 5 Strategies to Navigate Humidity and Maximize Your Almond Crop's Success

Provided by Phytech Agronomy Experts, Ziv Attia and Mark Sherfy.






Effect of Stress on Nut Fill and Expected Crop Load

This is the time of year when growers should focus on maximizing the size of the nuts, which undergo rapid development from March to mid-June before reaching their final hardening stage.


During this period, the tree channels sugars to fill the nuts. However, excessive stress days can force the tree to reallocate its resources, compromising both sugar and water availability for the kernel resulting in shrinkage.


To ensure optimal nut fill, it is crucial to avoid consecutive orange and yellow statuses by closely monitoring Phytech's plant-status indicators. Another helpful measure is to keep an eye on the increasing Maximum Daily Shrinkage (MDS) numbers, which can serve as an early warning sign.


During this critical period, it is important to steer clear of over-irrigation, as indicated by the dark-green indicators on the app. Excessive watering can lead to standing water and high humidity, creating favorable conditions for fungal diseases and hull rot to develop in almond trees.


If stress is managed poorly over the next couple of weeks, then the June drop may be more severe, and crop load will suffer.


Trees Acclimating to the Environment

In the coming weeks, trees will regulate themselves, resulting in partially closed stomata that are trying to compensate for warming temperatures. However, until that point, it is crucial to implement proper irrigation methods, such as increasing irrigation frequency to mitigate the significant levels of stress.


With approximately 3 to 5 weeks remaining for nut fill, depending on the variety, effectively managing stress becomes crucial to maintain the current crop load for this season. Inadequate stress management during the next few weeks may lead to a more severe June drop and negatively impact the crop load.


Typically, at this point in the season, the trees have already been exposed to some heat. However, this year, they will face it at a relatively late phenological stage, which can cause a more significant shock to their system.


The recommended solution is to maintain adequate moisture in the upper foot of the soil, allowing the trees to readily access water and recover quickly from stressful conditions. This approach is closely connected to our next irrigation tip: focusing on irrigation frequency.


Proper Irrigation Techniques



Emphasizing the importance of irrigation frequency instead of large quantities and long durations, we strongly recommend switching to short bursts or pulses during irrigation.


Amidst high humidity and rising temperatures, traditional irrigation practices may not always be the most effective way to combat stress in almond trees. Instead of applying large amounts of water, consider implementing high-frequency/lower-quantity irrigation plans. This approach ensures that trees receive more frequent "drinks" to aid in their recovery during heat waves while not rotting in standing water.


Advantages of Automation During Nut Fill

Automation can be a game-changer during the crucial nut-fill stage of almond production. Phytech's advanced monitoring system in partnership with automation streamlines the process, allowing you to optimize irrigation, adjust schedules based on weather conditions, and ensure precise water delivery when and where it is most needed. With automation, you can take control and maximize the yield potential of your almond crop.


Stay Ahead with Phytech.

As the 2023 almond growing season progresses in California, it is crucial to mitigate humidity, while staying ahead of the heat and its impact on your orchard.


By implementing proper irrigation techniques, such as adjusting frequency and optimizing water delivery, you can mitigate stress and optimize nut fill. Additionally, automation tools can revolutionize your almond farming experience, providing precise irrigation control.


With these strategies and technologies, you can navigate the challenges of the growing season and maximize your almond crop's success.


Stay tuned for more insights and tips in our upcoming AlmondBeat reports.


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