What a difference a year makes! Last year, growers were well into the irrigation season by March 1st, while this year, we will need to be careful not to initiate irrigations too soon. Wet Spring conditions, particularly saturated soils, are conducive to early disease pressure, including Phytophthora and other root diseases. One strategy growers can implement to improve their odds of preventing infection is properly timing their initial irrigations.

Growers are likely using their irrigation systems in short sets to deliver much needed fertilizer to their orchards. With soil conditions so wet, growers will need to properly assess both soil moisture as well as orchard water demand before initiating longer irrigation runtimes. Probe Schedule is an excellent tool for understanding soil moisture conditions associated with timing irrigations, while Stem Water Potential can provide insight into tree water stress levels.

Probe Schedule and other soil moisture monitoring tools can effectively provide a snapshot of soil moisture conditions and could be coupled with the Moisture Depletion Method to accurately initiate irrigations. The Soil Moisture Depletion Method requires an understanding of the effective rooting depth as well as the general soil type of the field. The user then estimates the amount of water that can be held in the effective rooting depth and then track evapotranspiration to understand when enough soil moisture has been removed to warrant an irrigation. Probe Schedule can also help determine this threshold by giving growers a visual representation of moisture levels at different depths.

 

 

Stem Water Potential, as measured with a pressure chamber, can help growers understand how stressed a particular tree is at a particular time. As orchards begin to dry out, growers can implement these measurements into their decision-making process so as not to initiate irrigation until tree stress warrants an application. Wilbur-Ellis has skilled pressure chamber operators and can be consulted for specific strategies or thresholds for these measurements if desired. As we move through Spring, it seems that soil moisture will again be top of mind for some growers, but this year the focus will be regarding extreme moisture and not the lack thereof.

 

Matt Comrey // Wilbur-Ellis Sales Manager