Mitigating Tree Nut Stress and Disease Requires a Multi-Pronged Irrigation Approach By MATT COMREY | Technical Nutrition Agronomist, Wilbur-Ellis Agribusiness
Flush lines regularly to prevent clogging, particularly after fertilizer injections (all photos courtesy Wilbur-Ellis Agribusiness.)
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ut growers are essentially paid the season, rather than honing in on in two ways: they can either evapotranspiration (ET) rates. produce higher yields or reduce the number of deductions from the So the question for CCAs and PCAs is, processor. When nut trees aren’t “How do we help growers implement a receiving enough water, you’ll see an strategic irrigation schedule?” My anincreased number of blanks, shriveled swer starts and ends with measurement. kernels and pinched kernels. It’s also When you ask growers how much water common to see more disease and mite they’re putting out, they often come activity in the orchard. All of these back with a number of hours irrigated. issues can hurt final nut grade and yield, But this number does not tell you how which ultimately affects grower payouts much water is being applied to an orfrom the processor. chard; that can be drastically different based on application rates. During this tight water year, it’s more important than ever to help growers The first step in making the most of implement a science-based approach irrigation is working with your growto reduce the risk of disease and ers to understand how many inches maximize orchard yields. In years of of water per acre of soil the irrigation drought, salinity levels in the soil are system puts out per hour. This piece going to rise, making it critical to keep of information is often overlooked but orchards at proper field capacity so that is essentially the backbone of a good trees do not suffer from physiological irrigation schedule. Everything else drought stress. should be calculated based on that application rate. When water is limited, This is not as simple, however, as ensur- it’s also helpful to know the exact depth ing the right amount of water is applied of soil that needs to be wetted to avoid to the orchard. Growers are going to overirrigating. be pressured to match water deliveries to crop stage and demands throughout 26
Progressive Crop Consultant
July / August 2021
Measuring Orchard Demands
After the exact application rate is determined, growers can start designing an irrigation schedule that meets the needs of their orchards. Irrigation scheduling maximizes the use of available water by applying the exact amount of water needed to replenish soil moisture. This practice offers growers numerous potential benefits: • Possibly reduces the grower’s cost of water through more efficiently timed irrigations. • Lowers fertilizer costs by limiting surface runoff. • Maximizes net returns by increasing crop yields and crop quality. • Aids in controlling root zone salinity accumulation through controlled leaching. • Decreases common disease pressures.