As in all living beings, nutrients play a fundamental role in the plant cycle and its optimal development. In perennial fruit trees, the greatest uptake of nutrients occurs between flowering and vegetative growth, as Bernardita Sallato, Tree Fruit Extension Specialist at Washington State University, explains in her article “Nutrient Management in Sweet Cherries.”
But what aspects should be considered? What is the appropriate time for nutrient application? And what nutrients? Below a summary of the specialist’s research, who takes as an example the production in Eastern Washington.
Nutrients:
Nutrient Uptake Timing: Most nutrient uptake in perennial fruit trees, such as sweet cherries, occurs between bloom and rapid vegetative growth. Sweet cherry root growth begins when soil temperatures reach approximately 59°F during spring, usually after bloom.
Mobile Nutrients: Mobile nutrients like Nitrogen (N) should be managed carefully due to their high demand in sweet cherries. Recommendations include calculating N demand based on expected yield and considering soil, amendments, and water inputs.
Phosphorus (P) Management: Phosphorus, on the contrary, is less mobile in both soil and plant, with low demand compared to Nitrogen (N) and Potassium (K). Soil tests for P-Olsen levels are recommended, and applications should be made during soil preparation before planting.
Potassium (K) Management: K mobility depends on soil texture. Deficiency is infrequent, but excessive levels can affect fruit quality. Soil levels should be maintained between 150 to 300 mg/kg. Timing of application varies based on soil texture.
Calcium (Ca) Management: Ca mobility in the soil depends on texture, and deficiencies are rare in places like Eastern Washington, for example. Leaf tissue tests and soil tests help determine Ca availability. CaCl2 post-harvest dipping can reduce rain cracking.
Magnesium (Mg) and Sulfur (S) Management: Mg and S are mobile in both soil and plant. Deficiencies are infrequent but can be corrected with applications of MgSO4 and sulfate-based fertilizers.
Boron (B) Management: B deficiency is common in Eastern Washington soils. Adequate B levels should be maintained, and applications should be carefully calculated to avoid toxicity.
Micronutrients (Fe, Mn, Cu, Zn) Management: These nutrients, essential for growth and development, may face reduced availability in high pH soils. Soil pH management is crucial, and chelated forms can be applied for better effectiveness.
Visual Symptoms and Diagnosing:
First, and as we have already mentioned, it is important to know our crop and understand its needs; our nutritional management program and also the results will depend on that. That said, one of the points to take into account is leaf tissue analysis to determine absorption and whether the trees are in poor or excessive condition.
As expected, visual symptoms can be useful in diagnosing nutrient deficiency or excess, but it is important to keep in mind that the symptoms can be confused with other problems. For example, insects, diseases, pesticide toxicity or abiotic stress associated with excess or lack of water, wind or heat, etc.
Nutrient management in sweet cherries is based on leaf tissue standards, useful to prevent deficiencies or toxicities. These standards were developed by determining nutrient concentration at maximum growth and have not taken into account fruit quality or storability (i.e., there are no nutritional standards related to optimizing fruit quality).
