As apple plants mature and enter their 10th year and beyond, it can become challenging to maintain their health and productivity. Regular fertilization and careful monitoring of pests and diseases is needed to ensure the plants stay healthy and produce quality fruit. Two important factors to consider when fertilizing apple plants are the use of SP (soluble phosphate) and MOP (muriate of potash).
SP is a common fertilizer used to promote root growth and establishment in young plants. However, as apple trees age, their need for SP decreases. In fact, too much SP can cause an imbalance in nutrient uptake and interfere with the absorption of other essential nutrients, such as iron and zinc. As a general guideline, apple trees in their 10th year or older should receive no more than 1 pound of SP per tree per year.
MOP, on the other hand, is critical to the health and productivity of mature apple trees. Potassium is an essential nutrient for fruit production, and MOP is a reliable source of this nutrient. MOP is also known for its ability to increase the tree’s resistance to disease and environmental stressors. Apple trees in their 10th year or older should receive approximately 2-3 pounds of MOP per tree per year.
It is important to note that the exact amount of SP and MOP needed will vary depending on factors such as soil type, weather conditions, and the specific nutritional needs of the apple variety. To ensure accurate and effective fertilization, it is recommended to have soil tests performed and to consult with a horticulturist or agricultural extension agent before applying fertilizers.
In conclusion, as apple trees mature beyond their 10th year, the use of SP should be reduced, while MOP becomes increasingly important. By providing appropriate amounts of these two fertilizers, along with careful pest and disease management, apple growers can maintain the health and abundance of their trees well into their adulthood.