For apple growers, particularly those cultivating ‘Honeycrisp’, precise fertilization is crucial for achieving optimal fruit quality and yield. Here’s a guide to help you manage your annual fertilization strategy effectively based on updated research and standards.

Importance of Leaf Sampling: Annual fertilization strategies should be informed by mineral nutrient values from leaf samples collected in late June to early July. For ‘Honeycrisp’ apples, the proper timing for collecting leaf samples is about one month earlier than for other varieties. This adjustment is due to two key factors:

1. Early Shoot Growth Cessation: ‘Honeycrisp’ trees typically stop their shoot growth by the third week in June, earlier than many other apple varieties.

2. Zonal Leaf Chlorosis: Development of zonal leaf chlorosis, which affects leaf nutrient concentrations, particularly nitrogen (N) status, can start showing symptoms as early as late June to mid-July.

Nitrogen (N) Fertilization: The recommended leaf concentration of N for ‘Honeycrisp’ is 2.0%, similar to ‘McIntosh’. Here are the specific guidelines based on leaf N levels:

– Leaf N < 2.0%: Apply 40-50 lb of N per acre per year to maintain tree vigor and prevent issues like biennial bearing.

– Leaf N between 2.0% and 2.25%: Reduce N application to 20 lb per acre to gradually lower the leaf N to the target 2.0%.

– Leaf N > 2.25%: Avoid ground-applied N to prevent excessive nitrogen levels.

Soil N applications should be made early in the season when shoots are actively growing, ideally before petal fall. Split applications at bud break and petal fall are recommended. For fertigation, target the period from bloom to the end of shoot growth (around the third week of June).

Post-harvest applications of foliar N can be beneficial, particularly for trees with leaf N below 2%. This helps promote root growth and replenish N reserves. Use 3% foliar urea (25 lbs/100 gal) in early October.

Potassium (K) Fertilization: ‘Honeycrisp’ requires less potassium than other varieties like ‘Gala’ or ‘Empire’. High levels of leaf K can lead to bitter pit, so K fertilization must be carefully managed. The optimal range for leaf K in ‘Honeycrisp’ is 1.0-1.3%.

– Leaf K < 1.0%: Apply 60-80 lb of K2O per year to maintain fruit size.

– Leaf K between 1.0% and 1.3%: Apply 30-50 lb of K2O per year to sustain good fruit size.

– Leaf K > 1.3%: Avoid K fertilization until levels drop below 1.3%.

Accurate leaf sampling and tailored fertilization strategies are essential for managing ‘Honeycrisp’ apple trees. By following these guidelines, you can ensure that your trees receive the right nutrients at the right time, leading to better fruit quality and yield. Always refer to your leaf analysis results from the previous summer to guide your fertilization decisions in the following season.

This article was posted in Apples and tagged Amaya Atucha, Apples, fertilization, fertilization strategies, Honeycrisp.