Fertility is one of the cornerstones of Agronomy, and for hazelnuts, it is one of the biggest contributors to yield and quality. In testing nuts for proper fill, fertility was the second largest contributing factor after water availability, in two small trials we performed in 2017 and 2018. While dry spring fertilizer is the most cost-effective application, foliar nutrients are an important way of providing nutrients and other beneficial compounds to the trees directly where the tree will use them. Use caution when choosing foliar products as some compounds won’t effectively pass into the leaves. We recommend using a tested program that has demonstrated yield and quality benefits over time.
Micronutrients like Zinc and Magnesium are important for promoting leaf growth. Boron is naturally low in western Oregon soils and is critical for proper nut set. Calcium is good for cell wall integrity and shell strength. Kelp is often thought of with skepticism by growers, but it has been repeatedly shown to reduce tree stress and promote proper hormone balance. Consult your agronomist on what the proper combination is for your trees. Take care when applying as high heat can cause leaf margin burn. Spray in the mornings or evenings and avoid spraying to runoff. Take care of your trees and they will provide for you over many years.