Jaime Ott, UCCE Tehama, Shasta, Glenn, Butte Counties

July leaf samples are our best tool for understanding the nutrient status of our trees. While nutrient levels in leaves change rapidly earlier in the season, by July they have stabilized and can provide us with useful information about how well our fertility program this year matched our trees’ nutrient needs.

Critical values for July leaf samples are shown in Table 1. Keep the results with your fertilizer application and yield records to better evaluate and estimate future fertilization needs. See “July Leaf Sampling: A Critical Task in Prune Production” by Luke Milliron for detailed information about how to take and interpret July leaf samples.

Table 1. Critical nutrient levels for prune leaves sampled in July (fully expanded leaves from nonbearing spurs).

Critical values for Prune July leaf samples