July Prune Orchard Management Considerations

Franz Niederholzer, UCCE Farm Advisor, Colusa and Sutter/Yuba Counties
Luke Milliron, UCCE Farm Advisor, Butte, Glenn and Tehama Counties
Becky Wheeler-Dykes, Tree Crop Researcher, CSU Chico

Please note that the following are general recommendations intended to help you keep track of regular practices in a busy time; the optimal timing for management practices may vary based on specific location and conditions.

  • Anticipating harvest timing. Once the first healthy fruit in the orchard start changing color along the suture (see photo below), fruit should be ready to harvest in roughly 30 days. The UC prune harvest prediction model anticipates harvest in the Sacramento Valley starting roughly in the last week of August based on regional bloom dates and CIMIS weather station data. The exact date will vary from block to block; however, indications are that harvest will be in the second half, not the first half, of August in many prune growing areas.
  • Collect leaf samples to gauge what nutrients are sufficient, deficient and perhaps over-supplied. Adjust the rest of the year’s nutrient management program and next year’s nutrient plan accordingly. Collect from at least 25 trees, gathering 1-2 leaves per tree from non-bearing spurs. A table listing critical levels of essential nutrients in prune appears after this article.
  • Fruit brown rot treatment sprays, where deemed necessary based on observations and block history, should begin 4-6 weeks before harvest. These preventative sprays are only useful on uninjured fruit. Check with your processor regarding fungicides that are approved for use

Critical Nutrient Levels for Prune Leaves* Sampled in July

*Fully expanded leaves from non-bearing spurs sampled in July. Click HERE for sampling protocol details.

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