California Walnuts: July’s Orchard Checklist – 4 Points

Photo: California Walnut Board.

#1. Codling moths

Check codling moth traps to pinpoint the third flight biofix (on average 1100 DD after the second biofix). Codling moth third flight has typically occurred in late July to early August in the Sacramento Valley more recently. The prolonged rain and cooler temperatures well into May this year will likely result in later-than-typical flights, depending on how summer conditions progress. More info here.

#2. Other pests

Continue weekly monitoring for husk fly and spider mites.

#3. Sample

Take July leaf samples to assess nitrogen, potassium, and zinc, as well as chloride and boron toxicity, depending on your area. Sample four terminal leaflets from at least 29 trees, each at least 100 feet apart, on the same rootstock scattered throughout the orchard.

#4. Water as needed

Just as with pulling the trigger on the start of irrigation, waiting until the pressure chamber indicates -2 or -3 bars below the fully watered baseline to trigger irrigations in-season can lead to healthier orchards and avoid nut quality degradation from over- or under-irrigation. Here are more details on interpreting pressure chamber readings.

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