How to Manage Pests

Pests in Gardens and Landscapes

Fertilizing

Young trees benefit from light applications of nitrogen after one growing season has passed. If tree shoot growth is limited, nitrogen may need to be applied. Keep the fertilizer at least 18 inches from the trunk and water well after application. Divide the year's fertilizer amount into three or more applications during spring, summer and fall. Water well after application. Fertilize as directed to avoid nutrient deficiencies.

Fertilizer Rates for Walnuts

  • For trees 1 to 2 years old an under 1-inch trunk diameter: 1 to 2 ounce actual N per tree=0.75 pound of ammonium sulfate
  • For trees 2 to 5 years old with 1- to 4-inch trunk diameter: 0.33 to 0.5 pound of actual N per tree = 1.75 to 2.5 pounds of ammonium sulfate.
  • For trees 6 to 7 years old with 4- to 7-inch trunk diameter: 0.5 to 0.75 pounds of actual N per tree = 2.5 to 3.75
  • For trees 8 to 10 years old with 7- to 10-inch trunk diameter: 0.75 to 1.5 pounds of actual N per tree = 3.75 to 7.5 pounds of ammonium sulfate
  • For mature trees: 1.5 to 3 pounds of actual N per tree = 7.5 to 15 pounds of ammonium sulfate.
Healthy (left) and iron-deficient leaves
Healthy (left) and iron-deficient leaves
Leaf deficient in zinc
Leaf deficient in zinc

 

 


Statewide IPM Program, Agriculture and Natural Resources, University of California
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