Boron Deficiency
Many commercial
19 host plants
Last updated
Boron deficiency in holly causes irregularly shaped reddish or purplish spots on upper leaf surfaces and water-soaked appearance on lower leaf surfaces. As leaves age, spots enlarge with concentric rings bordered in yellow. Veins enlarge and may become prominent. Leaves defoliate prematurely. Soils in maritime regions west of mountain ranges are naturally low in boron. Apply 0.1 lb actual boron to soil in fall around each tree.
Management depends on catching it early. Scout susceptible plants regularly and remove affected tissue before the pathogen can spread. Improve growing conditions by addressing drainage, spacing, and irrigation practices. For persistent or severe cases, contact your local Master Gardener program or Extension office for treatment options specific to your host plants.
Quick Reference
Management
1 lb actual boron to soil in fall around each tree has been effective in 10-year-old plantings.
Cultural Controls
- It may be necessary to have the soil tested for boron.
- Amend the soil as recommended to correct the deficiency.
- Use caution, as excess boron is toxic to plants.
- Applying 0.1 lb actual boron to soil in fall around each tree has been effective in 10-year-old plantings.
- Younger trees require correspondingly less.
Soils west of the Cascade Range are naturally low in boron. Many crops in this region need supplemental boron application. Holly plantings are particularly affected.