Boron Deficiency
Many commercial
19 host plants
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. PNW soils west of the cascades 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.