Troubleshooting
English Walnut 'Howard' problems — and how to fix them
English Walnut 'Howard' (Juglans regia 'Howard') is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Walnut blight
Xanthomonas bacterial disease blackens catkins, nuts and shoots in wet springs; copper sprays at budbreak and late-leafing cultivars reduce loss.
Codling moth
Larvae bore into developing nuts causing drop and kernel damage; monitor with pheromone traps and time controls to egg hatch.
Zinc/boron deficiency
Walnuts are prone to micronutrient shortfall — little-leaf and poor nut set; correct with foliar zinc and soil/foliar boron after testing.
Crown and root rot
Phytophthora in wet or poorly drained soil kills the lower trunk; plant high on well-drained ground and keep irrigation off the crown.
Prevent english walnut 'howard' problems before they start
Most english walnut 'howard' issues are care-mismatch, not bad luck. Dial in the basics:
Looking for english walnut 'howard' in general rather than its problems? Read the full english walnut 'howard' care guide — light, water, soil and feeding.
English Walnut 'Howard' problems — FAQ
Why is my english walnut 'howard' walnut blight?
Xanthomonas bacterial disease blackens catkins, nuts and shoots in wet springs; copper sprays at budbreak and late-leafing cultivars reduce loss.
Why is my english walnut 'howard' codling moth?
Larvae bore into developing nuts causing drop and kernel damage; monitor with pheromone traps and time controls to egg hatch.
Why is my english walnut 'howard' zinc/boron deficiency?
Walnuts are prone to micronutrient shortfall — little-leaf and poor nut set; correct with foliar zinc and soil/foliar boron after testing.
Why is my english walnut 'howard' crown and root rot?
Phytophthora in wet or poorly drained soil kills the lower trunk; plant high on well-drained ground and keep irrigation off the crown.