Troubleshooting
English Walnut 'Hartley' problems — and how to fix them
English Walnut 'Hartley' (Juglans regia 'Hartley') 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
Bacterial blight (Xanthomonas) causes black lesions on leaves, shoots and developing nuts in wet springs; copper sprays at catkin emergence help, and late leafing in 'Hartley' offers some escape.
Codling moth
Larvae bore into nuts, causing drop and damage. Monitor with pheromone traps and treat at egg hatch where pressure is high.
Spring frost on young growth
Although 'Hartley' leafs out relatively late to avoid frost, an unusually late freeze can still kill emerging shoots and flowers; choose a frost-free site.
Pollination shortfall
'Hartley' is only partly self-fertile and its pollen shed may not overlap its female bloom well; planting a pollinizer such as 'Franquette' improves set.
Prevent english walnut 'hartley' problems before they start
Most english walnut 'hartley' issues are care-mismatch, not bad luck. Dial in the basics:
Looking for english walnut 'hartley' in general rather than its problems? Read the full english walnut 'hartley' care guide — light, water, soil and feeding.
English Walnut 'Hartley' problems — FAQ
Why is my english walnut 'hartley' walnut blight?
Bacterial blight (Xanthomonas) causes black lesions on leaves, shoots and developing nuts in wet springs; copper sprays at catkin emergence help, and late leafing in 'Hartley' offers some escape.
Why is my english walnut 'hartley' codling moth?
Larvae bore into nuts, causing drop and damage. Monitor with pheromone traps and treat at egg hatch where pressure is high.
Why is my english walnut 'hartley' spring frost on young growth?
Although 'Hartley' leafs out relatively late to avoid frost, an unusually late freeze can still kill emerging shoots and flowers; choose a frost-free site.
Why is my english walnut 'hartley' pollination shortfall?
'Hartley' is only partly self-fertile and its pollen shed may not overlap its female bloom well; planting a pollinizer such as 'Franquette' improves set.