2 tree species from Walnuts.
Deciduous Hardwood
Black walnuts are valuable timber trees that also create significant challenges in landscapes. They produce juglone, a chemical compound that is toxic to many plants including tomatoes, peppers, azaleas, and blueberries. Homeowners frequently need consultations about what can and cannot grow near black walnut trees. The nuts are enclosed in thick green husks that stain everything they contact a deep brown-black. Nut drop creates mess and slip hazards, and the husks attract flies. Despite these issues, large black walnut trees are worth significant money as timber. An arborist should always assess the timber value before quoting removal. Thousand cankers disease, caused by a bark beetle and associated fungus, is an emerging threat.
$1,500-$4,000 (removal)
Deciduous Hardwood
English walnuts are the commercial nut-producing walnut widely grown in California and planted as landscape trees across the South and West. They produce juglone like black walnuts but in lower concentrations. English walnuts are grafted onto black walnut rootstock for commercial production, and the graft union can be a point of failure in older trees. The wood is less valuable than black walnut for timber but still desirable. Walnut blight is the most common disease, causing black lesions on nuts and shoots during wet springs. Codling moth and walnut husk fly are the primary insect pests. English walnuts are less cold-hardy than black walnuts and suffer frost damage to new growth in zones 5-6.
$1,000-$3,000 (removal)