Oak Wilt
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Oak wilt is widespread in southern Wisconsin but in much of northern Wisconsin it is still a new and uncommon disease. View map. The cause of oak wilt Oak wilt is caused by a fungus, Ceratocystis fagacearum. The fungus invades areas inside the tree where water moves. Later, balloon-like bumps called tyloses are formed and they plug up the water's path through the tree. As water movement inside the tree is slowed, the leaves wilt and drop off the tree. Trees that can get oak wilt Oaks in the red oak group (black, northern red, northern pin and others with pointed leaf edges) get this disease most easily. Oaks in the white oak group (white, swamp white, burr and others with rounded leaf edges) are less susceptible. Preventing oak wilt Oak trees are most easily infected by overland spread in the springtime from bud swelling until two to three weeks past full leaf development. The Wisconsin DNR recommends that you avoid pruning, cutting or wounding oak from April through July in urban areas. Observations and unpublished research have shown that overland infection can occur after July, yet these mid-summer through early fall infections are not common. To take a very cautious approach, do not prune or otherwise wound oaks from April to October. In some years, spring comes much earlier. If daytime temperatures begin to reach the 50-degree mark, stop pruning oak at that time, even if it is still the middle of March. If you must prune when temperatures are above 50 degrees or between April and October, cover the wound surface with tree wound paint immediately. Tree wound paint can actually slow the natural closing of the wound, so limit the use of wound paint to the situation described above. Learn more about oak wilt |
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Oak wilt is widespread in southern Wisconsin but in much of northern Wisconsin it is still a new and uncommon disease. View map. The cause of oak wilt Oak wilt is caused by a fungus, Ceratocystis fagacearum. The fungus invades areas inside the tree where water moves. Later, balloon-like bumps called tyloses are formed and they plug up the water's path through the tree. As water movement inside the tree is slowed, the leaves wilt and drop off the tree. Trees that can get oak wilt Oaks in the red oak group (black, northern red, northern pin and others with pointed leaf edges) get this disease most easily. Oaks in the white oak group (white, swamp white, burr and others with rounded leaf edges) are less susceptible. Preventing oak wilt Oak trees are most easily infected by overland spread in the springtime from bud swelling until two to three weeks past full leaf development. The Wisconsin DNR recommends that you avoid pruning, cutting or wounding oak from April through July in urban areas. Observations and unpublished research have shown that overland infection can occur after July, yet these mid-summer through early fall infections are not common. To take a very cautious approach, do not prune or otherwise wound oaks from April to October. In some years, spring comes much earlier. If daytime temperatures begin to reach the 50-degree mark, stop pruning oak at that time, even if it is still the middle of March. If you must prune when temperatures are above 50 degrees or between April and October, cover the wound surface with tree wound paint immediately. Tree wound paint can actually slow the natural closing of the wound, so limit the use of wound paint to the situation described above. Learn more about oak wilt |
