It's difficult to determine from the symptoms alone what is causing damage to the tree. Daconil can help prevent some fungal infections, but not all, and it's possible a combination of overlapping stress factors have lead to decline. Has any herbicide been used around the tree's root zone (on either side of the fence) in recent years? If so, do you recall what active ingredients were in it? Some are more readily absorbed by tree roots and can lead to canopy dieback or foliage distortion.

Regarding watering, is the soil checked for moisture levels prior to irrigating? Ideally, the soil should become somewhat dry to the touch at a six-inch depth before a thorough soaking should be needed. Flowering dogwoods are sensitive to over-saturated roots, which is why we ask, since a wilted-like look is typical of trees experiencing moisture stress (whether too dry or too wet).

Do the dying branch tips have lots of scarring from old cicada egg-laying injuries from the mass emergence two years ago? If so, this might just be a delayed dieback from that damage, and new growth will gradually fill the canopy back in from points below that damage.

Are there any holes in the trunk (or thicker portions of the main branches affected by dieback)? Wood-boring insects like the aptly-named Dogwood Borer can kill branches by cutting-off their moisture and nutrient supply due to where that moth larva is feeding. These borers typically attack trees already under stress from other factors at the time the infestation began. Holes indicate at least one generation of borer adults have left the tree, though any inside the tree won't give much indication they are present unless found when splitting-apart infested wood that was pruned off. Dogwood Twig Borer, the pest listed just beneath the Dogwood Borer listing on the linked page, is another possibility.

For now, all you can do is to keep monitoring the tree for watering needs, prune off all leafless branches, and inspect the tree (and split-apart removed wood) for other symptoms. No insecticide will be effective if borers are currently inside the wood, nor would any treatment reverse herbicide exposure or a fungal infection in the roots or wood itself. If you prefer, you can also get an assessment from a certified arborist, whose second opinion can help with diagnosis and who can also look for sources of tree stress that can be addressed to prolong its life or help it to stabilize. Arborists can't cure every ailment or reverse decline, but in the event a treatment is warranted, they can usually apply them as they have a pesticide certification. Some arborists are employed by tree-care companies but others consult independently.

Miri

We are sorry that you did not receive our reply, which was sent on June 20th, 2023.
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Here was our answer: 

"It's difficult to determine from the symptoms alone what is causing damage to the tree. Daconil can help prevent some fungal infections, but not all, and it's possible a combination of overlapping stress factors have lead to decline. Has any herbicide been used around the tree's root zone (on either side of the fence) in recent years? If so, do you recall what active ingredients were in it? Some are more readily absorbed by tree roots and can lead to canopy dieback or foliage distortion.

Regarding watering, is the soil checked for moisture levels prior to irrigating? Ideally, the soil should become somewhat dry to the touch at a six-inch depth before a thorough soaking should be needed. Flowering dogwoods are sensitive to over-saturated roots, which is why we ask, since a wilted-like look is typical of trees experiencing moisture stress (whether too dry or too wet).

Do the dying branch tips have lots of scarring from old cicada egg-laying injuries from the mass emergence two years ago? If so, this might just be a delayed dieback from that damage, and new growth will gradually fill the canopy back in from points below that damage.

Are there any holes in the trunk (or thicker portions of the main branches affected by dieback)? Wood-boring insects like the aptly-named Dogwood Borer can kill branches by cutting-off their moisture and nutrient supply due to where that moth larva is feeding. These borers typically attack trees already under stress from other factors at the time the infestation began. Holes indicate at least one generation of borer adults have left the tree, though any inside the tree won't give much indication they are present unless found when splitting-apart infested wood that was pruned off. Dogwood Twig Borer, the pest listed just beneath the Dogwood Borer listing on the linked page, is another possibility.

For now, all you can do is to keep monitoring the tree for watering needs, prune off all leafless branches, and inspect the tree (and split-apart removed wood) for other symptoms. No insecticide will be effective if borers are currently inside the wood, nor would any treatment reverse herbicide exposure or a fungal infection in the roots or wood itself. If you prefer, you can also get an assessment from a certified arborist, whose second opinion can help with diagnosis and who can also look for sources of tree stress that can be addressed to prolong its life or help it to stabilize. Arborists can't cure every ailment or reverse decline, but in the event a treatment is warranted, they can usually apply them as they have a pesticide certification. Some arborists are employed by tree-care companies but others consult independently.

Miri"


Christine