What’s wrong with my pawpaw tree - Ask Extension
Hi! We moved into a house in College Park, Maryland three years ago with five pawpaw trees. I don’t know how old the trees are, but they have fruite...
Knowledgebase
What’s wrong with my pawpaw tree #873631
Asked June 18, 2024, 2:27 PM EDT
Hi! We moved into a house in College Park, Maryland three years ago with five pawpaw trees. I don’t know how old the trees are, but they have fruited every year. The tallest tree in our little grove (15-20 ft high) is suffering while the others seem to be thriving, with full leaves and lots of fruit. This spring, we noticed that it had many dead branches (all on one side of the tree) and removed a few of them. Now the tree looks close to death. Can you diagnose what’s wrong with it? It gets the same amount of water and sun as the others in its cohort. Could the pruning have been done incorrectly and hurt it?
All the trees are mulched but we allowed the violets to grow through. This tree is tallest and also closest to the house. I do not see any bugs or obvious signs of disease.
Prince George's County Maryland
Expert Response
This degree of foliage collapse is unfortunately not something we expect the tree to recover from, though it's hard to tell what the exact cause was. Our primary suspect is either Verticillium Wilt or moisture stress (too wet or dry at one point) in the root zone. While pawpaw is listed as one of the tree species resistant to Verticillium Wilt, they aren't necessarily immune, and the genetic differences from one tree to another may mean that some individuals are more inherently vulnerable than others.
The Verticillium fungus can enter tree tissues through wounds (though it can also enter intact tissues), but this originates in the root system, not above-ground branches. While the branch stubs pictured look a bit too close to the trunk, it's hard to say if any wood decay entered the stubs or the trunk. Even if it did, it didn't necessarily cause canopy dieback this extensive or extreme, though.
Might anything have injured roots from either construction digging or utility work in the past three years? Or, is the soil in that part of the yard well-drained, or does it tend to skew wet (any downspout outlets close by?) or dry out quickly? If a buried rock(s) or other debris, not uncommon from home construction (even years ago), or another natural obstacle, is present under part of the tree's root system, that can affect how wet or dry the soil gets, potentially stressing the tree. The fact that the other trees are okay doesn't necessarily mean this tree's soil profile has the same conditions, since sometimes interference from stones (etc.) can be very localized.
For now, this individual tree should be removed since it looks too declined to recover. Since they do have better-than-average resistance to Verticillium, you could try planting another pawpaw if you wanted to replace that tree. Otherwise, putting in another tree/shrub species (that is also listed as resistant, just in case the fungus is responsible) would be fine.
Miri
The Verticillium fungus can enter tree tissues through wounds (though it can also enter intact tissues), but this originates in the root system, not above-ground branches. While the branch stubs pictured look a bit too close to the trunk, it's hard to say if any wood decay entered the stubs or the trunk. Even if it did, it didn't necessarily cause canopy dieback this extensive or extreme, though.
Might anything have injured roots from either construction digging or utility work in the past three years? Or, is the soil in that part of the yard well-drained, or does it tend to skew wet (any downspout outlets close by?) or dry out quickly? If a buried rock(s) or other debris, not uncommon from home construction (even years ago), or another natural obstacle, is present under part of the tree's root system, that can affect how wet or dry the soil gets, potentially stressing the tree. The fact that the other trees are okay doesn't necessarily mean this tree's soil profile has the same conditions, since sometimes interference from stones (etc.) can be very localized.
For now, this individual tree should be removed since it looks too declined to recover. Since they do have better-than-average resistance to Verticillium, you could try planting another pawpaw if you wanted to replace that tree. Otherwise, putting in another tree/shrub species (that is also listed as resistant, just in case the fungus is responsible) would be fine.
Miri
