moonglow pear tree - Ask Extension
Leaves are turning black
Knowledgebase
moonglow pear tree #143055
Asked July 25, 2013, 8:49 AM EDT
Leaves are turning black
Barry County Michigan
Expert Response
I’m sorry to hear about your pear tree. Without seeing your
tree leaves it is hard for me to say exactly what is causing the leaves to turn
black. I can suggest a few problems which can cause this to happen and a few
more things for you to look at.
When observing black leaves on pear trees it is important to
rule out fire blight. This is a serious disease that can actually
kill the tree . Fire blight is a bacterial disease which is difficult to
manage. The leaves on the branch will have a scorched look and the end of the
branch looks like a shepherd's hook. The shepherd's hook is a key diagnostic
sign. The first sign is watery, light
tan bacterial ooze that exudes from cankers (small to large areas of dead bark
that the pathogen killed during previous seasons) on branches, twigs, or trunks.
The ooze turns dark after exposure to air, leaving streaks on branches or
trunks. However, most cankers are small and inconspicuous; if your tree has
fire blight, then, yes, absolutely, you should prune the branch out. Prune
several inches back into healthy wood, and dip the pruning shears in rubbing
alcohol or a 10% bleach solution between each cut. Newer Moonglow Pear Tree cultivars
have fire blight resistance. If this is a young tree this may not be the
problem. Here is a link that gives you a lot of information on fire blight: http://extension.usu.edu/files/factsheets/Disease%20027%20UPDC%20Fire%20blight.PDF
A less serious possibility is aphids. Aphids attack almost all types of trees and shrubs, sucking sap from twigs, stems or from leaves, causing them to curl. Large infestations reduce plant growth and vigor. • Most aphids excrete large quantities of honeydew, a sweet, sticky substance that attracts wasps, ants and bees and can serve as a medium on which black fungus can grow. If this is black fungus mold you should be able to wipe it off. In this case a strong spray of water may help to remove some of the Aphids. Depending on the severity of the infestation, the tree may lose its leaves but will survive. Use a dormant spray in early spring.
Pear Trips another insect that attacks pears and will cause leaf damage but the description does not match your description. Leaves appear mottled yellow to green brown, dwarfed and cupped with brown margins. This effect often resembles late frost damage. Severely attacked trees will drop all their leaves followed by refoliation in several weeks.
For a better diagnosis I’d suggest you take a sample to your local Extension Office. If your Extension Office does not have a Diagnostic Lab you can send the sample to Michigan State University. http://pestid.msu.edu/ for submission form, address ,and fees.
A less serious possibility is aphids. Aphids attack almost all types of trees and shrubs, sucking sap from twigs, stems or from leaves, causing them to curl. Large infestations reduce plant growth and vigor. • Most aphids excrete large quantities of honeydew, a sweet, sticky substance that attracts wasps, ants and bees and can serve as a medium on which black fungus can grow. If this is black fungus mold you should be able to wipe it off. In this case a strong spray of water may help to remove some of the Aphids. Depending on the severity of the infestation, the tree may lose its leaves but will survive. Use a dormant spray in early spring.
Pear Trips another insect that attacks pears and will cause leaf damage but the description does not match your description. Leaves appear mottled yellow to green brown, dwarfed and cupped with brown margins. This effect often resembles late frost damage. Severely attacked trees will drop all their leaves followed by refoliation in several weeks.
For a better diagnosis I’d suggest you take a sample to your local Extension Office. If your Extension Office does not have a Diagnostic Lab you can send the sample to Michigan State University. http://pestid.msu.edu/ for submission form, address ,and fees.
