Fungus on Leaves? - Ask Extension
Hello, would you know what this white fungus is covering several leaves on our tree? This is North facing. Sorry I have forgotten what kind of tree t...
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Fungus on Leaves? #872874
Asked June 12, 2024, 8:00 PM EDT
Hello, would you know what this white fungus is covering several leaves on our tree? This is North facing. Sorry I have forgotten what kind of tree this is.
Thanks much, Elsa
Denver County Colorado
Expert Response
This looks like it might be a beech tree and I'm not sure that this is a fungus. In fact, it looks like it might be wooly aphids.
To determine if these are in fact aphids, take a closer look under the white fluff and see if there are aphid bodies hidden under the "snow".
These pictures from Oregon State University will give you an idea of what you are looking for:
https://agsci.oregonstate.edu/nurspest/aphids/woolly-beech-aphid
There should also be a fair amount of "honeydew" present. This is a sticky substance that aphids produce. Click on the link for Woolly Beech Aphid in the publication linked below and you'll be able to clearly see what the honeydew looks like up close:
https://ipm.ucanr.edu/PMG/GARDEN/PLANTS/INVERT/woolaphids.html
The least invasive management technique for aphids is to spray them with a strong jet of water. This can crush their soft bodies, and knock them to the ground. Aphids are not good flyers so this is typically enough to disrupt their colonies. However, the "wool" can act like a waxy coating, so this may not work as well with woolly aphids. In addition to the water, you may need to physically brush them off the leaves.
A large, healthy tree shouldn't be too effected by them. However, if you feel they are threatening the health of your tree, the publication linked above has information on ways to manage them.
Since your tree isn't very large yet, you can spray them with with horticultural oil or insecticidal soap. When the tree is dormant, you can spray the end of branches with horticultural oil to disrupt their eggs.
Insecticidal soap or horticultural oil can be purchased at local garden centers.
To determine if these are in fact aphids, take a closer look under the white fluff and see if there are aphid bodies hidden under the "snow".
These pictures from Oregon State University will give you an idea of what you are looking for:
https://agsci.oregonstate.edu/nurspest/aphids/woolly-beech-aphid
There should also be a fair amount of "honeydew" present. This is a sticky substance that aphids produce. Click on the link for Woolly Beech Aphid in the publication linked below and you'll be able to clearly see what the honeydew looks like up close:
https://ipm.ucanr.edu/PMG/GARDEN/PLANTS/INVERT/woolaphids.html
The least invasive management technique for aphids is to spray them with a strong jet of water. This can crush their soft bodies, and knock them to the ground. Aphids are not good flyers so this is typically enough to disrupt their colonies. However, the "wool" can act like a waxy coating, so this may not work as well with woolly aphids. In addition to the water, you may need to physically brush them off the leaves.
A large, healthy tree shouldn't be too effected by them. However, if you feel they are threatening the health of your tree, the publication linked above has information on ways to manage them.
Since your tree isn't very large yet, you can spray them with with horticultural oil or insecticidal soap. When the tree is dormant, you can spray the end of branches with horticultural oil to disrupt their eggs.
Insecticidal soap or horticultural oil can be purchased at local garden centers.
