Spots on arbutus unedo compacta leaves - Ask Extension
This strawberry tree has spots that start on the underside of the leaves and then as they progress to the top the leaves turn yellow, then brown, then...
Knowledgebase
Spots on arbutus unedo compacta leaves #876192
Asked July 07, 2024, 1:02 PM EDT
This strawberry tree has spots that start on the underside of the leaves and then as they progress to the top the leaves turn yellow, then brown, then fall off.
It seems to spread up the stem.
It was purchased / planted by a landscaper in fall 2023 and was exhibiting some symptoms at the time. Additionally, the tips of some stems became black last fall, and the flowering cluster black as well. I pruned some of the black off this spring, but not all.
Do you know what it is and if it can be stopped?
Linn County Oregon
Expert Response
Dear Bekah,
You have a fungal disease on the plant. It is generally called leaf spot. I am attaching 2 links that explain the disease and cultural changes you can make. RHS is an organization in the United Kingdom, the second is out of Missouri and a more generalized account for shade trees in general.
https://www.rhs.org.uk/disease/arbutus-leaf-spots
https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/insects-pests-and-problems/diseases/fungal-spots/leaf-spot-shade
Remove the infected leaves from the tree and the ground, prune off the infected twigs, limbs - do not put them in the compost pile, bag and trash them. When pruning, bring a bucket of alcohol or hydrogen peroxide with you and dip your pruners in the liquid every time you prune. You do not want to infect other parts of the plant. This should be done anytime you prune anything.
This fungus grows when there is a lot of rain which we have had. However, now that it is dry, a spray of sulfur (fungicide) after pruning would not hurt. Follow the directions and wear a hat, hazard glasses, long sleeves, long pants, boots and gloves for your protection.
Due to the excessive heat you need to wait for calm (no wind) and cooler temperatures under 80 degrees to spray. Sulfur will kill fungal spores but in excessive heat it may damage your plant too.
Mulch the area around the tree, add some liquid fish emulsion, again follow the directions and water deeply due to the excessive heat we are enduring. Mulch can be grass clippings if they have not had any weed and feed type herbicide on them. Wood chips, wood shreds, or straw; all work well. Keeping the roots cool and moist will keep the plant's stress level down. Make sure you leave 6 inches open space from the trunk to the mulch. Rodents like to hide and then gnaw on the trunk bark.
If you have further questions, please contact us again. Good luck with the plant. Mulching all your plants is a good idea especially with the heatwave that is predicted to continue to the end of the month.
You have a fungal disease on the plant. It is generally called leaf spot. I am attaching 2 links that explain the disease and cultural changes you can make. RHS is an organization in the United Kingdom, the second is out of Missouri and a more generalized account for shade trees in general.
https://www.rhs.org.uk/disease/arbutus-leaf-spots
https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/insects-pests-and-problems/diseases/fungal-spots/leaf-spot-shade
Remove the infected leaves from the tree and the ground, prune off the infected twigs, limbs - do not put them in the compost pile, bag and trash them. When pruning, bring a bucket of alcohol or hydrogen peroxide with you and dip your pruners in the liquid every time you prune. You do not want to infect other parts of the plant. This should be done anytime you prune anything.
This fungus grows when there is a lot of rain which we have had. However, now that it is dry, a spray of sulfur (fungicide) after pruning would not hurt. Follow the directions and wear a hat, hazard glasses, long sleeves, long pants, boots and gloves for your protection.
Due to the excessive heat you need to wait for calm (no wind) and cooler temperatures under 80 degrees to spray. Sulfur will kill fungal spores but in excessive heat it may damage your plant too.
Mulch the area around the tree, add some liquid fish emulsion, again follow the directions and water deeply due to the excessive heat we are enduring. Mulch can be grass clippings if they have not had any weed and feed type herbicide on them. Wood chips, wood shreds, or straw; all work well. Keeping the roots cool and moist will keep the plant's stress level down. Make sure you leave 6 inches open space from the trunk to the mulch. Rodents like to hide and then gnaw on the trunk bark.
If you have further questions, please contact us again. Good luck with the plant. Mulching all your plants is a good idea especially with the heatwave that is predicted to continue to the end of the month.
