White growth on magnolia tree - Ask Extension
Hi,
We recently moved to a new house in Franklin county and are experiencing a pest or mold problem with our magnolia tree. It is dripping sap and ...
Knowledgebase
White growth on magnolia tree #875495
Asked July 01, 2024, 12:57 PM EDT
Hi,
We recently moved to a new house in Franklin county and are experiencing a pest or mold problem with our magnolia tree. It is dripping sap and has white fuzzy growth up some of the branches. There are also little fuzzy bugs we have noticed on other plants. I suspect it is infested with scale. Is that what it looks like to you? What are the options for treatment? Do I need to treat at a certain time of year? Will it come back every year? Should I be concerned about the overall health of the tree? I included some pictures of the tree as well as the sap all over our trash bin.
Thank you so much!
Christina
Franklin County Ohio
Expert Response
You are correct, your tree is infected with magnolia scale. Below are two Factsheets with information and control recommendations.
https://bygl.osu.edu/node/1986
https://ohioline.osu.edu/factsheet/ENT-61
https://ohioline.osu.edu/factsheet/ENT-61
https://bygl.osu.edu/node/1986
https://ohioline.osu.edu/factsheet/ENT-61
https://ohioline.osu.edu/factsheet/ENT-61
Thank you! That is very helpful.
So is the best practice to wait until late August to treat? Or should I have someone out to treat it now, as soon as possible?
This tree is very large and adjacent to our house so I want to keep it healthy to avoid issues in the future.
Thank you,
Christina Boehm
Environmental Specialist II
<personal data hidden> Mobile
Pronouns: she/her/hers
On Jul 1, 2024, at 1:19 PM, Ask Extension <<personal data hidden>> wrote:
Yes, wait until August.
The first choice for insecticides should be those with a limited impact on beneficial insects, in this case the dormant oil sprays would be your best choice. Excerpts from the Fact Sheet listed above:
"Horticultural oils, often called summer oils, at the label rate applied after the crawlers have settled in late August can be very effective in reducing the scale population. Be sure to thoroughly wet down the stems and leaves. Dormant oils can be applied in October through November and again in March to kill the overwintering nymphs located on the stems. Be sure to check the spring buds, as some damage may be caused on the flower buds if they have begun to swell."
"The horticultural oils or “dormant” oils as they are often referred to, can and should be used as very effective control materials for insects that overwinter on the bark, under bark scales, in crevasses, etc. Once on the target pest, oil damages the membranes and the waxy layer of the exoskeleton resulting in suffocation. Timely application of oil will lead to fewer applications of miticides and insecticides later in the season. Oils fit well in IPM and resistance management programs. Toxicity is not a major issue since oil evaporates relatively quickly leaving very little residue.
The first choice for insecticides should be those with a limited impact on beneficial insects, in this case the dormant oil sprays would be your best choice. Excerpts from the Fact Sheet listed above:
"Horticultural oils, often called summer oils, at the label rate applied after the crawlers have settled in late August can be very effective in reducing the scale population. Be sure to thoroughly wet down the stems and leaves. Dormant oils can be applied in October through November and again in March to kill the overwintering nymphs located on the stems. Be sure to check the spring buds, as some damage may be caused on the flower buds if they have begun to swell."
"The horticultural oils or “dormant” oils as they are often referred to, can and should be used as very effective control materials for insects that overwinter on the bark, under bark scales, in crevasses, etc. Once on the target pest, oil damages the membranes and the waxy layer of the exoskeleton resulting in suffocation. Timely application of oil will lead to fewer applications of miticides and insecticides later in the season. Oils fit well in IPM and resistance management programs. Toxicity is not a major issue since oil evaporates relatively quickly leaving very little residue.
