White growths on tree

Asked August 2, 2019, 8:44 PM EDT

My parents magnolia tree has these white growths on them. Can you tell me if it’s a fungus and if it’s treatable please?

Lapeer County Michigan magnolia scale

2 Responses

Hello,

This is an insect called magnolia scale. The large bumps are the mother scales and the “babies” are underneath, protected from chemicals. When these emerge they crawl around to find a feeding spot, and they are called “crawlers.” The crawler stage is the best time to treat with chemicals.

For small areas of Magnolia Scale infestation, pruning and destoying branches, or rubbing off the scales by hand can be done right now (July). For medium to large amounts of scale, chemicals can be used when the crawlers hatch. A soil drench would take too long to reach the scale insects if applied now.

To remove by hand, use gloves and a plastic kitchen scrubby or brush, or your thumb nail. Be careful to not damage the bark of the tree. If you decide to use spray treatments for control, select a product that contains bifenthrin, carbaryl, cyflulthrin, horticultural oil, insecticidal soap, malathion, or permethrin.

Proper timing of the application of chemicals is critical. Apply spray treatments when Enviroweather maps show Growing degree days of 1925-1950. This is usually in late August or early September. Hot years this timing is earlier. Apply a second treatment 10 to 14 days after the first.

An accurate way to tell when crawlers hatch is monitoring the Growing Degree Days (GDD) for the weather station nearest your tree. GDD 1925-1950 is when crawlers hatch.

Here in central Michigan for Aug. 2 the GDD is 1626 So, you have some time to get your insecticide ready if you need it, and you have some days to remove scales.

To monitor GDD use the Extension Enviroweather tool. Choose a weather station close to your location, such as Flint. Then click the “Get Report” button on the left of the screen.

https://enviroweather.msu.edu/run.php?stn=flt&mod=w_ddm&da1=30&mo1=7&da2=2&mo2=8&yr=2019&mc=67&ds=cd

Here are treatment details -

http://idl.entomology.cornell.edu/wp-content/uploads/Magnolia-Scale.pdf

https://hort.extension.wisc.edu/articles/magnolia-scale/

Persistence and timing are key to control. Remember to monitor your tree each season. Thanks for using our service.

I forgot to include information about your last picture, which shows a couple different things.

The substance on the trunk is lichen. They are harmless to the tree.

Here is more information- https://njaes.rutgers.edu/fs1205/

The trunk is starting to crack, and the roots are buried too deep in the soil. These symptoms of stress are not good for the tree. Making a larger circle of mulch around the tree, at least 8 feet in diameter , or more, with turf removed would help. Mulch this circle but do not let mulch touch the trunk. Mulch should be 3-4 inches deep, no deeper. Water the tree during droughts, even in fall when it is dry.

A certified arborist could be hired to evaluate the tree and correctly aerate the root zone and excavate the root collar, if possible. He could also treat the tree for the scale insects if you do not want to do it yourself. Correcting these things will extend the life of the tree.

A certified arborist is a professional who has taken training in care, diseases, pests and passed certification tests. He/she will come on site and give a complete diagnosis and a plant care plan. Find certified arborists by zip code here—-

www.treesaregood.org