Agri-Fos For Sweetgum Root Rot Really The Best Answer Here?

Question

Just started in PHC work and am taking over a new client’s landscaping property. There is a circle of slender silhouette colimner sweetgum in the back yard in a mulch bed. The previous treatment recommend from their previous PHC specialist was Agri-Fos for root rot. But as far as I understand this variety of Sweetgum tend to be relatively resistant to fungal root disorders, and borer pests. It is in semi-clay soil, and not under shade. They have fissures that look kind of like winter damage, and the one has that old wound that doesn’t look great. The pictures were taken 5/11/21 with a lower than average GDD 145 BASE 50, right after the last freeze warning for the year. There are Magnolias growing very close by, in the same conditions, that are doing very well. Scale didn’t even need to be treated this year, they look so good. Surrounding boxwoods look great too. Not sure if the Agri-Fos is a upsell from the last PHC company, or if I am missing the underlying signs of disease/pest. Hope you can give me some insight. Thanks!

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Answer 1

Although they can be resistant to borers and miners, this does not make it immune to them. Unfortunately, I do see signs of previous issues with them. It could be that the damage has left a bacterial infection. It does look like one that has progressed.

Technically the treatment should work for that, to some degree, but it will return if the soil conditions are not within the correct parameters.

Be sure to test the soil for pH imbalances and nutrient deficiencies. Many times, all it takes is a little nutrients to help a tree recover from bacterial issues.

These articles will help:

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/soil-ph-plants.htm

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm

Clay soils will tend to have issues with nutrient deficiencies and higher pH. The tests will show you where the soil is and where it needs to be.

Here is an article that will offer more tips on the care of the tree:

https://www.gardeningknowhow.com/ornamental/trees/sweetgum/sweetgum-tree-info.htm