We would normally defer to arborists who have assessed the tree in person, especially since they can see the condition of the canopy as it can be a decent indicator of overall tree health. However, since you received differing diagnoses, our thoughts are that the tree should get air-spaded to inspect the root collar and probably no fungicides as they are preventative measures only, not curative. Were these individuals certified arborists, or just tree company workers? Credentialed persons are trained and keep up-to-date with new developments in tree care science and best practices; some work as members of a tree-care company while others work independently. You can find certified arborists though this search tool, if needed: https://www.treesaregood.org/findanarborist/arboristsearch

To be fair to the arborists, it can be challenging to diagnose tree ailments since often an array of factors can lead to similar symptoms. Chronic stress takes its toll on trees in suburban conditions, and symptoms may not manifest for months or even years. Sometimes, environmental stress causes sap oozing or leaf loss that might otherwise be attributed to pests or disease. Root system issues often lead to canopy dieback, and some, if caught early, can be corrected to prevent further decline. Phytophthora is a fungus-like organism which can infect plant roots that are kept too wet (or are sited in poor drainage); its damage isn't directly reversible and treatments are questionable if the core issue of soil drainage can't be addressed. Cankers (tissue infections, usually of trunk or branch wood and usually resulting in discoloration or oozing) can be caused by an array of pathogens, and wood-boring insects can also cause sap leaking and resulting discoloration on bark. Both cankers and borers tend to target trees already under stress. "Wet wood" is another disorder which causes bark discoloration but has no cure: https://extension.umd.edu/resource/tree-trunks-wet-wood-or-slime-flux

The tree does not appear to have a visible root flare. This is the point where roots begin to branch off of the trunk, and should sit just at or barely under the soil surface. When tree trunks don't seem to widen noticeably at their base, a buried root flare is likely. This condition promotes (or hides) girdling roots, which can slowly "strangle" the trunk. Air-spading by a tree-care company uses compressed air to gently blast away surface soil to expose th flare or "root collar" (without injuring roots by digging) so it can be examined and any circling roots cut, if possible.
https://extension.umd.edu/resource/girdling-roots

Miri

Well, "not curative" in the sense that wounds and existing tissue damage in plants does not heal in the same way they would for people. The spread of a pathogen or pest might be halted by treatments, but mainly by a tree's own internal defenses, which include a process called compartmentalization. Essentially, they can wall-off access to healthy tissues by creating areas of dead, fortified cells surrounding compromised wood. Although wound closure (more of a sealing-over than mending back together) can take years, eventually trees can outgrow the original damage if those processes are successful.

Yes, in general, just keep monitoring the tree for changing symptoms or canopy decline in future growing seasons. Red Maple appreciate moist soils and may see a reduction in overall stress if irrigated periodically (as needed) during summer or autumn when rain is lacking.
https://extension.umd.edu/resource/watering-trees-and-shrubs

Miri

You're welcome.

Alan - We are not located at the Montgomery County Extension Office. To check the status of the plant samples you dropped off there, I recommend that you contact Linda Waters or Cathy Yingling. Their contact information is provided on this page of their website. https://extension.umd.edu/locations/montgomery-county/contact

Christa

Yes, you can drop off plant samples for Steve Dubik at the Montgomery County Extension Office, 18410 Muncaster Rd, Derwood. It would be best to contact Linda Waters or Cathy Yingling there to find out what their process is for reviewing samples that are submitted. The phone number is <personal data hidden>.

The HGIC office is located in Ellicott City and we do not accept plant or insect samples at our location. You are welcome to send us photos of the plants in question (you can attach them here) and we can take a look at them that way.

Christa