Apple Scab, something else, or nothing at all?

AdkEric

Branched out member
Location
Adirondacks
A friend of the family requested I take a look at her flowering crabapple today. Most, but not all, of the remaining foliage has discoloration seen on the pictured leaves.

I rarely deal with any sort of apples so I'm a bit out of my element. I unfortunately didn't take a picture of the entire tree.

It is mature, no cankers or fruiting bodies, and she claims it had dense foliage until mid summer and flowered nicely. The fruit didn't appear to have any lesions or markings on it. No recent trauma to the tree or roots. Not too much dead wood present.

It has been hot and dry for several weeks. Foliage is thin and mostly present in the upper canopy and tips of branches. The leaves on the ground are yellow, and don't appear crunchy and shriveled up as they might from fire blight. She has a few pear trees, lilacs, and a couple maples that seem fine.

Any thoughts would be appreciated. I'm obviously not in the malus business, nor am I much of a pest/disease stud. It's unlikely I'll perform any required work, but I'd like to steer her in the right direction.
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Very interesting.

Looks like Apple Scab, as well as something Bacterial (water soaked) and would love to see it under the microscope to look closer.

The marginal necrosis too is curious.....secondary issue perhaps from the mentioned hot and dry period, late in the season.

How is your local cooperative extension to get some conformation?

Good fall leaf cleanup before the 1st snowfall won't hurt either, looking towards a better 2025.
 
Our Malus (and everything else) have been really drought stressed the last number of yeears (on top of that we had watering bans this summer). I've been giving our deciduous trees Arborjet NutriRoot (from Treestuff) in the spring after snowmelt and spring rains and they've come back really well. Maybe worth a try. But don't fertilize during the drought times.

Addenda: Have used Bordeaux (copper) foliar spray too in years past - so so results if it's bacterial maybe. Also deadwooding/ pruning can be your friend to allow air and sun to get to everything, esp. if it's wet/ cool. I "sanitize" all the pruning tools with Isopropanol before and after pruning too - maybe over the top a bit but makes me feel like I've been fastidious.
 
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Thanks everyone for the insight. It is appreciated.

We did have a wet, humid spring and early summer.

I've reached out to my local coop extension (Cornell) but it was after hours yesterday and they're closed on Friday. We'll see what Monday brings.
 

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