Mountain Ash leaves scorching?

[Greenleaf]

I have a customer who has a Cotoneaster displaying signs of fireblight (die-back of branches with scorched black appearnance and crooked tips) and in the same yard are 2 mountain ash (Sorbus americana) with scorched leaves. I automaticaly assumed that the Mountain Ash might have fireblight aswell. Not sure, maybe an abiotic disorder such as drought or frost?

Any insight would be much appreciated....picture attatched. Thanks.

 

[ADDA]

Drought, herbicides.........road salt???? Could be a number of things although drought most likely due to extent of necrosis and lack of yellowing to the leaves.

 

[Urban Forester]

With no "crooking" visable on the terminal, I doubt it's fireblight. It appears to be the most common "disease" of Mtn. Ash, leaf scorch.

 

[Ed Roland]

Fireblight (erwinia) is proprietary to the family roseacea. Pear, apple, hawthorne, even cotoneaster get fireblight. Not ash.

More likely culprits for the ash disorder would be bacterial leaf scorch or possibly discula anthracnose. These trees getting enough water?

 

[Urban Forester]

Fireblight (erwinia) is proprietary to the family roseacea. Pear, apple, hawthorne, even cotoneaster get fireblight. Not ash.
?

Sorbus Americana (Mtn. Ash) IS in the family roseacea, not Oleaceae
therefore is suseptiple to fireblight. I have dealt with at least 12 in 20 years that have/had fire blight.

 

[Ed Roland]

UF, nice call.
I was running on the assumption this was a true ash in the olive family Oleaceae.