# What is wrong with this Hawthorne?



## Sapling (Jul 25, 2008)

I was hoping someone would know what this grey fungus/spore looking stuff is on this Hawthorne tree. I have attached a few photos......

Thanks for any input you might have. The lady who owns the tree has been told to remove it but I really don't think that is necessary. I want to help her determine what the problem and treat it appropriately so that she can continue to enjoy her tree.


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## 9th year rookie (Jul 25, 2008)

*Cedar Hawthorn Rust ???*

I don't know, but I would guess Cedar Hawthorn Rust.


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## pdqdl (Jul 25, 2008)

Cedar Hawthorn Rust is my guess too. 

Are you getting thickenings in the twigs, or just at the leaves ? I had a few hawthorns die from this 15 years ago. It completely blocked up the vascular system of the tree, and they rolled over dead in june/july, from a fruiting body issue in april/may.

It turns out that the variety of hawthorn that had been planted was particularly susceptible to cedar hawthorn rust.

I'm guessing as far north as you are, the season now is comparable to the Midwest several months ago. There is no treatment at this point except to try to avoid stress to the tree. Keep at optimum conditions for now, and hope your trees survive.

Next year, contact an arborist IN YOUR AREA who can advise you about the proper timing of preventative treatments.


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## Urban Forester (Jul 25, 2008)

There are 2 different rusts that have infected the tree. Hawthorn rust is on the leaves, cedar being the alternate, and juniper rust has infected the fruit. Somewhere in realitive close proximity to the tree is a juniper w/stems that have 3/4 long cankers on them. They open in the spring releasing the "spores" that infect the hawthorn fruit. This tree could be sprayed 2 to 3 times in the spring to reduce the amount of lesion formation. Neither of these diseases spread through the tree. They ONLY come from infected alternates. You will note tendriles on the spores of the leaves this is what will return to the cedar creating more "galls" that will open next spring and re-infect the hawthorn. The same goes for the "spikes" on the fruit. They return to the juniper increasing the stem cankers. Bayleton, 3336 (Thiophanate-Methyl) are both labeled for rust control and provide good results as long as the application timing is right.


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## ATH (Jul 26, 2008)

Once the disease gets going, it is hard to keep either the cedar and the hawthorn in good shape. (or hawthorn and juniper) (or cedar and apple in the case of ceder-apple rust). Note that these all look and behave similar but are different species...

That being the case, it you have control over both (they on the property you are managing, not the neighbor's) I usually suggest that you pick the one genus you like and get rid of the other. So if you have a beautiful and otherwise healthy hawthorn and some ugly out of control creeping juniper, take out the juniper and you will stop the cycle. On the other hand, if you have a nice eastern redcedar windbreak and a few stray "weedy" crabapples, take out the crabapples and you are in good shape.

Look up "Quince rust" for more info.


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## pdqdl (Jul 26, 2008)

There is no point [USUALLY] in trying to controlling the rust varieties by eliminating either of the host plants. The spores blow on the wind, and there is no protection from that.

If your junipers are the only ones for several miles, then your hawthorns might benefit from getting rid of the alternate host. The hawthorns that I lost many years ago were not any closer than 1/4 mile from the nearest juniper bush. It was a massive infection of twigs & leaves, 3 out of 5 of the trees died.


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