I'd be very reluctant to confirm a diagnosis of anthracnose without seeing photos. It is not all that common in typical home landscape settings although periods of wet, warm weather could certainly encourage it. I'd post a few photos that show clear indications of whatever malady they are suffering OR take samples into your local extension office.

Anthracnose is a pretty serious issue. After confirming an ID, I'd begin by removing all infected flowerheads and cleaning up any fallen leaves. Good garden sanitation is very important. And you can spray with a chlorothalonil-based fungicide, like Daconil.

Most anthracnose problems are pretty strictly plant-related.....dogwoods don't get oak anthracnose and hydrangeas don't get maple/sycamore anthracnose, etc., but azaleas DO share the same family of anthracnose fungi so I guess it is possible it could spread to the azaleas.

Thanks gardengal. I'm posting some pics here just in case.

It's starting to put out new leaves. I've picked off all of the spotted ones. Will spots develop on the new ones?

Thanks again.

Another pic.

Last one.

Hmmm... Thanks. Does that affect the blooms also? It seemed like all of the blooms turned brown very quickly.

I've read that anthracnose can't be cured... If it's leaf spot, can that eventually be eradicated? If I rip this one out and replace it next spring, will it be likely to be infected? I'm more optimistic about keeping it since I've seen the new growth, but not if this is going to happen every year.

Thanks for your help.

Cercospora is a common leaf spot on hydrangeas....it does not affect the health of the plant unless it is so bad that the leaves drop.....your hydrangea will be fine....it is just unsightly.....you must understand that every plant has its enemies, be it insects or disease.....some seasons are worse than others and you will find that some seasons you will not get cercospora on your hydrangeas....it depends on the weather and this leaf spot can come from a neighbour's plants via spores on the wind....so there is no magic solution......fungicides rarely prevent it and so it is best to keep the area around your plant free of infected leaves and try to live with the fact that gardening/nature is not perfect and it is fool hardy to try to fight it......best to live with it and enjoy yourself....

Well I can't say I'm not disappointed to hear that. Unsightly is a bit of an understatement. It went from blooming healthy and full to covered in spots, blackening, and looking half dead with all of the flowers turned brown in just a few days. It's never happened before. I guess its better than anthracnose. I'll see what it looks like in a few weeks. Thanks again.

This post was edited by sara82lee on Thu, Aug 8, 13 at 6:32

It is starting to be late in the growing season for applying fungicides and since they can be expensive, you may want to debate whether to apply them or not. Instead of fungicides, you can use good cleaning techniques such as: dispose in the trash all plant debris; replace the mulch if the infestation is large; do not water the blooms or the leaves; water the soil instead and do this early in the mornings; in the Fall, when the leaves have dried out, throw them and the blooms in the trash to prevent spreading the fungus; allow air currents to dry out the shrub when it gets wet by not planting other shrubs nearby; do not keep the mulch humid for long periods of time since this is beneficial to the fungi.

I agree the problem looks more like cercospora leaf spot than anthracnose but this is a common problem with hydrangeas, especially those grown in a nursery setting or those that may have received excessive overhead watering. Has it been rainier than usual? High humidity is also a big contributor.

Luis's suggestions are right on - avoid overhead watering, remove the most damaged of the foliage and clean up well, especially after the leaves fall in autumn. Sometimes a good mulch will help, as it smothers any fungal spores on the soil that may splash up and re-infect the plant.

This is not necessarily a recurring problem. Typically nursery grown plants that have the leaf spot lose it once they are planted in the home landscape. And in many cases, hydrangeas in the garden may experience the problem one season - if conditions are right - and not in the next.