Noticed my hydrangeas has rust colored marks on the leaves. It was ok all summer but now it's starting to do this. It did it last year around this same time (before fall) then in the spring and summer they looked ok. I dont think its hurting the plants but was wondering........it doesnt look pretty.
"Rusty" hydrangeas
It sounds as if you have the synmptoms of Cercospora Leaf Spot, a fungal infection caused by Cercospora hydrangeae (a fungus). Scattered, small circular brown or purple spots first appear on leaves near the base of the plant and spreads upwards throught the plant canopy. These spots can eventually turns tan to light gray in color and may be surrounded by a brown or purple halo. The spots are usually about one-eighth to one-fourth inch in diameter. Spotting starts in mid summer and is most noticeable now in the fall. Once C. hydrangeae is introduced into a shrub, yearly outbreaks of this disease are likely to occur. You can apply fungicides to control it only; look for fungicides with these active ingredients: azoxystrobin (Heritage, has the longest repeat interval), chlorothalonil (Daconil), mancozeb (Dithane), myclobutanil (Immunox) and thiophanate-methyl (Cleary's 3336). Good sanitation techiniques can aid as well but nothing can cure it: remove dead stems and plant debris, do not overwater, do not water the leaves (water the soil instead or use drip irrigation). Many people actually do nothing when this happens because the plant usually develops symptoms close to the time when it goes dormant. I suggest you also dispose in the trash of the dried leaves/blooms that the plant produces in fall when it goes dormant; do not add them to the compost pile.
"Thanks for the info"
i'm wondering if it couldn't be spider mites. sometimes you can see webs.
Spider mites don't make rust colored marks on the leaves.
It would probably be best if you have a picture
I think Luis already identified the problem, the description fits exactly and that's something that hydrangeas are susceptible to.
If it were spider mites, the leaves would have a distinctive stippled yellow appearance.
I followed the suggestion to cut the rusty leaves off. They seem to be doing better continuing to put forth more growth.
Hello, Anaid. I am glad things are looking well. By the way, do not panic if the new foliage does not appear to grow as big as the spring foliage or if it suddendly does not look as nice. Once Fall arrives, plants begin to go dormant and that affects the way your new foliage looks. Depending on the variety of hydrangea, the leaves may change to stunning red/orange colors. Others change to yellows, browns etc.
The plants should go dormant after about two hard frosts; that is a general rule but not very useful for us in Texas because our temperatures fluctuate widely in winter. Here in Dallas/Ft.Worth, dormancy begins around November-December. You can expect dormancy later than that as your average temps do not get even into the 30s until the month of January. Leaf out occurs here in February-March.
To prepare the plants for dormancy, you can do a few things. Do not fertilize or prune after the month of July. And maintain 3-4" of mulch about 1' past the drip line. If Winter appears to be dry, water the plants once a week or once every two weeks.
Luis
the leaves iwll die & fall during the winter right? i just need to cover it w/mulch & it will come back in the spring?
The leaves will do that so you will be left with the stems poking out. They may "look" dry/dead but are simply dormant. These stems are the place where the plant will mostly leaf out again in February/March and from where it will mostly bloom out in May. I say 'mostly' because new stems tend to come of the crown/base of the plant every spring as well. So, yes, cover it with mulch at all times of the year. Three or four inches deep past the drip line. This helps maintain the soil moist and reduces the need for watering. It also protects the plant from temperature swings and windy days.
Luis, I have just gotten my first hydrangea. At the big Lowes sale! It didnt have a tag, but I decided to take the plunge. I dont know what variety it is. It was already past planting time. So it is indoors. It has the rusty leaf problem. The branches are losing more leaves. It does have new growth. Should I put it outside? We are getting a severe ice storm right now. I dont know how hardy it is. I watered it where the water could drain off, and it does look better. Should I mulch it, even indoors?
Lora:)
Hydrangeas are supposed to lose their leaves over the winter so that's nothing to worry about. Next year if you're careful not to splash water on the leaves when you're watering it hopefully the leaf spot problem won't come back. It's also important to pick up and throw away the spotted leaves that fall off because otherwise they'll leave fungal spores around to give you leaf spots again next year, but since you have this plant indoors I assume you're already doing that. I would definitely not put it outside--in your zone this is way too late in the year for planting. I'd keep it inside for the winter, then plant it in the spring.
Yes, do mulch inside too. I mulch with with one of my gardenias and makes the moisture stay longer.