Spots On Hydrangea Leaves – How To Treat Hydrangeas With Leaf Spots

Spots On Hydrangea Leaves – How To Treat Hydrangeas With Leaf Spots

By: Becca Badgett, Co-author of How to Grow an EMERGENCY Garden

Hydrangeas are afavorite flowering shrub of many, with big blooms and attractive foliage.However, spots on hydrangea leaves can ruin the beauty and infect other shrubs too.Learn how to treat the hydrangea leaf spot disease and make your plantbeautiful again.

Leaf Spot Diseases on Hydrangeas

Leaf spotting on hydrangea ismostly caused by the fungus Cercospora and affects most of this family ofplants. It is common from summer through fall. The fungus exists in the soiland is moved onto the plant by overhead watering or rain.

Plants are usually infected a monthor two before spots appear on the leaves. Symptoms worsen during summers withheavy rainfall. Plants may flower less, with smaller blooms, and are lessvigorous overall. Hydrangeas with leaf spots rarely die from the disease, butthey can decline and defoliate early.

The spots first occur on lower,older leaves and then move upward. Circular shaped spots are small and purple,increasing to irregular patches with a grayish-tan center bordered by purple orbrown. At later stages, leaf spots begin yellowing. Remove damaged leaves atany point and dispose of them. They can hold the fungus over winter, so getthem out of the area.

Bacterial leaf spots caused by Xanthomonascan also occur, particularly on oakleaf hydrangea plants. Moist conditionspromote spread, with reddish-purple spots that look more angular in appearance.

Treating Hydrangea Leaf Spot

Treating already damaged leavesthat are going to fall off is not the solution to avoiding leaf spot next year.Practice good sanitation by disposing of all damaged leaves as they fall. Inspring, avoid overhead watering, if possible. The water can splash the fungusfrom leaf to leaf and onto other plants nearby.

If the plants are valuable to youand you want to put in the work, you may attempt a prevention program in springas new leaves emerge. Spray new leaves with fungicide every 10 to 14 days onbushes that showed damage last year. Spray new leaves as they appear on theplant and as they develop. Spray the stems and limbs and remember to get theleaf underside. Fungicideapplication on a regular basis may get rid of leaf spot if yourissue was severe.

Applications of copper-basedfungicides in late spring can be used to help limit the spreadof bacterial infections but will not cure the plant.

If you’re just planting hydrangeasin your landscape, choose those that are disease resistant to help avoid thisand other issues. Check with the nursery to make sure you’re buying adisease-resistant plant. Avoid overhead watering.

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Primarily a problem on new growth, aphids can be dislodged by spraying your plants with a strong blast of water from the hose. (Be careful not to damage the hydrangea itself.) If they return, try an insecticidal soap or spray. Not sure if your pests are aphids? If you see ants on your hydrangea leaves, small, green aphids are probably around. They like to feed on a sticky substance, honeydew, produced by the ants.

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This beautiful flowering shrub can add color and abundance to your garden.

Root Rot

Climbing hydrangea's roots cannot tolerate standing water. If your hydrangea is not planted in well-drained soil, its roots are susceptible to the fungus that causes root rot. Affected plants will suddenly wilt and will not perk up when watered. Once a plant is afflicted with root rot, it will die within a few weeks. As soon as you identify your plant's disease as root rot, uproot and destroy it.

Root rust is another climbing hydrangea fungus. It manifests in small, rust-colored spots on the underside of climbing hydrangea's leaves. When touched, the fungus will rub off onto your hands and disperse, spreading to other areas of your climbing hydrangea or neighboring plants. To rid your plant of root rust, remove any affected leaves or leaf litter as soon as the rust spots are sighted. If the disease comes back the following year, spray the plant with a fungicide according to the manufacturer's instructions.

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