My hydrangeas are dying

(Question)

The hydrangeas that were planted last September have tiny black bugs on them, the buds are not opening up and are curling up and drying and there are some small uneven holes on some of the leaves as well as some small brown spots. Is this a fungus, what pests have invaded the plants and is it a watering problem? Please help. Thank you. Myra

(Answer)

Sorry to hear that your hydrangeas planted just last fall are having problems.  The small black bugs you mention could be aphids which are a common problem for hydrangeas.  In small numbers they don’t do a lot of damage but a high population can cause distortion and yellowing of the leaves.  Aphids typically hang out on the underside of the leaves.  You can control aphids by washing them off with a strong spray of water or with an application of insecticidal soap – available at your local garden centre.

Aphids don’t account for all of the symptoms you are observing. The small, brown spots may indicate the presence of a leaf spot disease which is a fungal infection.  Our very rainy spring may be contributing to this disease.  Overhead watering can also promote leaf spots.  Water at the ground level or early in the day so the foliage can dry off before night. Dispose of any infected leaves as they drop to reduce the spread of infection.

You haven’t mentioned the type of hydrangea you are growing. Hydrangea macrophylla which has large, round pink or blue blooms in the summer is particularly prone to winter damage. Our cold winter and late spring could account for the buds not opening.

One or more of these suggestions may account for the problems you are seeing – or not.  I’ve focused on the symptoms you described.  I’ve included a link below to a good article on the pests and diseases to which hydrangea are prone. Continue to follow good maintenance practices to ensure your plants are healthy. Healthy plants can tolerate the loss of some leaves and are not adversely affected by minor damage from pests. In addition to the instructions above on watering, water thoroughly and infrequently to promote deep growth of the roots.  Avoid over fertilization.  Tender new growth is the most susceptible to attack by pests and diseases.  Overuse of nitrogen can cause an abundance of new growth.

You are obviously concerned that your hydrangeas are dying. Some of my suggestions may help. However, as these are first year plants, I suggest you take a sample of the diseased leaves and black bugs along with photos of your plant to the supplier of your plants for an accurate diagnosis and what, if any, remedial action to take.  They will be keen to ensure that plant material they have supplied does survive and thrive.

Good luck with your hydrangeas!

http://www.ladybug.uconn.edu/FactSheets/hydrangea-diseasesand-pests.php