Elderberry blight

Asked May 18, 2020, 9:40 PM EDT

I have an elderberry bush/tree that is blooming this spring. Some of the tops of the branches have a sort of fungus on it, please see picture. I've been pinching those portions off and throwing them in the trash. Can you tell me what it is, and how to best treat it? Many thanks for your help!

Josephine County Oregon

1 Response

Part of the honeysuckle family, the elderberry (Sambucus spp.) is a deciduous shrub-like tree that produce edible berry-like fruits. Depending on the cultivar, elderberry (Sambucus spp.) can survive in U.S. Department of Agriculture hardiness zones 3 through 11. It's a relatively pest-resistant plant that thrives in well-drained soil and full sun or partial shade. In less-than-optimal conditions, sometimes elderberries can suffer from diseases like cankers, leaf and stem spots, and heart rots, as well as from pests like soft scales, borers and aphids. Elderberry shrubs can also be affected by nutritional deficiencies and excesses, as well as under- and over-watering.

Identify nitrogen and iron deficiencies in your elderberry plants by looking for stunted growth, yellowing leaves, and leaves, flowers and fruits that are undersized and develop later than normal.

Look for wilted foliage, leaf drop and leaf discoloration to diagnose under-watering. Identify over-watering problems by looking for root rots, unusually small leaves, as well as twig and limb dieback.

Drought, flooding and winter injury can leave elderberry plants open to canker-causing fungi. Botryosphaeria canker, Diaporthe stem canker and Nectria canker are among diseases that affect elderberry. Cankers appear on an elderberry as sunken wood or flesh on the trunk or stem. More obvious signs may include wilting or browning of leaves. Prune out infected branches as soon as you notice them to stop the disease' spread, and remove an entire plant if the canker reaches its trunk.

Other fungi may cause less serious leaf and stem spots. The spots may appear purple, brown or yellow, depending on the specific fungus. In some cases, they spread over enough of a leaf so that it falls off the plant. Remove from the area all infected material, including spotted branches, to stop the spread of the disease. Leaf and stem spot most often occur because of too much moisture on leaf and stem surfaces. So reduce overhead watering if possible. Remove and destroy all leaves before overwintering. Prune to promote better penetration of sunlight and air movement may help. Prune out infected twigs and branches may provide adequate control.

Hope this helps!