Strawberry tree leaf spot, Arbutus leaves with black spots

Leaf spot on strawberry tree

Also known simply as spot anthracnose and black spot, this disease infects strawberry trees.

Symptoms are the presence of brown spots with a red or purple perimeter on leaves.

There are several strands of this disease, but all can be treated in the same manner.

This fungus will spread until all leaves are contaminated and drop off.

Strawberry tree leaf spot

Preventive care

Prevent leaf spotsThe most effective way to protect the tree is to give it an excellent growing environment.

  • Rich and very well-draining soil.
  • Regular fertilizing if the soil is very poor.
  • Regular watering over the first 2 years to make sure it settles in healthily.
  • Space around the tree for air to circulate and to avoid moist air around the tree.

At the end of winter, spray Bordeaux mixture 2 to 3 times, at a two-week interval.

Curative care

Black and yellow spots on a strawberry tree leaf, arbutus unedo.As soon as the fungus appears, collect fallen leaves, burn them or dispose of them in a place that won’t risk contaminating your plants.

There isn’t any natural product to use that can definitely eliminate this particular type of fungus, but you can reduce its spread with Bordeaux mix. Best of course is to remove any infected parts beforehand.

Using bordeaux mix and even fungus-killing fermented weed teas is better than to spray with mancozeb or myclobutanil based solutions, which are fungicides sold in horticulture stores.

What causes spots on strawberry tree leaves?

These three fungus spread most when the weather is warm.

  • Note: these fungus aren’t toxic to us humans. If ever your tree is infected, you can still harvest its berries to make arbutus berry jam without any risk at all.

1 – Spots are round, purple and spread on both leaves and twigs

You’re dealing with the more severe of these fungus, Elsinoë mattiroloanum.

It’s quite aggressive and must be taken care of quickly.

2 – Brown and purple spots, oblong shape

This is an infection by Ruptoseptoria unedonis.

It’s part of the family of septoria leaf spot fungi.

3 – Brown spots with reddish edges, roundish shape

This is a variant that is most common in British Columbia, in Canada.

Its name is Didymosporium arbuticola Zeller.

Read also

On the topic of strawberry trees:

Other diseases and treatments related to leaf spot:

Images: CC BY-NC 4.0: Josef Wirth, Laurentian Forestry Center: Al Funk, Public Domain: Luc Coekaerts