What is causing the brown-black spots on my apricots?

Question

I've recently bought a house in the Auvergne region of France (South central) which is about 30 years old and that has the good fortune to have several mature fruit trees in the garden (cherry, apple, pear and apricot). All these species are in the same part of the garden so have similar aspects/exposures (lots of sun throughout the entire day) and presumably similar soil and drainage.

However, whilst my cherry crop was fine and I can see no problems with the other fruits still on the tree, most of my apricots have these kind of black-brown spots all over them:

Though the spots don't seem to make any difference to the flavour of the fruit and the texture is unchanged apart from the skin being slightly harder where the spots are. What may be different is that I've noticed that the affected fruit tend to be more prone to rotting on the tree, and many of the fruit that have fallen from the tree are mouldy.

Any suggestions to what might be causing this and how I may eliminate the problem in future years?

Answer 1

What you have is a fungal disease known as Coryneum blight. From here:

Coryneum blight, also known as shothole blight, is a fungal disease that can cause damage on peach, nectarine, apricot, almonds (ornamental as well as nut bearing) and, to a lesser degree, cherries (tart and sweet). Coryneus blight is caused by the fungal pathogen Wilsonomyces carpophilus.

Here are the control methods listed by the University of California:

Prune and dispose of infected tissue as soon as it appears. After leaf drop, inspect plants carefully and prune infected buds and twigs with lesions. Diligent sanitation and water management can provide adequate control where the incidence of shot hole is low. Avoid overhead sprinklers or use a low angle to avoid wetting foliage. Also, some varieties may be less susceptible. Where disease incidence is high, fungicides such as Bordeaux mixtures or fixed coppers may be applied. On peaches and nectarines, a dormant spray of copper in late fall will work well. On almonds, spray fungicides at petal fall in the spring.