Hello! We purchased a relatively mature Schubert Cherry from a nursery last year - for our anniversary - it was our "anniversi-tree" ;) - and it's been growing well despite having 4 feet of the top snap off during heavy winds last year (I had wire tied it to a stake right after and it has new growth on the section this year). Recently I noticed holes in 90% of the leaves. They don't appear to be in the brand new growth at the very top section, but pretty much everywhere else. Pictures attached - Help! What am I dealing with here?
May be fungal disease Coryneum Blight http://pnwhandbooks.org/plantdisease/cherry-flowering-prunus-spp-shothole-coryneum-blight
Thanks Sundrop, I thought it might be that as well. I researched Shothole and the following advice was provided for treatment: "Good sanitation is key to treating shot hole disease naturally. This is the surest way to keep the disease from coming back. All infected buds, blossoms, fruit, and twigs need to be promptly removed and destroyed. Contaminated leaves around and beneath the tree should be removed as well. Applying dormant spray — Bordeaux or fixed copper fungicide — in late fall is advisable..." So if I'm interpreting the above correctly I should remove the contaminated leaves ON the tree as well? That will strip about 90% of them... Should I not worry about the tree's ability to absorb sunlight without the leaves? Perhaps the 'fixed copper fungicide' is the better way to go?
My cherry (also peach and plum) trees all have some signs of Coryneum Blight; so I've been doing some research on the Web. One detailed article said that the spores spread primarily by being splashed by raindrops from infected areas to uninfected areas. Infected leaves on the ground or in the compost bin do not promote further infections. My trees would be denuded if I removed all of the infected leaves; so I have to rely on fungicide sprays for control. I've been unable to eliminate the disease by spraying so far, but my efforts have not been consistent. Because I have just retired, I should be able to follow a rigorous spray schedule this fall and next spring. The BC Department of Agriculture recommendations at http://www.agf.gov.bc.ca/cropprot/tfipm/coryneum.htm recommend spraying fixed copper in the fall before the rains start. Note that this is not a dormant spray, since all of our trees are still in full leaf at that time, typically September. Recommendations in Alberta might be different. Most sources also recommend another fungicide (not copper) spray at husk fall in spring.
