Cherry leaf spot
I recently bought a home in Alto and we have several fruit trees in our yard (pear, apples and tart cherries). We got a great crop of tart cherries this year but recently, the 2 cherry trees lost almost all of their leaves. I've been looking online and I suspect it's cherry leaf spot. I need some advice on how to treat it. I would like to try something organic first before I resort to fungicides.
I've never had fruit trees before so I'm a complete novice.
Thanks for any help you can provide.
Kent County Michigan
Cheery leaf spot is a hard disease to control. The fungus attacks the leaves through the stomates of the leaves, so the leaves must be protected all season long. The organic control is the use of copper. Copper is phytotoxic to many plants and you should not use it on sweet cherries as it will take the leaves off
Here are some links to cherry leafspot.
Here is a basic overview of the disease
Here is a very good review of the disease and control from Ohio State
Ideally you would apply the copper before rains to prevent infection. Copper applied immediately after a rain helps but you will still get the disease. Most commercial growers apply sprays every 7 to 10 days as the new leaves emerge to protect them. Once shoot growth stops you still need to apply copper but the interval is increased to about 14 days. If you have long dry spells with no rain you can stop applying copper until rain is in the forecast again. This prevents the buildup of copper on the leaves and loss of the leaves due to copper phytotoxicity.
Here are two links to controlling cherry leaf spot with funigicides which also include discussions of copper.
Thanks for the information. How do I know when shoot growth stops? Can you apply copper when the tart cherries are still on the tree? How careful do I have to be about preventing the copper from getting on the nearby apple and pear trees?
Shoot growth stops when the shoot stops putting out new leaves. You will not see any small leaves at the shoot tip only large fully grown leaves. This usually occurs in mid to late June as the fruit begins to color. Yes you can apply to the fruit. A little over spray on pears or apples will not harm them.