Question
Hello Dr Vann,
Our crab apple tree came with the house. We were told - it flowers every other year. the 2 springs we were here - it flowered every year. Last year we noticed the blossoms were very reduced. The leaves turned reddish, developed black spots and fell in droves. The local Home Depot advised us to use Dormant. Early this spring we applied Dormant spray - to the best of our ability (its a tall 10-12 feet tree - so cant say we reached all the branches). However, the tree had reduced flowers. The lower 2 branches - have no leaves at all. After the flowers fell off - I applied Dormant again. But the leaf cover is pretty limited. Already on the lower branches I can see rust colored spots.
What am I doing wrong? What should I do? Please help.

Farah

Answer
Hi Farah:

Difficult to say w/o someone actually seeing the tree and foliage. Crabapple is susceptible to several diseases of the leaves- one of which is called "scab".  It is very important to determine exactly what the cause of the problem is before taking corrective measures.  Lets take a look at some pictures first.  Do a search using "Google Images" on your computer, type in "scab of crabapple" and take a look at some of the images to see if it matches your spots on the leaves.  Scab is caused by a fungus that causes the leaves to drop early.  If it is scab, it will be best to spray your tree for the first time as soon as the leaves start forming out of the bud in the Spring.  By starting now, I would not expect a lot of control. Also, if it is scab, it is very helpful to rake up and destroy (burn, if possible)all of those fallen leaves during the winter- just BEFORE the spring gets here and buds start to swell.This fungus can "spend the winter" on those dead leaves and these leaves can be a source for the problem next season.

Consider getting a soil test done if you can.  Keep it watered and fertilized properly to promote vigor.

If it is scab, there are better products than dormant oil. Such examples include: Bonide Infuse or HI-Yield Captan.  Check with your local garden center, not the big box stores.  You can also carry in a few leaves to them for their opinion also.

P.S. If it turns out to be scab and you intend to spray, keep in mind that you will need to have a good enough sprayer to allow you to cover the ENTIRE tree.  Both correct timing and coverage are important.  Be sure to read the label on these spray materials throughly for instructions on mixing and spraying.

Regards
Steve