I have a plum tree
1) the fruits is falling off the tree
2) the leafs are having a holes
Thank you for contacting the Toronto Master Gardeners.
Your questions is one we have answered before so I’m attaching a link to a previous question & answer which should give you all the guidance you need, see below:
It is difficult for me to see the holes in your leaves from your photograph. Have you inspected the plant for insects? Without a picture of the damage it is difficult for me to try an assess what could be the cause of the damage. There are several aphid species which attack plum trees. Check the underside of your leaves for these leaf sucking insects. If you see any sign of these insects you can wash aphids from plants with a strong stream of water or by hand-wiping. Aphid populations tend to be higher in plants that are fertilized liberally with nitrogen. Avoid excessive watering which, together with nitrogen applications, produces flushes of succulent growth.
The holes in your leaves could be shot hole disease. This is caused by a fungus. According to the University of California Integrated Pest Management : “Shot hole first appears in the spring as purplish or reddish spots about 1/10 inch in diameter on new buds, leaves, and shoots. Spots on young leaves commonly have a narrow, light green or yellow margin. The spots expand and their centers turn brown and can drop out, leaving holes.”
The foliage and fruit of many plum, peach and apricot varieties is susceptible to infection by bacterial leaf spot, Xanthomonas arboricola, that causes small yellow spots and a shot-hole appearance in foliage.
The following links shows you various images for each disease so that you can narrow down what coiuld be the possible cause of what you are seeing: