My red beauty plum orchard droped the plum

(Question)

I have 700 red beauty plum trees but the trees droped the plums.
The flower season went from 25th Feb to 15th March and these days the tempreture is from 5c’ to 15c’.   In the first 10 days,  80% flower drop and by the end of march, only 20% of small plums are remaining in the trees.   By the 10th April, 19% of the plums turned yellow and droped.  Now only 1% of the plums are remaining on the trees.  These trees are 12 years old.   I have only one kind of pollinators (mithly).   Please solve this problem.

(Answer)

I wonder where you are located?   We are the Toronto (Ontario, Canada) Master Gardeners and our fruit trees certainly don’t flower in February and March.

Since you have 700 trees, you must be in a commercial orchard business.  I would strongly recommend that you contact the appropriate government ministry, where you are, for advice – probably a Department of Agriculture or similar.  Here in Ontario, you would contact the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA).  Here is a link to their page on Plum Pox Virus, which can cause premature fruit drop: OMAFRA.  On that page you will see a description of the other symptoms of that disease.

But again, your best approach is to contact the agriculture department wherever your orchard is located, since there are many other reasons why your crops are failing to mature.