There is a process called a June drop of small fruitlets that are discarded by a fruit tree. Even in the ground my limited root stock pears and apples drop a lot of fruitlets. I am always on patrol for pests. Pear mites turn tiny pears black. Aphids on mature trees, I clip off the affected leaves. Orange blobs on pear leaves I take the leaf off. Tent caterpillars I clip the tent out and exterminate. Make sure your container fruits are fed and watered and potted on regularly. If you have correct pollinators, and are lucky with the vigour of your trees, and the weather, you will get a crop. Try not too let small trees bear too much fruit, however tempting this may be. Not more than 3 per spur. Good Luck.....Slipfel