It’s a really good idea to keep the base of fruit trees mulched at all times with well rotted organic matter or similar product. Ensure the ground underneath is damp (water if necessary) before placing the mulch around the tree.
Take care to keep a gap between the main trunk and the mulch, because this allows air to circulate whilst keeping moisture in the ground and weeds at bay. Make sure to regularly check the mulch, as worms will pull a lot of the organic matter down into the soil. You may need to top up the mulch from time to time.
If you haven’t already done so, summer prune the trees by cutting away new growth just above a bud. This encourages the tree to fruit more heavily the following year. But try to avoid cutting into old wood as you may be cutting away fruiting buds.