The Health and Safety advice and guidance offered is intended for general . five portions of fruit and vegetables a day has been emphasised for some time. .. Pruning fruit trees and bushes can seem a daunting prospect, but if you follow a. As fruit trees mature, they must undergo two pruning phases. you remove leaves which would otherwise generate food for the tree and thus, vegetative growth. Learning» · Courses & Workshops · Bursaries · Schools and Children · RHS Libraries As long as fruit trees are producing a reasonable harvest of tasty fruit, they Main causes Various, including poor pollination, over-pruning, lack of water As winter food becomes scarce, birds will eat buds of cherries, plums and pears.