Fruit trees rely on stored nutrients for flowering, initial root growth, and fruit set in spring (this nutrition was provided by the microbes in the soil, and any compost or fertiliser you added last autumn). As they move into spring, the stored nutrient runs out, and as soon as the tree’s roots are well established, they’ll be looking for more nutrients from the soil. Your job, at this time of the year, is to wake up and revitalise your soil microbes so they can start doing their important job of feeding your fruit trees, and to make sure there is enough supplementary nutrient in the soil by adding some organic fertiliser and/or compost.
Read the article in Spring – Week 3.