To understand when to spray insecticides and fertilisers on apple trees, you need to know the various growth stages of an apple tree, which serve as time points for various applications. These stages are not standardised measurements within horticulture but they do define different time points in most fruit trees.
During dormancy, the apple tree is resting and almost all growth is on hold. Very little sap remains in the branches and the cold weather does not affect the tree.
Silver Tip occurs when the tip of the bud opens slightly in the centre to reveal a little silver tissue from new growth inside. This signals that the tree is no longer dormant.
As the bud continues to swell, the tip of the bud changes in appearance from a little sliver of silver showing to green material. At this stage, you know the bud is close to opening.
In this stage, the ends of the apple tree branches now have 1/2-inch of green growth sticking out, somewhat bunched up.
The green growth from the previous stage unfurls into a whorl of small leaves and a tight cluster of blossom buds is visible in the centre of the leaves.
As the blossom buds in the centre of the leaf whorls swell, their housing opens slightly to reveal a little of the pink blossom tissue inside.
As the name implies, at this stage the apple tree is in full bloom. All the leaf whorls are holding out green leaves with clusters of five-pedaled pink flowers in their centre.
When the pollination period of the flowers on the apple tree passes, the blossoms wilt slightly and fall to the ground. They tend to coat the ground under the trees like a covering of snow.
This is the stage in the growing season of the apple tree when the pollinated flowers that have set fruit are clearly visible and the unfertilised fruits drop to the ground. From here on, the energy of the apple tree goes to producing leaves to support ripening of the fruit.