Water, Feed, & Prune
In the first year or two after being planted, plum trees require regular watering. In early spring, and again in midsummer, feed trees with 10-10-10 fertilizer. Maintain a weedand grass-free zone of about 3' in diameter around the base of a tree. Prune any suckers that sprout from the base of the tree and any waterspouts that shoot up from branches.
Pruning Pyramid Trees
Prune in June to avoid the risk of silver leaf disease. The stem should be cut back to approximately 60cm (2 ft.) above soil level. Make the cut (point A) just above a bud. Remove (rub out) the bud (at point B) below the top bud, making sure that there at least three or four buds remaining below.
Prune in June to avoid the risk of silver leaf disease. In the second year's pruning, cut back the main stem by about 45cm (18 in), just above a bud (point A). Below this cut, there should be three or four buds above the branches from last year.
Prune all the remaining branches so that they are about 25cm (10in) long. The cut should be immediately above a healthy looking bud.
Prune in June to avoid the risk of silver leaf disease. In the third year's pruning, again cut back the main stem by about 45cm (18 in), just above a bud (point A). Below this cut, there should be three or four buds above the branches from last year.
Prune the branches which have grown this year so that they are about 25cm (10in) long (points B). The cut should be immediately above a healthy looking bud.
Established plum trees should be pruned in June and the pruning is restricted to new growth not bearing fruit this year. The aim is to keep the tree size within the available space. Pinch out strong-growing side shoots (grown this year) to 6 leaves from their parent branch - this will encourage fruit next year. When the central stem gets to about 2.5 m (8ft) high, prune it back into old wood, 1m (3ft) above the highest branch. Whilst pruning this new growth, look for any dead wood, prune this out and burn it.
Insects & Disease
Always read chemical labels and follow manufacturer’s directions carefully to avoid injury to your tree, the environment or yourself.
Plums are susceptible to mold growth on fruit due to lack of air movement and wet springs. Remove any dead limbs and rake up any leaf debris. In early spring, spray with #1 Dormant Oil to suffocate any insects or eggs in the bark, this spray also helps control black knot. To control brown rot, spray with #2 Daconil or Fungonil just before blooms open and when 90% of the blossoms are open. After petal fall, spray with #3 Orchard Spray, and repeat every 10-14 days. Stop 1 week before harvest. Apply one last #1 Dormant Oil spray to the tree in late fall after most leaves have dropped.
Never spray pesticides when trees are in bloom as this will kill the pollinating honeybees.
Always spray when the temperature is above freezing and there is no wind. Early in the morning is best.
Good sanitation practices are necessary to control pest problems. Cut out all dead or diseased wood and disinfect pruning tools with a household disinfectant (Lysol or bleach). Pick up all fruit that has fallen to reduce insects.
Protect From Late Frost
Plum blossoms must be protected from spring frost damage, which can wipe out a year’s crop. If frost is predicted after fruit-bud set, place lightweight fabric over the tree to form a tent.
Some plum trees must be thinned in order to produce a decent crop of fruit and to prevent branches from breaking due to excessive weight. When the fruits are about the size of a penny, remove enough so that no two plums are closer than 5". Remove the smallest fruit and keep the larger ones.