Oozing sap (gummosis), which occurs in all trees to a greater or lesser extent, is caused by one or several of the following factors.
1. Natural tendency: Certain species of fruit trees, especially cherries, apricots, peaches, and plums, have a natural tendency to ooze sap. Small beads of sap often form on the bark of these trees.
2. Environmental stress: Trees that are under stress because they are growing in wet, poorly drained, or very dry soil may produce large quantities of sap, even though they are not diseased. Also, many fruit trees respond to rapid changes in weather conditions or soil moisture by gumming profusely.
3. Mechanical injury: Almost all trees ooze sap when the bark or wood is wounded. Wounding results from limb breakage; lawn-mower injury; pruning; improper staking, tying, or guying techniques; and other practices that damage the bark and wood.
4. Disease: Fruit trees respond to certain fungal and bacterial infections by forming cankers that gum profusely. Gummosis is often one of the initial signs of infection.
5. Insect damage: Several species of insects bore into tree bark, causing sap to ooze from the damaged areas. The larvae of certain beetles and moths are the most damaging types of boring insects. The tunnels they form in the wood often become infected with decay organisms.
The numbered solutions below correspond to the numbers in the analysis.
1. As long as the bark appears healthy, there is nothing to worry about.
2. If your tree is growing in wet, poorly drained soil, allow the soil to dry out between waterings. Provide for drainage of water away from tree trunks and roots. To help prevent crown rot, carefully remove enough soil around the base of the trunk to expose the first major roots.
3. Avoid unnecessary mechanical injuries to the tree. Stake, tie, and prune properly. For more information, see ORTHO's book All About Pruning. For instructions on staking and tying, see Staking and Guying, Canker Removal.
4. Remove badly infected branches and cut out cankers. For details about canker removal and treatment, see Staking and Guying, Canker Removal. Keep the tree healthy. For cultural information, look up your tree in the index.
5. Borers are difficult to control once they have burrowed into the wood. For instructions on borer control, see Bark Beetles and Borers.
