Having a flowering pomegranate tree (Punica granatum) in your garden virtually guarantees a constant stream of nectar-hungry butterflies and bees. When ants join the parade, however, they’re marching toward a different sort of food. Examine the tree’s twigs and young leaves, and you’ll find the sticky clear waste of several varieties of sap-sucking insects. Like preschoolers unskilled in the art of sharing, the ants defend their claim to this sugary goo against all comers.
Native to the Middle East -- and frequently associated with the apple tree in the Biblical story of the Garden of Eden -- pomegranate trees flourish where summers are hot and winters are mild in U.S. Department of Agriculture plant hardiness zones 7b through 11. The same conditions they relish, however, expose them to infestations of aphids, whiteflies, scales and mealybugs. These pests attach to a pomegranate’s leaves and twigs and drain sap with their beak-like, tissue-piercing mouths. A sure sign of their presence is sooty mold. Like ants, this fungus feeds on honeydew -- a sticky, sugary substance secreted by insects as they feed on sap. It may form leaf-blackening crusts thick enough to interfere with photosynthesis.
The Ant Problem
Your greatest allies in keeping these pests off your pomegranate tree are the beneficial insects that prey on them. Familiar beneficials include lady bugs, spiders and wasps. You're less likely to recognize lacewings and syrphid flies. They also wage war on the sapsuckers, until the ants decide to wage war on them. To increase honeydew production, the ants also transport the pests to uninfested branches. They may shelter aphids and mealybugs in their nests. Eliminating them is essential to maintaining a pest-free pomegranate tree.
Cultural Ant Control
If ants can't climb your pomegranate tree, they can't defend the honeydew producers from their predators. Pruning branches that touch the ground or an adjoining structure forces the ants to ascend the trunk. Wrapping the trunk with heavy, petroleum jelly-smeared paper traps them. Check the paper periodically and replace it as needed. Once you stop the stream of ants, the beneficial insects should return and manage the infestation.
For highly effective but low-toxicity ant control, set bait dispensers filled with liquid boric acid along the foraging trail between the ant nest and your tree. The ants carry the bait back to their nests, where it may take as long as a month to wipe out he queen and colony. By mixing pomegranate juice with the bait, you'll boost its chances of success. Make sure you place the dispensers where they won't tempt kids or pets.