Gardening Questions And Answers
Common hackberries (Celtis occidentalis) in Illinois have this condition so frequently that we tend to think this symptom is part of the normal growth habit. Many of the twigs in a broom die back in the winter. These brooms are caused by a powdery mildew fungus in association with an eriophyid mite.
Known by the scientific name Pachypsylla celtidismamma as well as the more common “Hackberry nipplegall maker,” these tiny flying insects are not actually flies or gnats. They get their name from the Hackberry leaves they lay their eggs on. Eventually, a gall forms around the eggs and the developing larva.
Regular pruning is required for the hackberry tree, as weak growth may lead to branch breakage. Take pruning seriously whether your tree is young or mature, as the first 15 years of this tree’s life are quite formative in creating a sturdy structure. Prune during the dormant season to avoid creating accidental wounds.
Rooting Habit- Hackberry is a deep rooting species, ultimately reaching depths between 3 and 6 m (10 and 20 ft) on most sites (8). On clay prairie soil in North Dakota, however, the roots reached only to a depth of 1.4 m (4.5 ft); lateral extension was 12.6 m (41.5 ft). Strong taproots develop only […]
Hackberry’s somewhat inconspicuous flowers are pollinated by the wind, blooming at the same time that the leaves are beginning to emerge. Hackberries are monoecious; they have some flowers with just male reproductive parts, others with just female flowers, with both types of flowers on the same trees.
The sticky substance is called honeydew, and might be caused by a pest called the hackberry woolly aphid. As the aphids suck out plant juices, they excrete the sticky honeydew. Sometimes blackish sooty mold grows on the honeydew and creates a sticky mess on leaves and surfaces beneath infested trees.
Island chlorosis is a disease that appears on hackberry leaves as yellow spots. These are very blocky because they are delineated by veins. With green areas around the yellow spots, affected leaves appear as yellow islands in a sea of green, thus the name island chlorosis. Affected trees developed healthy new leaves.