Our 15’+ sunburst locust tree is covered in aphids and showing signs of yellowing, curling leaves on the tips. It had similar troubles last year with the same leaf symptoms. The tree was planted 3 years ago along with 3 other types. and is the only one not thriving. Now the aphids are spreading to other plants (i.e. potato vines in containers). Help! We have sprayed the tree with water but there seems to be more aphids and damage. Thanks so much.
This beautiful golden cultivar is, unfortunately, more prone to damage from pests such as aphids and honey locust plant bug than are honey locust cultivars with green leaves. The following web page’s advice, although specifically for honey locust plant bugs and leafhoppers, is also applicable to aphids: a strong jet of water from the hose, which you have already been doing. The application of insecticidal soap or neem oil is also an effective treatment that doesn’t damage beneficial insects or surrounding plants. Here is the fact sheet referred to above: https://learningstore.uwex.edu/Assets/pdfs/A3636.pdf
Your tree should show signs of new growth further into the summer. Although aphids are generally considered not to cause lasting damage to trees, repeated severe infestations could weaken your honey locust over time, so it is important to give your trees their best chance against insect pests by making sure that they are well watered during dry spells and mulched around their bases.