Tom from United States writes
I have treated a large hackberry tree (trunk circumference about 100 inches) with a gallon of Fertilome tree and shrub insect drench last June and then again late this March. The leaves are once again showing the small pods of the nipple gaul on the back of the leaf. Am I using enough of the product ? Should I treat it again this spring? I do not want to damage the tree but the infestation is rather troublesome since it caused significant early leaf dropping as early as mid July into August. By early Sept the tree is almost bare. Any help you can provide would be appreciated.
You would need to use 1 oz. of Fertilome Tree and Shrub Systemic per inch of trunk circumference mixed with at least 10 gallons of water and poured around the base of the tree trunk. It is best to keep the treated area moist for the first 7 days following the application. Treating Hackberry Gall Psyllid with a systemic insecticide to kill psyllids when they feed would be ideal, but this approach means planning ahead because systemics take a few weeks to translocate through the vein system. During the summer, psyllids are protected inside the gall from insecticides sprayed on the leaves so foliar treatments won't be effective then. For best results you would need to treat trees in the spring to kill newly hatched nymphs before the onset of gall formation and again in the fall while treating an active infestation. Repeat annual applications once control is gained is highly recommended as a preventative.
Answer last updated on: 05/29/2014