Plant Doctor Archive

 MY feijoa tree, now almost 3 years old, seems to be suffering. The leaves are covered with holes that look like they’ve been eaten but with no sign of any mites. This has created lots of blackening around the edges of the holes and the tree looks unhealthy compared to another feijoa tree planted at the same time. Could you please offer any advice.

 LEAF roller caterpillar will be responsible for the damage caused to your tree. You will notice leaves stuck together in a fine webbing and a caterpillar inside. Because they tuck themselves away, the caterpillar is hard to control.

Spray with a systemic insecticide such as Orthene. A systemic insecticide (as opposed to a contact spray) is absorbed into the plant and carried in the sap and so when the caterpillar feeds on the plant it ingests the insecticide. A contact spray such as Malathion or Maldison may also be effective. Ensure you get good leaf coverage with the spray.

Alternatively, if the tree is still relatively young and does not have any fruit set on it, trim back the affected foliage.

Are your feijoas the same variety, or are they different? It may be that one variety is more palatable to leaf roller caterpillar than the other and that will explain why one tree is affected and the other not.

• The views expressed here are not necessarily those of the RNZIH
• Content or advice may be out-of-date.