Plant Doctor Archive

Poorly pepper tree

I HAVE a desperate request. We have a beautiful 10-year-old Peruvian Pepper tree and for the second time in three years, it is losing its leaves. The first time it did so was in summer and then its twigs died and snapped off. We thought it was dead, then it burst with new growth and covered itself with a copious layer of leaf. Now it's doing it again, in spite of plenty of rain. The only comment I can make is that the lawn underneath it is thick with moss. Please help us.

IT sounds like your pepper tree is suffering from a pest first found in Auckland a few years ago, but which is now quite widespread. It's a sap-sucking psyllid from South America called Calypha schini, which seems to attack only pepper trees, particularly the Peruvian species, Schinus molle.

Moss in the lawn beneath your tree suggests the possibility of poor drainage, but the main reason for leaf loss at odd times of the year will be the psyllid. The adult is a tiny winged insect about the size of an aphid which can travel quite long distances, particularly in a breeze, but it's the larvae that cause all the damage. They establish themselves in pits on the underside of a leaf, causing blister-like lumps to appear on the upper surface. They feed on the sap and, if an infestation is severe enough, the plant can be so debilitated that leaves drop and shoots die back, as you've discovered.

Healthy trees may recover, but are often attacked again. In some parts of the country even mature pepper trees have been so badly affected they have had to be cut down. Spraying with a systemic insecticide, such as Rogor 100 or Orthene, as soon as blisters appear on the leaves, could help control the pest, but I wouldn't recommend it as the hazards of spraying a large tree are too great. I'm sorry to say the days of Peruvian pepper tree being a good tree for certain parts of the country are numbered.

Interestingly, the Brazilian pepper tree (Schinus terebinthifolius) seems to be relatively unaffected, but it doesn't have the graceful foliage and attractive gnarled trunk and branches of its Peruvian cousin.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.