My Laotian neighbour popped his head over the fence this week and asked why the leaves on his recently planted nectarine tree were curled and blistering. The conversation wasn’t as straightforward as that, though. English is his second language and I have no Laotian.

He is a recent migrant and a prolific gardener. I only wish we could have better communication, so I can learn more about the unusual fruit trees and vegetables he grows. And I have a suspicion that he is suspicious of my intent, but we’re working on it.

I was so pleased that he felt I could help him with his nectarine problem, a fruit he has never grown before. And I wish I could give him some books to read up on common garden problems in New Zealand, but he just keeps shaking his head and hands. However, we did make some headway with his problem by pointing, gesticulating and making spraying noises.

His problem is leaf curl (Taphrina deformans), a common one at this time of year that could have been curtailed in autumn, but can still be tamed in spring.

According to Waimea Nurseries Kate Marshall this disease affects peaches, nectarines and apricots (plum trees can get curling leaves, but this is caused by aphids rather than the leaf curl fungus). Kate has written extensively on the problem for NZ Gardener ‘s special edition ‘grow your own fresh, healthy fruit homegrown fruit trees’.

Symptoms include curled, blistered new spring foliage – affected leaves can have raised, swollen, whitish-green, pink or red blisters. These leaves will drop from the tree, so a bad case can result in severe defoliation. New, healthy foliage will appear, but your tree will still harbour fungal spores to reinfect itself the following spring.

Kate says the best prevention is a well-timed application of copper oxychloride (which I went and bought for my neighbour as he is always sharing his fruit and vege with me) and good cultural hygiene.

As this disease over-winters in bark crevices and around the new buds, spray with fungicide at leaf fall in autumn to kill the spores. Remove all mummies (dried-up, decaying fruit) from the tree, and rake up all the fallen leaves.

Follow up with two more applications of copper oxychloride in spring – once when the flower buds begin to swell and again two weeks later.

A fungicide spray can be used instead of copper oxychloride if the infection is bad or if your climate is very warm and wet.

Kate says old-time gardeners hammer copper nails into the trunk, but there is no solid evidence that this works.

Resistant varieties to plant include ‘April White’, ‘Dixired’ and ‘Golden Glory’ peaches.

Due to their natural tight branching habit, dwarf stonefruit (such as ‘Honey Babe’ and ‘Garden Delight’) can be susceptible to leaf curl. It’s important to remove all decaying leaves and fruit from these trees in autumn, and to give them a good dose of copper-based fungicide to target any spores hiding in the nooks and crannies of their little branches.