Our Plant Doctor Andrew Maloy dispenses expert advice on solving garden problems in every issue of Kiwi Gardener.
About four years ago I planted six different feijoa standard plants, ‘Apollo’, ‘Golden Goose’ and ‘Kakapo’. They’ve grown well but had few flowers and most don’t set fruit. This year we only got two feijoa! There seems to be plenty of pollinators around because the passion fruit nearby and other flowers all were pollinated. I applied nitrate of potash fertiliser last winter and it didn’t seem to make any difference. Also, something is eating the leaves. Can you offer some tips?
J Boock, Wellington
Feijoas can take a few years before flowering well. Your trees should flower better now they’ve reached above the fence where they’re exposed to more sunlight. It looks like they’ve been pruned to make them bushy, which is all well and good but that can affect flowering. I wouldn’t prune them at all for at least a year to see how well they flower next summer. Feijoa flowers are almost exclusively pollinated by large birds like mynas, blackbirds, thrushes and tūī as they feed on the sweet petals. A large range of insects also visit them, but research shows they are not particularly good pollinators of feijoa flowers.
Some feijoa cultivars are said to be self-fertile; that is, they can set fruit by pollination with their own pollen. Others are said to be self-infertile and need pollen from another cultivar to set fruit. There seems to be some confusion in the literature depending on where you look – for example, one source states ‘Kakapo’ is self-infertile while another says it is self-fertile. Regardless, the cultivars you have should be capable of producing fruit once they start flowering as long as their flowering times overlap and there are birds around in summer to do the pollinating job. Adding a bird bath to the garden might help.
The damage to the leaves is caused by leafroller caterpillars, which roll up a fresh young leaf and fix it in place with webbing to make a protective shelter in which they can eat away at the leaf. By the time you see the damage, the caterpillar will often have pupated and flown away as an adult moth to mate and start the cycle over again. Check fresh new growth for rolled up leaves or leaves stuck together. If you pull them apart you might find a wriggling caterpillar, which you can squash or throw on the ground for the birds to deal with. Once you know what to look for you can just squash the little blighters inside their shelters to save time. If that doesn’t appeal, there are insecticides you could use with low toxicity that are safe to use on edible plants. Yates Success Ultra Insect Control contains spinetoram, which is derived from beneficial soil bacteria. Sprayed onto the plant, it moves into the leaves to be ingested by the caterpillars when they feed. Or you could try Kiwicare Organic Insect Control with Pyrethrum. Make sure to read and follow the product label recommendations.