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YOUR GARDENING QUESTIONS THIS MONTH

QLOST PASSION

I cut back my passionfruit vine and it regrew very enthusiastically. Now the leaves are wilting but don’t seem to be dying from dryness as the ground is moist. ALLAN HARKNESS, AUCKLAND

AGrowing passionfruit can very frustrating. If they’re in the right spot the vines will flourish and fruit abundantly, seemingly with minimum care. But they can also be temperamental divas and suddenly fall victim to a multitude of diseases.

You don’t mention aphids so this looks like root rot – either fusarium or phytophthora – probably due to the damp soil. Improving the drainage might help but it’s likely that the plant will collapse and die quite quickly. Have a look around the base of the stem. There might already be brown lesions or other signs of rot.

Passionfruit need perfect drainage and plants may only last three to four years before succumbing to root diseases. The infection stays in the soil so don’t plant another passionfruit vine in the same place.

If the fence is the only place you’ve got to support a passionfruit vine use a large container with a high-grade potting mix to start a new plant.

Very heavy infestations of sap-sucking passionvine hoppers can also cause plants to wilt. In spring the white fluffy juveniles (colloquially known as fluffy bums) cluster over the stems. Adults are small grey moths with semitransparent wings. As they fly away from sprays the best time to control them is winter when their lines of eggs laid along stems can be removed while pruning.

Also watch out for thrips which are more likely to appear during hot weather. Small brown spots and tiny insects can be seen on the underside of the leaves which turn silvery grey and look crisp and dry.

QPRICKLY PROBLEM

Why does Ruud Kleinpaste want to eliminate hedgehogs? (Jan 2019). In England they are protected. I love them in my garden because they eat snails. JEANNETTE SORENSEN, HASTINGS

AHedgehogs out-compete native species by eating the invertebrate food supply needed by birds and lizards. They prey on birds – eating nestlings and eggs. They decimate native species including tuatara, weta, kauri snails and skinks.

Ruud Kleinpaste studied hedgehogs and their diet. “Yes, they are cute and clever and I am in awe of their defence system,” he says.

“But, if we are to restore New Zealand’s biodiversity, we will need to seriously look at limiting or getting rid of predators that do not belong here and that, unfortunately, is the case with the hedgehog.”

“And the biggest problem is that they eat carabid beetles which are nature’s experts in eating the eggs of slugs and snail. They are eating the very thing that we want in our gardens to control slugs and snails.” Barbara Smith

QPRETTY IN PINK

These flowering trees line several streets in my central city suburb but no one seems to know what they are. They are evergreen with dull grey-green leaves. MICHELLE SPENSER, AUCKLAND

ALagunaria hail from Lord Howe and Norfolk Islands and Queensland. In the Malvaceae family they’re related to hibiscus.

Lagunaria prefer full sun and good drainage. They can be pruned as hedges or grown as tall columnar specimen trees if new growth is removed from the trunk.

But there’s a warning in the common names – itchy bomb tree or cow itch tree. The pink or mauve flowers are followed by oval seed capsules with tiny, bristly hairs that cause severe skin irritation.

Lagunaria are grown as street trees in many parts of New Zealand but has been classified as “under surveillance” by Auckland Council as they are fast growing and can out compete coastal species due to their tolerance for wind, salt, drought and poor soils.