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Homegrown Fruit: Pests and disease-reducing strategies

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By Kath Irvine and Jason Ross

Homegrown Fruit: A practical guide is an accessible and comprehensive guide to growing fruit trees, bushes, vines and brambles in Aotearoa New Zealand.

The authors have a wealth of experience between them, and guide readers through everything from planning a home orchard, to specific types of fruit and their requirements, to care and pruning, pest, disease and weed control, and much more.

The following is a section on strategies to reduce pests and disease, extracted with permission from Homegrown Fruit: A practical guide, by Kath Irvine and Jason Ross (K+J Books, 2025) $58 RRP

ABOVE: Cover image of Homegrown Fruit, and Jason Ross and Kath Irvine (Mickey Ross Photography)

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We’re big fans of sidestepping pests and disease – that’s why we’re so keen on well-suited varieties, and on staying in touch with our trees and keeping health humming along. Even so, pests and disease do happen! Little bits here and there are no worries, but more than that and it’s a good idea to ponder why. It’ll be a stress of some sorts – weak vigour, overfeeding, extreme weather, or because the tree isn’t planted in its happy place.

If a tree continues to get hammered every year in spite of all your love, feel free to chop it down, mulch it up, and try another variety. That in itself is an excellent pest- or disease-reducing strategy – to only grow trees that thrive easily. The younger your orchard is, the more important it is to act on the first signs of pest or disease. The more established, diverse, and healthy your orchard, the more important it is to watch and let things take their natural course. If at any point tree health starts to be compromised, step in with our solutions below.

ABOVE: Illustration by Jason Ross

Pest-reducing strategies

Before you rush in to squash or spray, find out about the bugs you see on your fruit trees and make sure they are foe. You will find most are orchard friends. It’s really useful to understand what the different phases of bug life cycles look like – both for pests and predators. The juveniles can look radically different to the adults.

5 spray-free strategies

Our goal is to manage all pest problems without sprays, to lean into the wondrous network of unseen support that’s constantly in motion in our orchards.

Predatory insects

Keep a wide variety of pests in check with a wide variety of predatory and parasitic insects: parasitic wasps, hoverflies, ladybirds, praying mantis, spiders, dragonflies, damselflies, assassin bugs, lacewings, various beetles, frogs, and even earwigs – the more the merrier! Entice them in with a spray-free, wild haven, a year-round supply of nectar and pollen, and of course, some pests to eat!

Wild birds

Birds are a quid pro quo – while you may want to protect your ripening crop from them, the rest of the time birds like wax-eyes, starlings, chaffinches, and fantails are voracious gobblers of insects.

Digital control

Squashing grubs, caterpillars, or aphids is a quick and easy solution on a young tree, a dwarf or espaliered tree, or a reachable vine. Curled or folded leaves are a sign that a grub or caterpillar lurks within – open them up to see. Dimpled leaves indicate a sucking insect is at play – flip them over to check. Webbing is another sign – poke about and be nosy! You don’t need to squash every single pest: get the bulk of them, or the ones within reach – leave a few for the predators. Keep at it during your check-ins.

Fruit and spur thinning

Thinning reduces pest numbers by removing their habitat – the cosy home that’s created where fruits touch.

Chickens and ducks

Chickens scratch up and gobble overwintering grubs and larvae. Ducks love slugs and snails, and both forage on a broad range of pests, from aphids to grasshoppers.

Two safer sprays: Neem and Bt

While it’s our goal to be spray-free, there are times when we are both very grateful to have Neem and Bt in our toolkit. Both must be ingested to work, so the only insects that come to grief are the ones sucking or chewing the foliage or fruits. Bees and predatory or pollinating insects aren’t eating foliage or fruits, so they stay out of harm’s way. Many natural insecticides, like pyrethrum, garlic, or rhubarb spray, are contact killers – they nail everything they touch. We don’t recommend them.

The key to success with Neem and Bt is to completely cover the foliage when you spray, and to follow up with a couple of repeat sprays to catch the next gen of egg hatchings. Repeat sprays are essential! Use your observations to guide you as to how many repeats you need.

SPRAYING TIPS
Spray at dawn or dusk, in dry weather. Use a fresh mixture each time – make a small batch so that you use it all. Rinse out your sprayer afterwards, especially the nozzle, and leave it open and upside-down to air out and dry.

Neem

Use for all sucking insects: aphids, woolly aphids, scale, thrips, passionvine hoppers, green vegetable bug, and cherry/pear slug (sawfly larvae).

  • Passionvine hopper adults are impervious to spray – catch them at the juvenile ‘fluffy bum’ stage. Repeat at three-day intervals. By the third spray, the population will be greatly reduced. Continue in this way until there are none left.
  • Woolly aphids are a more intense pest because they suck on both roots and tops. If there are tell-tale cottony growths around the root crown, apply Neem granules to the soil at the base of the tree in tandem with using Neem sprays

Bt

Bt is short for Bacillus thuringiensis. It’s the active ingredient in many caterpillar-specific sprays. Use it for raspberry bud moth, leaf roller caterpillar, codling moth, and guava moth.

Codling moth and guava moth get a special mention because natural predators are in short supply in NZ, and they aren’t so much a reflection of stress as they are a reflection of a neighbourhood that’s heaving with them. Success comes from doing a range of things that target different stages of their life cycles.

  • Spray with Neem + Bt together, weekly from petal fall.
  • Check over young fruits for tiny entry holes where larvae have burrowed in. There may also be frass – tiny piles of sawdust-like excrement – at these sites. Remove fruits and feed them to your chooks or drown them in a barrel of water.
  • Immature fruits that fall often contain larvae – send your pigs in or pick them up; this stops the next generation of moths emerging.
  • In winter, let chooks in to hunt overwintering larvae – wax-eyes and ground beetles also help with this. Needless to say, clean up all windfalls in case they contain larvae.
  • Prevent guava moth by covering trees with insect mesh soon after pollination, when fruitlets start to develop.

Homegrown Fruit: A practical guide, by Kath Irvine and Jason Ross (K+J Books, 2025) $58 RRP

Azadirachta indica - the neem tree

Neem: Nature’s healing gift to humanity

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Book review by Katherine Smith

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It’s appropriate that the cover of this book features its author, Klaus Ferlow, standing beside a neem tree, his left arm reaching around to embrace its trunk in a fraternal greeting. That’s because Ferlow (originally from Germany) helped to introduce people in North America to the healing properties of the neem tree, after emigrating to Canada in 1975 and founding Ferlow Botanicals approximately 20 years later.

Klaus Ferlow credits his (now late) wife Rose with introducing him to neem by urging him to watch a TV programme called ‘What’s in a Neem’, narrated by David Suzuki. Inspired by the documentary, Ferlow obtained some neem extract and applied a neem cream to the psoriasis on his scalp and elbow and got relief from this condition in just three weeks. Having previously trained as a herbalist, he decided to set up a business to bring the benefits of neem to the North American market. Ferlow Botanicals is now rum by the Ferlows’ sons, Peter and Harald, and Ruth (Peter’s wife).

Klaus Ferlow has maintained his interest in neem and founded the organisation Neem Research “to promote neem for human, animal and environmental health”. His new book, Neem: Nature’s healing gift to humanity, includes profiles of neem researchers and entrepreneurs. He gives special credit to the late Professor Dr. Heinrich Schmutterer as ‘the father of modern neem’. It was his observation that neem trees had survived a plague of locusts that swept through Sudan when he was on a field trip there in 1959 that caused him to wonder if a natural insect repellent could be present that led to his work researching neem and writing the definitive textbook on neem, The Neem Tree (1995, 893 pages).

From the home of the neem tree in India, knowledge about the tree has spread to North and South America, the Caribbean, Africa and Australia.

Among the examples described in the book is Abaco Neem, a farm in the Bahamas that includes neem trees intercropped with fruit trees. (In all, 120 varieties of fruiting and flowering trees are grown on the farm.) Spiders and beneficial insects like butterflies and bees have thrived in this environment and hives on the farm allow neem honey to be produced as well as other neem-based health and personal care products. Some of these products incorporate beeswax from the hives. Among the products produced by Abaco Neem is a neem-based insect repellent.

ABOVE: Collection of neem seeds for the preparation of seed balls. Photo: Paryavarana Margadarsi Vaisakhi via Wikimedia Commons

The farm has organic certification and the fruit from the neem trees also has the benefit of providing food for birds; a visiting intern from France identified almost 40 different bird species on a single day.

In addition to being used to promote human health when used as a supplement or medicine, neem has the potential to boost food production. Neem extracts can be used as insecticides and ‘neem cake’ made from defatted neem seeds can be used as a fertiliser that also helps to protect plants from nematodes. The book also reports that a constituent of neem (azadirachtin) is being developed as a food additive for farmed salmon in Scotland to treat sea lice infestation of the fish.

In India, a company called Nisarga Biotech has been producing supercritical extracts of neem (using CO2 to extract constituents from the plant) which may be used as botanical pesticides, or in cosmetics or personal or medicinal products. Their product line includes a neem toothpaste and mouthwash – a modern iteration of the tradition in Indian villages of using neem twigs as a toothbrush. The company has also ‘secured a patent for the manufacture of neem leaf CO2 extract for use in treating oral and colon cancer’.

Neem: Nature’s Healing Gift to Humanity is a testament to the hard work and vision of its author and all the individuals whose businesses feature in its pages.

• Published by Neem Research, 2016, 258 pages, ISBN 9780993727504

• Available via local booksellers or from Neem Research.

About the reviewer: Katherine Smith is the co-editor of The NZ Journal of Natural Medicine, which first published this review in issue 54 (February 2025).

Photo at top: Azadirachta indica – the neem tree. Photograph by Kwameghana (Bright Kwame Ayisi) via Wikimedia Commons