"Creative pest control"

There are lots of ways to outwit garden pests!
Sunday, 25 October 2020     

Bug on Dahlia Moonfire

My early days of gardening were accompanied by a fearsome arsenal of hideous, toxic chemicals to tackle pests. I shudder to think of them now that we have become so much more aware of the toll that strong chemicals can take on the complex web of life in our gardens and waterways (as well as potentially on our own health). Sustainable gardening is now the way forward and it is a practice that I try to follow and actively promote. It is actually quite fun to learn new ways to outwit insect foes, and I am always on the lookout for creative ideas.

In my experience, there are various categories of tactics: physical removal of pests, physical exclusion of pests, attracting predators to eat pests, and using 'insect psychology' to control pests. Physical removal is the most basic method, and one I have been familiar with since childhood, when my sisters and I were paid (at a very low rate) to hunt for and destroy snails in the family garden. We became quite adept at finding their hiding places in wood piles, under thick foliage and on the shady side of pots. I now also physically remove the adult forms of the bronze orange beetle (clad in a long-sleeve shirt and wearing goggles to protect myself against the noxious liquid they eject as a defence mechanism when disturbed!). I whack them with a stick from the branches of my citrus trees into a bucket of soapy water. On hot days, these horrible creatures may cluster low down on the trunks of the trees, where it may be easier to remove them. I use a similar technique with the annoying flea beetles that attack my Salvia plants and disfigure their leaves. With these tiny insects, I flick them into a small jar of soapy water and firmly close the lid! Orchid beetles can be tackled in the same way. Physical removal can also be used to pick off and squash caterpillars; rub aphids from stems (they can also be hosed off with a vigorous jet of water); and scrape scale from branches with an old toothbrush.

Physical exclusion covers many varied strategies. My most recent practice has been to enclose each of my developing passionfruit in an organza drawstring bag. Last year, I harvested exactly one passionfruit from what had seemed initially would be a bumper crop. I don't know exactly what ate them - possibly cockatoos, possums and/or bush rats - but it was hugely disappointing. The organza bags (available very cheaply at $2 shops) allow light in and can be tied on securely. Time will tell if the ruse works. Previous attempts at netting the crop failed, as the pests seemed to be able to get beneath the netting and then the vine became hopelessly entangled with it all. The organza bags can, of course, be used with a variety of other crops, such as tomatoes, figs and so on. They are available in a range of sizes.

Because I have many brush turkeys marauding in my neighbourhood, I always place an obelisk or some sort of protective frame over any plant that is put in. They seem magnetically attracted to anything new in the garden and they delight in digging up the plant as the scratch around in the freshly dug soil. Once the plant is established, it seems safe to remove the barrier. Some gardeners lay old, dry palm fronds on the ground in the borders as a deterrent, as it seems the turkeys don't like the feeling of walking on this material.

With my vegetables and herbs grown in pots, I often use a large wooden frame covered in gauze to place over a group of pots to deter flea beetles from my basil and mint, and white cabbage moths from any Brassica crops such as rocket, kale or watercress. This method only works for edibles that don't need insect pollination. Other exclusion ideas include making guards to place over young seedlings by cutting off the top and bottom of a plastic soft drink or milk bottle and placing this over the plant. The top can be covered with soft mesh and held in place with an elastic band for extra protection. Snails can also be deterred from attacking plants by creating a barrier of crushed eggshells or wood ash. Thin adhesive copper tape can also be stuck around the sides of a pot as snails won't cross this material.

Insect psychology is an intriguing form of pest control. The method I am currently trying is the use of faux cabbage moth decoys to keep these wretches from laying eggs on my plants. There seems to be a plague of them at the moment and they are seemingly interested in all plants in my garden, not just the Brassica family! Apparently, these insects are territorial so if they see a moth already on a plant, they won't approach. I have made some decoys from white ribbon and attached them to a wooden skewer, and it seems to be possibly working! I have also ordered some more realistic ones that bob about on a spring which I plan to dot around in my garden. Other techniques to trick insects include the use of a pheromone in an adhesive trap to lure male citrus leaf miners to a sticky demise and thus reduce the overall population of the pest; and placing a saucer of beer at ground level to exploit slugs' and snails' love of a tipple, where they drown quite happily.

Attracting predators to eat insect pests is another handy way to reduce their numbers in your garden. Birds are obviously a great help with this, so making your garden bird friendly - by providing water in a bird bath and growing plants with suitable nectar as well as a dense habit to provide shelter - will mean that birds will be your allies in pest control. Beneficial insects such as hoverflies, lacewings, wasps, ladybirds and predatory mites that eat insect pests can also be encouraged by growing plants that provide food. In general, beneficial insects are small and thus have tiny mouth parts, so nectar and pollen from clusters of tiny, shallow flowers growing horizontally on a flat 'landing platform' are best for these creatures. The Apiaceae family has blooms like this and examples include Queen Anne's lace (Ammi species) and Orlaya, as well as parsley and coriander when they are allowed to flower! The Asteraceae (Compositae) family also has flat flower clusters: what appears to be a single bloom of many of these plants is actually comprised of many tiny 'disc' flowers in the centre, surrounded by larger individual strap-shaped flowers. The disc flowers of many of the members of the daisy family attract beneficial insects. Particular favourites that thrive in our Sydney include yellow chamomile (Anthemis tinctoria), annual sunflowers (Helianthus annuus), annual pot marigolds (Calendula officinalis), Cosmos bipinnatus, Echinacea purpurea and feverfew (Tanacetum parthenium). Avoiding nasty chemical sprays that kill insects indiscriminately is an important aspect of encouraging beneficial insects in your garden.

I do use a couple of organic sprays (which only control the insects that are aimed at) when absolutely necessary: a white-oil based one for aphids, scale, bronze orange beetle when it is in its early stages during winter and early spring, citrus leaf miner and whitefly; and a neem tree extract for caterpillars and grasshoppers. However, I remain fascinated by the idea of outwitting pests and would love to hear your strategies!

 Reader Comments

1/12  Margaret - 2122 (Zone:10 - Warm Temperate) Monday, 26 October 2020

Like you, my early days of gardening involved the use of toxic materials, which, now, thankfully has changed. All your ideas are useful. I squash caterpillars, did try material bags on poppies, but birds? rats? just ate the covers and the seeds. I have not yet found the organza bags. Attracting predators works, otherwise organic sprays, especially Neem oil are useful. Aargh, how annoying that the pests ate your fabric bags! I await to see if they eat my organza ones. Hope you can find some - there seems to have been something of a 'run' on them locally after a talk at our garden club, when our speaker, Meredith Kirton, mentioned the idea! Deirdre

2/12  Kerrie - 2104 (Zone:10 - Warm Temperate) Monday, 26 October 2020

Dierdre I'd love to know where you've ordered your faux cabbage moth decoys from. I won't use any sticky papers anymore after I found 2 dragonflies impaled on them dead on 2 seperate occasions & a poor baby skint on another occasion. Unfortunately anything friend or foe that goes on them his history. Good point about the sticky papers. Specific lures inside small cardboard sticky traps are probably less of a problem. I ordered my cabbage moth decoys online from a place called The Lost Seed. Look under the organic fertilisers/pest control section. Deirdre

3/12  Valerie - 2121 (Zone:10 - Warm Temperate) Monday, 26 October 2020

That is interesting about dry palm fronds to deter brush turkeys. I will have to give it a go. Also the saucer of beer for snails. Might end up with some 'relaxed' possums or don't they like beer? Not sure if possums drink beer! The palm fronds seem to work, according to various friends who use them. Deirdre

4/12  Janice - 2067 (Zone:10 - Warm Temperate) Monday, 26 October 2020

Deidre I use an old vacuum cleaner with a long extension cord, to 'Hoover' off those horrible orange bugs which seem attracted to my cumquat trees. The bags are disposable and I throw the sealed bags into the garbage bin. However, I do use gloves and safety glasses for protection.A great idea, Janice! Deirdre

5/12  Gaynor - 5044 (Zone:10 - Mediteranean) Monday, 26 October 2020

Hi Deidre is it me or are bugs worse than ever this year? I now have at least 2 lizards living in my garden and the number of snails has decreased dramatically. I had more aphids on my honeysuckle this year than the ladybirds could eat, so decided to sacrifice the flowers, I cut them nearly all off, left some for the ladybirds, fertilized and watered the plant and the aphids are now less obvious. Although it's counterintuitive, I believe aphids etc attack plants which are not the healthiest.? Thanks, Gaynor. Lizards are great to control snails. I do believe that pests attack weaker plants. Deirdre

6/12  Lynne - 2479 (Zone:11A - Sub-tropical) Monday, 26 October 2020

Thank you for the good ideas Deidre, especially the palm frond brush turkey deterrent. Those birds just love digging up newly planted plants! Any suggestion to deter an insect that attacks the new growth on cycads? They eat all the edges of the new growth so when then leaves mature they look really ugly. I have no idea what the insect is and for the life of me I cannot actually see them on the leaves. Maybe try horticultural oil or neem oil. Deirdre

7/12  Carole - 2230 (Zone:10 - Warm Temperate) Monday, 26 October 2020

Hello Deidre, I writing to report a new class of garden pest the Australian Lyrebird. I have been living on the south side of Port Hacking at Maianbar for 24 years and have never seen a lyrebird outside the middle of the Royal National Park until this year. The body of the bird is small but the legs and feet are strong and destructive in, on or near pots and small plants, they upend pots and the contents, they scratch bulbs out etc . Watch out for the Lyrebird. I do like them though :-) Yes it has only been the last few years that I realised lyre birds can be as destructive as brush turkeys. New plants need protection as recommended in the blog. Deirdre

8/12  Pam - 3216 (Zone:10 - Mediteranean) Tuesday, 27 October 2020

I would love to hear if anyone has new ideas to deter possums. They are munching their way through the foliage of my crab apples and melia trees. unfortunately there are lots of nesting places in this area. See Marion's comment for some ideas. Deirdre

9/12  Marion - 4103 (Zone:11A - Sub-tropical) Tuesday, 27 October 2020

Great tips Deidre. For possums: I recently planted a Pierre de Ronsard rose against a fence...possum completely denuded it. It is now in full leaf again... I'vd been spraying it with diluted fish sauce after watering or rain, or every 3'4 days otherwise. I'vd also planted dogbane round the base and in a basket attached to the fence above it. Not sure which us doing the job, but so far... Great ideas, Marion. Deirdre

10/12  Leveena - 2099 (Zone:10 - Warm Temperate) Tuesday, 27 October 2020

My biggest problem is possums. My citrus can barely grow new growth without them finding it, eating it and weakening the plants. I have resorted every night to placing large plastic bags over new growth in an attempt to allow it to grow into tougher dark green leaves-they don't like older foliage! Great idea, Leveena. Deirdre

11/12  Denise - 2261 (Zone:10 - Warm Temperate) Wednesday, 28 October 2020

The Diggers Club, Victoria sells Cabbage White Butterflies on sticks in 6-packs for: Retail $11.50, Club Member $8.95

12/12  Valerie - 2121 (Zone:10 - Warm Temperate) Thursday, 29 October 2020

Thanks Marion for your post about dogbane repelling possums. For the past two years Ive massed dogbane around the base of a patio standard Regensberg rose and the flowers havent been eaten. Previously Id had to encase it in chicken wire and the possums tried to eat through that. I had no idea about dogbane doing the repelling, I just thought it looked nice as part of the border. It sounds a great method. Deirdre

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