How I Grow
Gardening chats.
How I Grow
Defending Your Brassicas: Winning the War Against Cabbage Moths
Are cabbage moths and butterflies turning your garden into a battleground? Join me as we arm you with the tactics to defend your brassicas against these voracious vegetarians. We'll identify the enemy – those fluttering white foes and their ravenous larvae – and I'll share my arsenal of tried-and-true strategies. Discover how fine netting, aromatic companion plants, and even moth scarecrows can protect your cabbage, broccoli, and kale. And should an infestation strike, learn the crucial steps for manual caterpillar combat to keep your leafy greens safe. This episode is a treasure trove for any gardener waging war on cabbage pests.
As our gardening saga draws to a close, I encourage you to join forces with fellow green thumbs in our Seed Collection Community on Facebook. It's a place brimming with shared wisdom, where your love for the soil can find kindred spirits. And don't forget to visit www.theseedcollection.com.au – your go-to resource for seeds and sage advice. Whether you're a seasoned horticulturist or just starting to sow your first seeds, this community and our website are wellsprings of gardening knowledge, ready to help your garden grow with health and vigor. Thanks for tuning in and may your garden be bountiful!
'How I Grow' is produced by The Seed Collection Pty Ltd.
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You're listening to how I Grow with the Seed Collection, and today we'll be talking about how to best manage cabbage moths, butterflies and caterpillars in your garden. In this episode, we'll delve into how to identify, deal with and deter these produce thieves. This is especially helpful for those of you who love your brassicas and leafy greens. Cast an eye over almost any vegetable patch and you're sure to see a brassica or two. This family of veggies is hugely popular with home growers thanks to its wide variety and relatively easy cultivation. Brassicas include plants like cabbage broccoli, rocket cauliflower, kale, bok choy and Brussels sprouts, just to name a few. Unfortunately, it's not only gardeners who appreciate the many possibilities that brassicas offer. Cabbage moths and cabbage butterflies make a beeline for them and if left to their own devices, they'll they waste to your precious crop in next to no time. So what are cabbage moths and butterflies? Here in Australia, there are two main species of brassica-loving insect pests. Namely, these are cabbage moths Plutella Zioastella and cabbage white butterflies, pierras Rapae. These two insects aren't actually closely related and they look very different, but they do share similar habits, cause similar problems and are dealt with in similar ways too. Adult cabbage moths are roughly 10 millimeters long and mottled gray with a diamond pattern on their wings. The more familiar cabbage butterfly is a little larger, at around 40 millimeters, and has white wings with small black spots on the corners. Despite the visual and biological differences, the terms cabbage moth and cabbage butterfly are both widely used to refer to either species and, as the name suggests, these pests love to feast on a growing cabbage, but, as if our cabbages aren't enough for them, they'll actually feast on the entire brassica family. The adults are harmless in themselves, but if given a chance to lay eggs, an army of hungry caterpillars will soon follow. Cabbage moths produce light greenish brown caterpillars with a darker head, while butterfly larvae are a smooth greenish blue. However, it's not necessary to positively identify a species, because, when it comes to food crops, no caterpillars are particularly welcome. If they're allowed to feed uninterrupted, the larvae will chew a network of holes, often leading to leaf loss and the eventual skeletonization and death of the plant.
Speaker 1:There are some deterrents techniques, though. There are three main ways of deterring moths from laying eggs on your brassicas, and these are netting, companion planting and decoys. If you're opting for netting to form a physical barrier, be sure that it's very fine, so that it works in stopping the moths from reaching your plants. Ensure the net's fully enclosed each plant, but don't allow the net to physically touch it. If the netting is resting on the brassica, a moth can too, and you can buy dedicated butterfly protection nets. But if you'd rather reuse or recycle which is a great option an old mozzie net will do the trick, or even a flywire from window or door screens if you have some laying around. It is important to note, though, that netting has a drawback of preventing more useful access, like that of the moths' natural predators. If eggs have already been laid, the caterpillars will have free rain to feed, safe from birds and other predators. So it's best to net prior to an infestation.
Speaker 1:Another option, and this is my favourite, is companion planting. As is often the case, companion planting can provide a range of solutions to a caterpillar problem. Isn't it fantastic that a solution to a plant problem can actually be more plants. First up is planting some white clover, which is like a living mulch. The white flowers blowing in the breeze also give the moths the idea that this spot is already taken, and they're sent masks that of the brassicas. Strong smelling herbs like lavender, sage and rosemary seem to deter cabbage moths from settling in laying eggs. Try planting them around the edges of your patch to form an odor barrier that doesn't restrict your own access. The extra bonus is that not only will your brassicas be afforded some more protection, but you'll get to enjoy the benefits of these lovely herbs too. And if this doesn't work, you could grow landcress as a dead end decoy. Adult moths are strongly drawn to this plant, but the leaves contain toxins which are lethal to caterpillars. Any eggs laid on landcress will be the last in their family line.
Speaker 1:If you've exhausted these options, you could try growing some decoy plants that the moths love, like nasturtiums, dill and mustard. These will draw the egg layers away from your main crops as well as look lovely in your garden, but it does risk encouraging them to hang around. And finally, we have decoy moth scarecrow. Surprisingly, cabbage moths are incredibly territorial and they'll avoid laying eggs where there's already competition for caterpillar food. Take advantage of this by using moth scarecrow to encourage real moths to find less crowded areas.
Speaker 1:You can buy plastic moth-shaped decoys to place around your brassica patch, but it's a simple and fun job to make your own if you like to get creative now and then. To do this, simply cut white plastic sheeting or old shopping bags into roughly moth-shaped pieces of around 40mm across. Fix these to the end of twigs, skewers or canes and plant them next to the target plants. To butterfly eyes, the plastic fluttering in the breeze is a convincing impression of a rival. So what if you already have an infestation? Unfortunately, cabbage moths are determined and plentiful, and even the best deterrents tactics can sometimes fail.
Speaker 1:If you're facing an infestation, fast action is important to save your plants. Manual methods are the simplest and quickest way to make an impact. Pick your brassicas for caterpillars, particularly on the undersides of the leaves, but also deeper within the plant hearts. Pick off any larvae you find and dispose of them in whichever permanent way you prefer. This requires a little bit of time in the now, but will save you lots of it in the future. Repeat this hunt every day and you can quickly get on top of the larvae population before your crop is depleted. To be thorough, also remove any clutches of eggs to prevent new larvae from hatching. If you'd rather not touch them, use a light hose or powerful garden sprayer to knock them to the ground. Once on the soil, they'll be easy targets for birds, beetles and other predators. This method isn't the most reliable, though, so if you can opt for picking them off first, these manual methods are effective when your patch isn't too big or the infestation isn't too severe.
Speaker 1:More serious problems require something a little more drastic, like anti-caterpillar sprays. There are plenty of commercial insecticide sprays for controlling caterpillars, some organic and eco-friendly, others less so Many are based on a natural pesticide called pyrethrum, which works against caterpillars, aphids and many other pests. Unfortunately, these can also cause problems for beneficial insects like ladybirds. Because of this, sprays based on a bacterium called bacillus thuringiensis are often preferred instead. These products are most commonly sold under the dipole brand. These sprays have several strong advantages. They're highly selective, only affecting leaf-eating caterpillars among insects. They're harmless for birds and other wildlife. The sprays are safe for use on food crops with no withholding period.
Speaker 1:The bacteria are derived from natural sources and the spray is classed as organic. Dipole spray works as a toxin, killing the caterpillars two or three days after they consume treated leaves. It is only effective against larvae in their active feeding stage, so several treatments may be needed to clear an infestation. To use this, mix the powder with water according to the instructions and spray across the whole plant you wish to be protected. Reapply after rain and also every few days as the bacteria break down in sunlight. Even though dipole is organic, safe and effective, you may prefer a more homemade spray that's completely free of chemicals. To make a quick and easy spray, simply mix equal quantities of white flour and boiling water into a smooth paste, dilute with enough cold water to make the liquid sprayable and then spray the affected plant. As the mixture dries, the flour glues the caterpillar in place and suffocates them. While this homemade spray is chemically safe, it can also spell trouble for beneficial insects, so please use this with great care.
Speaker 1:Attacking a caterpillar problem on all fronts is the best approach for long-term success, so try as many of these tactics as possible. Be sure to include things like attracting predator wasps and other insects to your garden by growing plenty of blooming herbs and flowers. Continue digging over your veggie beds throughout winter, exposing dormant pupae to hungry birds. Plant a living mulch, such as white clover, around the plants. The white flowers act on the same territorial principle as plastic decoys, while the fragrance masks the attractive brusic ascent. Adult butterflies and moths are generally benign and beneficial in a garden. Unfortunately, the same can't be said for their hungry youngsters. If you value your brusicas. It pays to treat cabbagemouth caterpillars with a firm hand and keep their numbers in check.
Speaker 1:Now I'd like to go over some of the questions we hear asked on this topic. Are cabbagemoths more of a problem in certain areas? Yes, the prevalence and severity of cabbagemouth problems can vary in different regions. Several factors contribute to the distribution and impact of cabbagemoths in specific areas. For example, cabbagemouths thrive in moderate to warm climates. Regions with consistent temperatures and suitable humidity levels provide a more favorable condition for their development, and areas where brusica vegetables are extensively cultivated are much more likely to experience cabbagemouth issues. Large-scale monoculture, which is the planting of a large crop of the one variety, can create an ideal habitat for these pests. Overwintering is another factor. Cabbagemoths often overwinter as pupae in the soil. This means that warmer regions may have more continuous breeding cycles, leading to a higher population of moths. We also need to consider things like natural predators. The presence of natural predators, such as parasitic wasps, spiders and birds can all affect cabbagemouth populations. Regions with a diverse ecosystem supporting these predators may experience lower cabbagemouth problems. And then this human activity. This includes the physical transportation via people of infested plants or soil. This can certainly contribute to the spread of cabbagemoths to new areas. It's important for farmers and gardeners to be aware of local conditions and adopt appropriate pest management strategies to mitigate these problems. Thank you for watching. Monitoring, early detection and the use of integrated pest management techniques are crucial for effective control in any given region.
Speaker 1:What is the complete life cycle of cabbage moths? The entire life cycle of a cabbage moth, from egg to death, can vary depending on environmental conditions like temperature and food availability. On average, though, the complete life cycle takes around four to six weeks. This cycle consists of four stages Egg, larvae, which is the caterpillar, pupa and adult. Here's a brief overview of each stage the egg Adult female cabbage moths lay small, spherical eggs on leaves of host plants, which are usually members of the Brassica family.
Speaker 1:Lavae the caterpillar. The eggs hatch into larvae. These caterpillars feed on the leaves, stems and sometimes the developing heads of your vegetables, causing damage to the plants. Pupa After a period of feeding and growth, the caterpillar enters the pupil stage. Pupation often occurs in the soil or in nearby vegetation. The pupa is a non-feeding transformative stage, and adult the adult cabbage moth emerges from the pupa.
Speaker 1:The moths are nocturnal and typically have a brownish or grayish appearance with mottled patterns on their wings. Adult moths are responsible for mating and laying eggs, completing the life cycle. This life cycle can vary somewhat depending on environmental conditions and the specific species of cabbage moth. How long does it take for cabbage moth eggs to hatch into larvae? The time it takes for this to occur can vary based on temperature and environmental conditions. Generally speaking, though, it takes around three to seven days. Warmer temperatures often accelerate the hatching process, while cooler temperatures may prolong it. After hatching, the larvae begin feeding on the host plant, continuing their growth and development through subsequent instas before entering the pupil stage. How many eggs does one cabbage moth lay? Cabbage moths are prolific breeders, with females capable of laying hundreds of eggs during their short adult lifespan. This reproductive capability contributes to their potential as agricultural pests.
Speaker 1:What do cabbage moth eggs look like? Cabbage moth eggs are tiny and typically spherical or oval in shape. They are most commonly laid in clusters on the underneath of leaves, but can be laid as a singular egg too. The colour of these eggs can vary, but they are often light, yellow or cream coloured. They are small, measuring around 0.5 to 1mm in diameter, so they are very hard to spot. The female cabbage moth will often choose the underside of leaves to attach her eggs. This provides some protection for the developing eggs. Due to their small size and colouration, these eggs can be challenging to spot, especially when scattered amongst the foliage. If you suspect the presence of cabbage moth eggs in your plants, carefully inspect the underneath of leaves for small round structures attached to the surface. Early detection of eggs can be crucial for effective pest management and prevent extensive damage from the hatching larvae.
Speaker 1:If you have any questions or would like to discuss this topic, or any other garden related topic for that matter, please connect with us and many other garden enthusiasts in our group on Facebook, the Seed Collection Community. You've been listening to how I Grow, produced by the Seed Collection in Melbourne, australia. It is our aim to make gardening more accessible to more people, and this podcast is one of the many ways in which we're doing that. If you don't already know who we are, jump online and visit wwwtheseedcollectioncomau. You'll find a treasure trove of gardening information, as well as a huge range of seeds and garden supplies and accessories. That address, again, is wwwtheseedcollectioncomau. Thanks for listening.