By Arzeena Hamir, MSc
I was almost ready to believe that we would be able to have a slug-free garden this spring but the rains came and the slugs returned with a vengeance. Still, slug control can provide the perfect opportunity to describe how organic gardeners should approach a pest so I’m turning this into a learning opportunity.
First and foremost, organic gardeners need to understand that they will never “eradicate” or “eliminate” all the pests that try to damage their plants. Setting the bar lower to tolerate some damage will go a long way into keeping both your harvest and your mental health a good level. A few holes in leaves or less than 100% germination is totally acceptable.
Second, understanding your pest is necessary to figure out how to manage them. For slugs, that means knowing that they are a nocturnal creature whose soft, gooey body requires lots of moisture and tall vegetation to hide out in during the day. Other insects only do their damage at the larval stage, not the adult. This knowledge can help gardeners understand how and when management can be done and the following steps can be used for any pest.
One of the most effective and least damaging methods is to try to prevent slugs from proliferating. In the fall/winter, you may run across a cluster of milky colour eggs. These eggs can be moved into a forested area, fed to your neighbour’s ducks or thrown in your compost where they’ll help digest all the woody material there.
Another prevention technique is to move mulch away from tender plants like asparagus, hostas & beans. Mulch is a great medium for slugs to hide out under and by exposing soil, it forces them to be in the sun and exposed to predators, which they hate. A layer of copper, sharp sand or crushed eggshells encircling your plants can even repel slugs.
For other pests, prevention can look like crop rotations, not overfertilizing so that plants grow thick cell walls, or using floating row covers or cardboard collars to physically block pests from laying their eggs on your plants.
Garter snakes and black ground beetles do eat baby slugs so keeping rock piles for the former and tall grasses for the latter will help nature keep the slugs in check.
There are actually far more types predatory insects than there are pests but predators need a population to eat before they’ll arrive so sometimes it just requires gardeners to be patient. Letting cilantro, parsley, dill or fennel go to flower will attract a wide variety of beneficial insects
As gross as it sounds, this is by far the most effective method of bringing down slug numbers. Go out at dusk with some tongs or disposable chopsticks and a bucket of soapy water. Young children will do this for free! I find the going rate for older kids is 10 cents a slug. I’m sure I can sponsor a few college funds at my place.
Hand picking can also be done with cabbage moth larvae, cut worm, and other larger bugs. Even weevils can be picked off peas if you put down a white cloth in the evening and shake them off your plants.
You may have heard that slugs are attracted to beer, at least the yeasty smell that beer gives off. Leaving tuna fish cans or small yogurt containers of beer around the garden can trap a surprising number of slugs a night.
Some pests are attracted to the colour yellow so you can often find yellow sticky traps in garden centers to help you trap bugs like flea beetle. However, many other beneficials like that colour as well so it’s recommended that you drape your plants in a floating row cover or sheet first so that you don’t accidentally trap them as well.
When making a spray from ingredients found at home, remember that not all household ingredients are safe or benign. I don’t recommend using salt, mothballs, or ammonia in the garden. The impact on your soil is just too negative to justify any kind of control.
However, garlic and even milk have been shown to be effective for pest control. Crushed garlic can repel aphids and a 50% dilution of milk has been shown to prevent powdery mildew. Add a few drops of dish soap before applying and apply after dusk to prevent hitting bees and other pollinating insect.
Store-bought organic controls
There are few products that I actually purchase for pest control but iron phosphate (also known as ferric phosphate) pellets are one that I buy for slug control. It’s a very effective but safe product (unlike the old metaldehyde slug baits) that birds and other animals can consume without issue.
Diatomaceous Earth is a great stand-by pest control that works on both hard-bodied and soft-bodied insects that are found at soil level and will walk through it. It will soften in rain so does need to be reapplied. It’s the only thing I’ve found that will manage woodbugs.
I also purchase Safer’s soap spray for indoor plants that tend to get aphids. The spray can be used outside as well but as with homemade sprays, wait until late in the day to prevent hitting bees.
Hopefully, this guide will help you understand the different ways you can approach pest management in your garden. Identifying and getting to know your pests since understanding their lifecycle is key to figuring out where and when to apply the safest pest control possible.
Arzeena Hamir is an organic farmer, agronomist, politician, and mother from Merville, BC. Arzeena and her husband own Amara Farm, a 26-acre certified organic vegetable and blueberry farm just north of Courtenay, BC.
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