If you’re reading this, you’ve likely encountered onion thrips. These pests feed on the leaves of many alliums, including onions, shallots, leeks, and chives.
The damage they cause can be significant. While there are chemical treatments available, many gardeners would prefer to take a natural approach to get rid of these pesky pests.
In this article, we’ll discuss some natural methods for controlling onion thrips in your garden.
Damage Symptoms
One of the first signs that you have onion thrips (thrips tabaci) is witnessing the damage they cause. They feed on many plants, but onions themselves are a favorite.
Onion leaves affected by onion thrips will discolor with white patches, curl, and twist [1]. Additionally, if you look closely you’ll see silvery streaking.
The onion bulbs themselves can also take on damage from onion thrips. You might have undersized bulbs.
Crops Affected By Onion Thrips
These tiny insects are attracted to a variety of plants, including chives, alfalfa, green onions (scallions), shallots, garlic, and leeks [2]. And as mentioned, they can cause serious damage to the crop.
Therefore, it’s important to check your garden regularly for signs of a possible infestation, especially in hot, dry weather, so that you can take action immediately.
Be sure to inspect all plants in the onion family and those listed above for any signs of silver lines and white patches on leaves.
How to Get Rid of Onion Thrips Naturally
Let’s dive into some of the best natural methods to keep your crops safe from thrips.
1. Sprinkler Irrigation
Overhead watering or sprinkler irrigation is a great way to keep these onion pests at bay. It will wash them off, reducing the build-up of thrips populations.
Farmers that utilize overhead irrigation on their fields have lower thrips problems.
2. Natural Predators
There are a few natural enemies that can help to control onion thrips. Examples include big-eyed bugs, lacewing larvae, parasitic wasps, minute pirate bugs, ladybugs, and predatory mites.
Now, if you’re going this route, you’ll need to find a way to attract and keep these natural predators around for them to be effective.
With a little research and commitment, this biological control of onion thrips is a great way to protect your plants.
3. Straw Mulch
Straw mulch has proven to help reduce thrips populations in onion beds [3]. Moreover, it’s easy to install and helps retain moisture in the soil, meaning that your onion crop stays healthy and happy.
It’s also great for the environment. By using straw mulch, you’re preventing soil erosion and helping maintain a healthy environment for beneficial microorganisms that break down organic matter in the soil.
4. Companion Planting
Planting marigolds near onions is said to help repel onion thrips.
Companion planting onions with fennel, potato, carrots, tomato, cucurbits, or chrysanthemum can also help in repelling thrips or acting as trap crops to draw away these pests.
Plant these in between rows of onions or along the borders of your garden for extra protection.
5. Practice Good Field Sanitation
You can fight onion thrips with the simplest and least costly method of all: good field sanitation.
Regularly monitoring and removing volunteer onion plants, crop debris, and unneeded plant material can help to significantly reduce onion thrips populations.
6. Soapy Water
One effective home remedy that worked for us is soapy water. Since it works so well in getting rid of bugs and other insect pests, we decided to give it a try.
All we did was mix 2 tablespoons of liquid soap with a gallon of water. We then poured it into a spray bottle and sprayed a small patch of our scallions that was affected by thrips tabaci.
The next day we turned on the overhead sprinklers to wash off the soapy residue.
To our surprise, the leaves had a pretty green color and were clean as a whistle. They started straightening up too — the curly leaves were almost completely gone.
Best of all, this homemade onion thrips control spray is cheap, so everyone can give it a try. Just be sure to use organic liquid soap if you have an organic garden.
7. Avoid Excessive Amounts of Nitrogen Fertilizer
You may not know it, but too much nitrogen fertilizer can actually encourage onion thrips infestations. So, it’s best to try and avoid excessive amounts.
8. Avoid Infected Transplants
The last thing you want to do is bring transplants that are already infected with these pests into your garden. That’s why it’s important to check any transplants you buy for signs of infestation.
9. Sticky Traps
You can also trap adult thrips using yellow or blue sticky cards placed near plants that are likely to get affected.
10. Bonide Captain Jack’s Orchard Spray
If you are searching for a natural pesticide to help with onion thrips, one product you should definitely consider is Bonide Captain Jack’s Orchard Spray.
This product is a natural fungicide and pesticide with sulfur and pyrethrin as its active ingredients.
This spray kills thrips. It’s also effective against aphids, leafminers, mites, whiteflies, and other foliage-feeding pests.
Takeaway
It’s important to develop an integrated approach that involves cultural, biological, and mechanical measures to keep onion thrips under control and prevent re-infestations.
Keeping a sharp eye out for these pests can help to reduce their numbers. Monitoring your crop regularly will help you note any problems before they become serious.
The natural remedies outlined above will help to keep your garden free of onion thrips and help you to have a better harvest.
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