- Controlling Whiteflies in Your Garden
- Making Your Own
- The Most Basic of Netting Frame
- Using Bamboo Lashed Together
- Frames Made from Hosepipe
- Discovering Balls
- Making Larger Wooden Structures
- Is a Curved or Straight Frame Best?
- Bought Are Better?
- Arched Mesh for Protection
- Metal Frames
- Kale Plant Protection: Tips For Pest And Kale Disease Prevention
- Kale Plant Protection
- Eliminating Kale Pests
- Kale Disease Prevention
- Common Kale Pests and How to Control Them
- Aphids (Aphididae family)
- Flea Beetles (Chrysomelidae family)
- Harlequin Bug (Murgantia histrionica)
- Imported Cabbage worm (Pieris rapae)
- Keeping Your Kale Plants Pest Free
- Home Remedies for Bugs on Kale Plants
- Plant Features
- Insecticidal Sprays
- Companion Planting
- How to Kill Whiteflies: Organic Control Tips
- What Whitefly Damage Looks Like
- Whitefly Predators
- Organic Whitefly Control
- More Advice on Organic Whitefly Control
- Controlling Whiteflies and Aphids
Controlling Whiteflies in Your Garden
Controlling Whiteflies in your Garden
All whiteflies suffer from an identity crisis, as they are not “true” flies at all. Their appearance resembles tiny, pure white “moths” but they are in fact, closely related to sap-sucking aphids. Aphid-cast skins can easily be mistaken for whitefly, but whitefly will quickly flutter up and fly away when disturbed.
Their quick flight pattern coupled with the fact that they hide on the underside of leaves make them difficult to control. Whiteflies are also prolific because their numbers increase from two to four, four becomes eight, eight becomes 16 and so on. During the hottest part of the summer, whiteflies may mature from the egg stage to an adult (ready to lay more eggs) in as few as 16 days.
Whiteflies can cause two types of damage to a plant. The first is considered to be “direct” damage. Whiteflies can seriously injure plants by sucking juices from them, causing leaves to yellow, shrivel, and drop prematurely. If the numbers of whiteflies per leaf are great enough, it could possibly lead to plant death. The second, which is known as “indirect” damage, is caused by the whitefly adults. They can transmit several viruses from diseased to healthy plants through their mouthparts. Whiteflies (just like aphids) excrete “honeydew,” a sweet substance that forms a sticky coating on leaves. The honeydew is soon colonized by a fungus called “sooty mold,” making leaves look black and dirty. Generally sooty mold is harmless except when it is extremely abundant and prevents light from reaching leaf surfaces, causing plants to become stressed. Sooty mold can easily be washed off with a forceful stream of water on sturdy plants.
Often times if there are high populations of whiteflies most likely there are also an abundance of ants present. Argentine ants love to feed on honeydew, and to ensure a continuing supply, they protect whiteflies from their natural enemies (beneficials).
Probably the most common whitefly in California is the greenhouse whitefly. It is distributed throughout the state and is commonly found in outdoor plantings, inside greenhouses, and occasionally on indoor houseplants. Whiteflies, like many insects, have immature (nymphs) and adult stages. Adults lay eggs randomly, in circles or arcs on the underside of leaves where they spend their entire life cycle. Whitefly nymphs have small, oval bodies and no wings and no apparent legs or antennae. The adults that emerge form mature nymphs are winged and look like a very tiny moth.
GIANT WHITEFLY Aleurodicus dugesii
The giant whitefly or Mexican whitefly has been moving into California and is making an unsightly mess of hibiscus and other landscape ornamentals. It was first discovered in San Diego County in 1992. It is now found in Southern California, parts of Arizona, Louisiana, Texas, and Florida. Giant whitefly gets its name from its large size relative to many other whitefly species. This species can be identified by spirals of wax which are deposited by adults as they walk on leaves. These deposits occur on both upper and lower leaf surfaces. Eggs are often laid amongst these waxy deposits. The nymphs produce long, hair-like filaments of wax up to 2 inches long. These filaments give a bearded appearance to affected leaves.
Avoid attractive host plants. Giant whitefly finds hibiscus, giant bird of paradise, orchid tree, banana, mulberry and certain varieties of citrus and avocados extremely attractive. If these plants are already in your existing landscape closely monitor the plants to detect early infestations. Control of this newly introduced pest will require early detection, rigorous sanitation, and washing off plants with a forceful stream of water (syringing).
- Learn to recognize beneficial insects. Among the most important natural enemies of whiteflies are the tiny parasitic wasps that lay their eggs inside the bodies of whiteflies. These tiny wasps cannot sting people.
- Attract beneficials to your garden by planting a wide variety of flowering plants or certain insectory plants (See article or fact sheet in this series called “Naturally Managing Pests… With a Healthy Garden”) can provide beneficial insects with the habitant they need (food and shelter). Natural enemies that attack many whiteflies are small birds, spiders, lacewings, ladybugs, and big eyed bugs.
- Inspect new plants carefully. Don’t purchase infected plants.
- Hang sticky traps above the plants at the beginning of the season to detect an invasion early.
- Use slow-release fertilizers. Maintain healthy plant growth, but do not over-fertilize with high nitrogen fertilizers. Too much nitrogen can overstimulate succulent plant growth, prompting some aphids to reproduce more quickly. Organic fertilizers are better because they slowly release moderate levels of nutrients.
- Avoid excessive pruning because it stimulates whitefly-attracting growth.
- Use a row cover (such as FastStart®) to exclude whitefly and other pests but allow air, light, and irrigation water to reach plants.
- Control ants by spraying or painting a 4” wide sticky barrier (such as Tanglefoot ®, Stickem ®, Tree Pest Barrier) around woody shrubs or trees. (See the Ant article or fact sheet in this series.) For many sensitive trees, such as citrus, a protective barrier of white latex paint should be appliedto the trunk before sticky barrier.
- Syringe undersides of leaves on sturdy plants with water to wash off whiteflies and honeydew. In University of California studies, side-by-side comparisons with several pesticides indicated that syringing performed as well or better than chemical treatments.
- Vacuum whiteflies in the early morning when they are cold and slow moving. This removes adults before they have a chance to lay more eggs. After vacuuming, empty the vacuum bag into a sealed plastic bag and removed from the property.
- Prune away severely infested portions of the plant. The removed material should be placed and sealed in plastic bags and removed from the property. Dispose of properly and do not compost.
- Purchase Beneficial insects. One tiny black ladybug Delphastus is a voracious feeder and can consume up to 150 whitefly eggs in a day. These extremely mobile, small black beetles are usually used in greenhouse environments. For outdoors, release the beetle under a row cover (like FastStart®) which will concentrate its efforts in that particular area. Another important predator and parasitoid of whiteflies is the tiny wasp Encarsia formosa. Encarsia wasps kill whitefly nymphs in one of two ways: they either lay an egg inside the nymph(which provides food for their young) or they kill the nymph right away and feed on it. Once the whitefly nymphs are parasitised they turn black and no longer feed.
- Use insecticidal soaps to kill whiteflies on contact while causing less harm to beneficial insects. Good coverage of the underside of leaves is essential for effective use. These products do not leave toxic residues, sparing injury to the natural enemies.
- Use spray (horticultural) oils to control whiteflies minimizing adverse effects on natural enemies
- Imidicloprid is a product that has come out recently, has proven to be very effective on whiteflies, and is low in toxicity. It is mixed with water and used as a drench on the base of the plants (use when your plant is rather thirsty) and the roots absorbs it up into the plant. It only has to be used annually. Follow manufacturers instructions.
- To protect bees, avoid applying imidacloprid during the period 1 month prior to or during bloom. Removing blossoms before they open on young trees will prevent honey bee exposure to imidacloprid in the nectar/pollen.
For more information:
The Ventura Certified Master Gardener Program, operated by the University of California Cooperative Extension, provides a free assistance Helpline and offers a variety of workshops, email at [email protected],edu or call us (805) 645-1455.
Check these websites:
- http://www. watoxics.org
Sources for Beneficial Insects:
- Buena BioSystems – 805/525-2525
- Rincon-Vitova Insectaries – 805/643-6267
- Tip Top Bio-Control – 805/445-9001
Q. Last year, whiteflies appeared for the first time and absolutely destroyed my vegetable garden. I went to a local nursery and spent a lot of money on products that did not work. The pests have come back this year and are destroying my garden again. I am desperate. What would you tell me to do?
- —William Rogers from McCalla, Alabama
Whiteflies are swarming on my eggplant, tomatoes, basil, tropical hibiscus, and even mint. I suspect they got to the hibiscus in the greenhouse this winter and then spread to my plants outside. Hope you have some ideas.
- —Bill Rogers in Oklahoma City, OK.
I have discovered white flies on my dahlias, and am very concerned. What do I do?
- —Pat in Groton, MA
What are the best ways to control whiteflies? They’re on most of my garden. I feed with Miracle Grow. I don’t have any mulch down yet, but plan on using some later this year.
- —Hubert in Houston, TX
A. Ah, yes-whiteflies; I remember them well-if not fondly.
We used to stage major exhibits at the Philadelphia Flower Show back when I was editor of ORGANIC GARDENING magazine. At the end of one, I took home some flowering tobacco (Nicotiana sylvestris) that we had used outside the Native American suburban home we had ‘imagined’ as being in an America where the Natives were never displaced by those original “illegal immigrants”.
The fragrant, shade-loving white tubular flowers looked lovely in my garden. The thousands of tiny white insects that flew into the air whenever I rustled up the leaves did not. I feared I had invited a Biblical plague to move in with me forever, but everyone said that the whiteflies would not be able to survive my winter. So, I tolerated them for the rest of the season, and as assured, never saw them again. I don’t miss them one bit.
My plants had originally become infested in a greenhouse. This is such a common origin that most sources use “Greenhouse Whitefly” as the common name of this pest. So, our Bill Rogers #2 is almost certainly correct in assuming they came into his garden via that hibiscus. Probably the same story with those dahlias, as they would have to have been over-wintered indoors up in chilly ol’ Maine. Yet another reason to quarantine and carefully wash all plants before bringing them into your horticultural day care center.
Although considered by virtually all experts to be more of a nuisance than anything else, large numbers of whiteflies can stress the plants they infest. The biggest problem is that their sap-sucking can transmit diseases. And their black, sooty “honeydew” (how’s THAT for a euphemism? I may never call my wife “honey” again!) can make a big mess.
‘Houston Hubert’ has the most to worry about here as his area rarely freezes, making these pests a possibly perennial problem. So, Hubie: No more Miracle-Grow or other chemical fertilizers; the fast, weak growth you get from these wretched things attracts these pests like mad. Build up your soil with lots of compost and other organic matter, get a nice non-wood-based mulch down, and invest in yellow sticky traps.
Whiteflies can’t resist the color yellow, and so most garden centers and catalogs sell packaged yellow sticky traps for houseplant and greenhouse protection. These are great for all indoor situations, and even for a few potted plants outside. But if you need to protect large areas outdoors, you might want to make your own bigger ones. Paint sheets of plastic or cardboard bright lemon yellow and coat them with an “insect trapping adhesive” (sticky stuff), like Tanglefoot. Hang the traps around the affected plants and the adults will get stuck to them.
Now, you have to replace the traps when they become full of felons, so it’s best to try and knock the population down a bit first. One way is to have a helper disturb the plants while you suck the flying hordes into a canister vacuum or Shop-Vac. Don’t laugh; giant vacuums were being used for pest control on Texas farms just a few years after the home version was invented.
Or use a spray to reduce the population before you put your traps in place. Many gardeners write in saying they’ve found sprays of all kinds to be ineffective against this pest, but that’s often because they’re spraying the wrong part of the plant. They’re hitting the part that they can see, the tops of the leaves. But whitefly adults and nymphs-and the next generation’s eggs-spend virtually all their time on the undersides of leaves. So spray that hidden area well with insecticidal soap or a light ‘summer spray’ (vegetable-based) horticultural oil; this will smother the eggs and nymphs, and maybe get some of the adults. (See the question below for the USDA’s ‘home made’ whitefly spray recipe, combining soap and oil.)
Now these creatures reproduce fast; the eggs hatch in just a few days and every time a bell rings, a whitefly nymph gets its wings (or a couple of weeks after it hatches, whichever comes first). That makes weekly sprays a good idea, especially early in the season, before their numbers get out of hand. You can also spray the plants preventatively next Spring with a garlic-based repellant or Neem, a natural pesticide that also inhibits feeding.
Q. Mike: I have a small nursery in the basement of our house. It appears that somewhite flies came in with my spider plants and vines for the winter. What is your recommendation? And what is the correct ratio of soap to water for spraying? Thanks,
- —Ed in Green Lane, Pa.
A. In indoor situations, your main weapons are yellow sticky traps and beneficial insects. Two exceptional whitefly foes are sold for greenhouse use; a specialized ladybug and a tiny parasitic wasp, Encarsia formosa. If the infestation is outdoors, you’ll get better results by attracting native beneficials to prey on the pests. (To learn how, see this previous Question of the Week on attracting beneficial insects.)
And I generally recommend that people buy packaged insecticidal soap instead of trying to make their own; there is often a VERY fine line between creating a helpful spray and an unfortunate herbicide with home-made. But USDA researchers have come up with a ‘home remedy’ specifically for use against whiteflies that seems worth passing along:
Add one tablespoon of liquid dishwashing soap (the regular kind; NOT one of these awful anti-microbial things) to a cup of vegetable oil (peanut, corn, soybean, sunflower or safflower) and shake well. DON’T USE THIS AS YOUR SPRAY; IT MUST BE DILUTED! Mix two tablespoons of this ‘master solution’ into a cup of water, shake well and spray on those infested undersides.
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Making Your Own
Most garden netting requires some kind of frame. Knowing which ones that will work best can be a nightmare when you are starting out. If you look around at the other allotments it will give you ideas but will not help as they are usually all different.
When I was asking which type of netting would be best I was given the best advice I could have been, although it didn’t feel like it at the time. They simply said that I would find what was right for me over time.
This did not answer any of my questions like: What size should I get? Should I have curved or straight? Is bamboo better than metal? Which is easiest? And much more.
So I will say the same to you. You will discover what is best for you in time. For each person it is different. You do need a net, however, unless you want your plants taken out!
I will however also give you some ideas based on my experience, research and observations so that you can make a more informed decision early on.
The Most Basic of Netting Frame
The most basic frame I have seen is simply net resting over some thick sticks and tied down on each side. This is cheap and easy to do. Although it may not suit all plants.
Using Bamboo Lashed Together
Basing my netting plans on my neighbour’s beautiful and easy to get into frames but without the budget, my first attempts were quite elaborate. I lashed together bamboo using nothing more than ties twisted around them.
A huge fame that took up most of one side of the allotment. This was designed so that all I had to do was untwist a couple of the ties and I could get into it and garden with ease.
Good plan. But it failed. What I didn’t take into account was the nets tendency to get tangled in everything around it or its movement in the wind. It had small barbs as well so that when I moved it back it caught in itself. Argh!
In my defence, it withstood the winter storms.
There is no reason why you cannot simply lash bamboo together to create a frame and put the net over it. Alternatively, you could create each frame side complete with a net then lash the frames together.
Or you can use connectors to connect your bamboo more smoothly.
Selections GFA662 Bamboo Cane Flexible Connectors (Set of 10)
Frames Made from Hosepipe
Still basing my plans on my neighbour’s bought version I tried again. This time I used a hosepipe. This is not bad in itself but my hosepipe wasn’t stiff enough. You really need the strong blue pipe that doesn’t bend.
I stuffed bamboo up it and put that into the ground. I also had wire. The intention was that I could slide the netting up and down the wire for easy access and that it would not tangle.
Making A Strong Structure from Hosepipe
The way most people do this is to make a wooden base the size needed then to staple the curved pipe along it. Finally, they put over the net and staple that to it as well. This creates a permanent structure that fits over your beds and that can be moved when you want to.
The disadvantage of this is you have to lift the whole thing up to get to weed or get your produce.
I love netting balls. Simple things and all that. My sister finally found some in the Range and bought them for me. All you do is pop a bamboo into each corner (use extra for a longer bed) pop the balls onto the top and you have your frame. Pop the netting over the top and pin it down. Done.
Out of all the netting (including the bought), this has been the fastest and easiest to put up and also to use. Also, the cost is relatively small if you are starting out and either don’t want to or can’t invest a lot in your netting.
Alternatives: Some people use old tennis balls.
Making Larger Wooden Structures
Some people have much larger structures. These are all sizes right up to walk in frames for fruit. These are made from wood. Often recycled bits rather than bought. These are then joined together to make a box. The corners are strengthened with diagonals.
The box frame is then covered either in normal plastic netting or chicken wire.
The advantage is it is more sturdy and will last longer. It is cheap to make.
The disadvantages are that larger structures are more suited to crops that do not rotate as you will have to move them each year. Also, you will need basic DIY skills and tools to make them.
I have seen people with these covering brassicas and while they do keep off the birds they do not keep out the cabbage white (but then neither does netting!)
Is a Curved or Straight Frame Best?
I like curved simply because I like the shape better. However, plants grow up and out. A curved structure goes up and in. A lot of people use them, however, this needs to be noted when thinking about what you are going to use as it can limit growth depending on the size of the surround.
Bought Are Better?
I have a bought frame for my established fruit bushes. It simply stays there all year and I removed the net after fruiting. The advantage is that it is quite large and you can walk into it to collect the fruit. The disadvantage is also that it is large. Believe it or not, the wind took the frame and threw it across several allotments, hence the binding down one side.
Bought frames can be a considerable investment. If you are new and not sure if this is for you yet then it is probably better to stay clear of a bought frame until you are sure.
They are stronger and last longer than the temporary bamboo ones.
Arched Mesh for Protection
This is where my neighbour’s protection comes in. She has four beautiful arched mesh covers that she uses. Although technically a cloche, the protection is similar. The cost was around £84 each. When she wants something she just unzips them. Sigh. Now these are not so much net as mesh, which is better as the cabbage white cannot get through. The mesh does let rain water through. There is also a fleece cover that can be used to keep plants warm in spring. They are easy and fast to put up if you take them down and can be transported from bed to bed.
The disadvantage is the initial cost. If you have something that does require insects you will need to unzip them. Also again they are quite large and my neighbour found hers strewn across other allotments last winter. You have to have the size that is for sale and not your own size.
Gardman 3 x 2 x 2m Large Fruit Cage
Fruit cages come in all sizes and are not only great for fruit but also on other beds or square foot gardening.
Fruit cages tend to be 6 foot high to allow you to get in to pick the fruit. Although of course, you can use shorter ones if you prefer.
They are great because you have a solid structure that is designed not to rust that you can apply different kinds of netting to.
It is easier to attach your net to the solid frame than a crossed bamboo one.
It is a good idea to pin them to the ground to help prevent movement.
Easy Access Tip: If you use clamps on your net down one side you can undo them for quick and easy access.
Saving Money Tip: My sister discovered this. She bought a fruit frame for her veg bed when it was on offer. Then she got a larger bed. She inserted a bamboo cane between the two metal ones to extend the length of the frame. It bends a bit in the middle and is not quite so strong but it does the job and saved her buying a bigger one.
These are pretty much the same as for fruit however they tend to be only 4 foot high which is more than enough height for most vegetables. The lower height also reduces the cost.
Vegetable Cage – 4ft high x 4ft wide x 6ft long
You can tell how long an allotment holder has been around by the amount of netting about. New to the game and you may be offered a scrap as an incentive by a neighbour. Hang around a bit and your plot will be covered in barricades: fruit and brassica cages, floating covers, old fireguards, scaffolding and upcycled furniture. This is not an aesthetic look: it says, “I want supper more than anything else.”
Whether it is pigeons, deer, rabbits, squirrels or badgers, the most effective defence is netting (scarers rarely work). You can confuse a few creatures with unpredictable planting; pigeons are useless at finding cabbages among flowers, for instance, but come winter, once the garden is stripped back, it’s a free-for-all.
A cage must be strong; sturdy enough to withstand snowfall, winds and the trampolining of angry squirrels. If it protects a large space you need to be able to stand up in it – crawling about is a bore and it will quickly become weedy.
Money is best spent on netting – supports can be fashioned out of numerous materials. Good netting is made from polyethylene. It comes on and off easily, does not tear and is easy to repair. You can get flexible stuff or a stiffened version (better at keeping deer out). Cheap green netting will tangle into a mess that drives you near mad and after a season will rip at the slightest snag.
It is distressing to find a trapped bird or slowworm tangled into a muddle, so make sure there are no gaps. Electrical ties secure netting quickly and easily, and tent pegs keep the bottoms safe. Otherwise, dig a channel and bury the bottom so rodents can’t get in (they are particularly fond of strawberries). Once fruit has been picked, remove netting to allow in insect-eating birds, an essential pest control, and pollinating insects to set fruit.
I cover my small raised beds with enviromesh. This fine-weaved plastic netting is not cheap, but is strong and lasts for ages. It is fine enough to keep off small insects such as butterflies, carrot fly, flea beetles and leaf miners, and yet durable enough to keep pigeons off. It is also good frost and wind protection.
I drape the netting over the crop, perhaps with a hazel stake or two, weighing down the edges with bricks or soil, so it is easy to get into for harvesting and weeding.
If you are reading this and aren’t the gardener, take note: netting may not seem a romantic Christmas present, but believe me when I say a great roll of mesh would make a fair few gardeners’ hearts sing.
Kale Plant Protection: Tips For Pest And Kale Disease Prevention
Kale plant protection for next year’s crop begins after the fall harvest. Many insects that damage kale, spread diseases overwinter in plant debris left in the garden at the end of the season. Fall cleanup, including disposal of plant debris and turning the soil to expose insects goes a long way toward preventing problems in the spring.
Kale Plant Protection
Another fall project to foil diseases of kale is working compost into the soil. Most people know that compost is a great natural fertilizer, but did you know that it also helps the soil drain freely? Soil that can’t drain freely stays wet too long, and many fungi thrive in wet soil. Working in compost in fall allows it plenty of time to combine with the soil so that it is ready to manage water more efficiently in spring.
Kale pests also overwinter in garden debris and soil. Expose the insects to the harsh conditions at the surface soil by turning the soil several times over fall and winter.
Eliminating Kale Pests
Identifying and eliminating some of the most common kale pests can go a long way in your kale plant protection program. Common garden pests affecting kale include:
- Aphids – Allow natural predator insects to do as much of the work of controlling these insects as possible. If you must use an insecticide, use a soap-based product or neem oil. You may have to spray several times.
- Flea beetles – Good fall cleanup and regular weed removal are your best bets in controlling these insects, which chew tiny holes in the leaves. If these kale pests find their way to your plants anyway, choose an insecticide labeled for use against flea beetles and make sure the label states the product is safe to use on kale.
- Caterpillars – You’ll probably notice moths darting around the plant before you see the caterpillars. In most cases, you can hand pick them. In severe cases, or if you can’t bear to touch the pests, you can use Bacillus thuringiensis (Bt).
- Whiteflies – These tiny, whiteflying insects rise in a cloud above the plant. Use insecticidal soap or neem oil and spray every few days until they are gone.
Kale Disease Prevention
Starting a kale disease prevention program will help eliminate most diseases of kale in the garden. Begin protecting kale plants by implementing these control measures:
- Water the soil rather than the plant. Wet plants are more susceptible to diseases than dry ones.
Also, avoid splashing soil onto the plants when you water.
- Clean tools thoroughly before moving from one part of the garden to another. Don’t forget to clean your shoes! Bits of soil that travel from one part of the garden to another on the soles of your shoes may carry disease organisms.
- If you think your kale is infected with a disease, cut back on high-nitrogen fertilizers until you have the problem under control.
- Fungicides containing copper may help prevent disease infection or slow its progress, but they don’t cure diseases. By using fungicides early, you may be able to hold off the disease until after you harvest your crop.
Now that you know more about protecting your plants from diseases and garden pests affecting kale, you can enjoy a new crop each year without any worries.
When insects attack your kale plants, you’ll want to fight back. Fortunately, there are natural ways to kill the many different insect pests that plague these greens.
Once I’ve planted my kale and watched the leaves grow, I’m not exactly thrilled to see big chewed holes or lots of little bites. But I realize this is just a part of gardening.
The first thing to do when you spot insect damage on your kale is to identify the pest that’s causing it. Even if you don’t see the bug itself, the type of bites on the leaves can serve as clues.
Common Kale Pests and How to Control Them
- Aphids (Aphididae Family)
- Flea Beetles (Chrysomelidae Family)
- Harlequin Bug (Murgantia histrionica)
- Imported Cabbage worm (Pieris rapae)
- Keeping Your Kale Plants Pest Free
Continue reading to learn more about pest identification and control.
Aphids (Aphididae family)
Aphids are a family of small insects with soft bodies and sucking mouthparts. Large groups of aphids often appear on kale plants, causing a fuzzy or spotted appearance.
The bugs themselves suck the juices out of the plant, which can lead to discolored leaves. Aphids also produce a sticky substance called honeydew, which can cause the growth of fungus.
If there are just a few aphids on your plants, you can spray them off with a hose, or remove them by hand. Remove and discard leaves infested with or damaged by aphids. You can place these in your compost pile.
If you have a large infestation of aphids, one option is to release ladybugs. These beneficial insects eat up aphids in great numbers. However, you’ll need to release a large number of ladybugs for effective control.
Another helpful insect in the fight against aphids is the parasitic wasp Aphelinus abdominalis. This wasp doesn’t just eat the pests, it lays its eggs in living aphids.
When the eggs hatch into larvae, the aphids die and turn into a dry shell known as a mummy. Once they mature, the adult parasitic wasp chews a hole in the mummy and emerges – ready to do battle with more aphids!
A. abdominalis can be introduced to your garden when they are in the larval stage – inside the mummy. You can buy 250 of these hungry beneficial insects from Arbico Organics, and watch them destroy your aphid population!
Since aphids have soft bodies, they can be controlled effectively by spraying with neem oil. Neem oil is made from the seeds of the neem tree.
To use neem oil, dilute it according to product instructions, and spray it on your kale plants. It is best to reapply neem oil every seven days. While you can use it up to the day you harvest, you don’t want to ingest it directly. It’s worth noting that neem oil can be toxic to bees.
Insecticidal soaps can also be used to kill aphids. Check the label carefully to make sure it’s suitable for edible crops and pay attention to how close to harvest you can safely spray.
The best time to apply insecticidal soap is in the morning or evening, when the temperatures are cooler. You should avoid spraying kale in sunny conditions, as this can burn the leaves and damage to your plants.
You can read more about aphid control here.
Flea Beetles (Chrysomelidae family)
These little beetles like to chomp on your kale, leaving tiny pits and holes in the leaves.
Although these beetles are small, they often arrive in large numbers, and can do a lot of damage.
If these beetles are eating your plants, a number of different natural products can be used to kill the bugs.
Diatomaceous earth (DE) is a powder made from fossilized remains of tiny organisms called diatoms.
This substance is sharp on a microscopic level, and damaging to the respiratory systems and mucous membranes of a variety of destructive insects such as flea beetles. But it is harmless to larger creatures such as humans and dogs.
Once you sprinkle DE on your plants, the flea beetles will die. Make sure you only use food grade DE near kale and other edible plants.
Pyrethrins are broad spectrum insecticides comprised of compounds derived from flowers in the Chrysanthemum genus. Products containing pyrethrins kill a variety of insects, including flea beetles.
To use, spray your product of choice on your kale plants, these compounds work by affecting insects’ nervous systems, and products quickly kill pests.
Another natural insecticide that kills beetles is spinosad. This compound is derived from soil-dwelling bacteria.
It can kill pests on contact, but it is more effective when ingested. After you spray your plants with spinosad, flea beetles will die within two days.
Neem oil another option that may be used to treat flea beetles.
Harlequin Bug (Murgantia histrionica)
Harlequin bugs are shield shaped, with either black and red or black and yellow markings. They lay their black and white eggs in bands of six on the undersides of leaves.
These bugs have sucking mouthparts that they use to drink the sap from leaves. This results in white spots known as stipples. If an infestation becomes large enough, plants can turn brown and wilt.
Small numbers of the bugs can be controlled by picking off adults and eggs, and placing them in soapy water.
Harlequin bugs can also be controlled with sprays of neem oil, pyrethrin, or spinosad.
Insecticidal soaps can be used to help control harlequin bugs as well. They don’t actually kill the bugs, but they can soften their shells so other insecticides will become more effective.
Imported Cabbage worm (Pieris rapae)
The imported cabbage worm is the juvenile stage of a small white butterfly sometimes called a cabbage white. These green caterpillars can quickly devour kale leaves if they’re not properly controlled.
Signs of cabbage worms include large bite marks or edges of the plants missing. Other signs include round green frass, or feces – these things eat a lot, and it shows!
If you notice these worms, one way to control them is to physically remove them from your plants. Simply pick off the worms and egg masses, and place them in a container filled with soapy water.
Another control method is to use the bacterial insecticide Bacillus thuringiensis kurstaki (Btk). After you spray this bacteria on your plants, the insects will ingest the product and die. A variety of Btk products are available from Arbico Organics.
Crops can usually be harvested the day after application, but remember to always check the label if you spray edible plants with this product.
Keeping Your Kale Plants Pest Free
Chances are, your plants will be attacked by some type of bug at some point in their life. Fortunately for you, now you know how to naturally kill some of these major pests!
Let us know in the comments if you are having trouble controlling pests on your leafy greens, and what methods you use to deal with them.
For more information about planting, growing, and harvesting kale, try these suggestions for further reading:
- What Causes Yellowing and Thinning of Kale Leaves
- How to Keep Kale from Wilting in the Garden
- 6 Best Types of Kale for Cold Climates
Ask the Experts, LLC. ALL RIGHTS RESERVED. See our TOS for more details. Uncredited photos: . Additional writing and editing by Clare Groom and Allison Sidhu.
About Briana Yablonski
Briana Yablonski grew up in Eastern Pennsylvania and currently resides in Knoxville, Tennessee. She holds a Bachelor of Science degree in plant sciences and has worked on farms in Minnesota, Pennsylvania, Virginia, and Tennessee. Now, she spends many hours planting seeds and moving compost at her market garden. When she’s not immersed in the world of gardening, Briana enjoys walking dogs at the local shelter and riding her bike. She believes that gardening fosters curiosity, continuous learning, and wonder.
Home Remedies for Bugs on Kale Plants
Kale is a cold-hardy, leafy green well-suited to life in cooler climates. While kale is a relatively low-maintenance crop that draws few serious pests, from time to time insects may invade a particularly lush plot. Fortunately, there are several easy home remedies that effectively remove insect pests while posing no threat to children, pets or plants.
A cool-season vegetable, kale does best when planted in the early spring or late fall as it tends to bolt in hot weather. This tasty salad green can even survive light snows, allowing gardeners as far north as USDA Hardiness Zone 5 to harvest fresh vegetables all winter long. This preference for cold weather helps keep kale pests to a minimum, although insects such as aphids, cabbage loopers, leafhoppers and flea beetles can occasionally become a problem.
Homemade insect sprays keep pests under control by coating visible bugs and vulnerable kale foliage with slippery soaps and pungent spices. To make a basic bug spray, simply stir 2 tbsp. of liquid detergent into 1 gallon of water and apply the solution to any affected plants. The surfactants in the detergent clog the insects’ breathing apparatus and smother them. Create a longer-lasting repellent by adding a few tablespoons of garlic, onion powder, red pepper or hot sauce to the soapy water before spraying it on the plants. The spicy flavor and strong scent will keep many unwanted pests at bay.
While sprays are convenient, inexpensive and simple to make, they must be reapplied regularly to be fully effective. Well-chosen companion plants can ward off unwanted pests all season long. Highly aromatic herbs such as lavender or basil grow well when planted next to kale. Not only does their color and texture contrast nicely with the leafy greens, their fragrant foliage is naturally repellent to many pests. Alternatively, flowers such as marigolds can lure beneficial insects into the garden to prey on harmful bugs, reducing the need for chemical pesticides.
Fresh, young kale leaves can also be protected from pests with physical barriers such as floating row covers or mesh netting. When these lightweight, translucent fabrics are draped over the plants, they shield the foliage from the outside world. The material allows the kale to receive both sunlight and water, but the fabric blocks access to the leaves.
How to Kill Whiteflies: Organic Control Tips
What Whitefly Damage Looks Like
Pale, wilting leaves are a sign that whiteflies are sucking juices from leaf undersides. As you approach infested plants to inspect the lower sides of wilted leaves, hundreds of tiny white moths take to the air in a cloud. If the whiteflies have been feeding for several days, the leaves may have a sticky substance (whitefly honeydew) and ants may be present as honeydew consumers.
Whiteflies are greenhouse pests in all climates, but they are serious vegetable garden pests mostly in mild winter climates that permit their winter survival. When adult females find suitable host plants, they feed on leaf undersides and lay eggs there. A female may lay 200 to 400 eggs without moving from a plant. Upon hatching, the nearly invisibly small crawlers find a place to feed and insert their sucking mouthparts. Feeding continues for up to three weeks, when nymphs pupate into adults. Frequently problems are not noticed until a 30-day generation has passed, and a population has successfully flourished in the garden.
Diversified organic gardens that include plenty of flowers are poor whitefly habitats because they include such an abundance of natural predators, including lacewing larvae, lady beetles, and predatory bugs. In greenhouses, imported Encarsia spp. parasites are often used to control whiteflies, but they tend to disperse too widely when used outdoors.
Organic Whitefly Control
- Aluminum reflective mulch repels whiteflies by making it difficult for them to find host plants. This is a good way to protect tomatoes and peppers from diseases spread by whiteflies.
- Use yellow sticky traps to monitor or collect whiteflies lurking among tomatoes, peppers, sweet potatoes or cabbage family crops. A half-and-half mixture of petroleum jelly and dishwashing detergent, spread over small boards painted bright yellow, is sticky enough to catch little whiteflies.
- Blast whiteflies from leaf undersides with a strong jet of water. Then apply a weak solution of insecticidal soap, preferably late in the afternoon. Repeat after one week.
- A small vacuum is the best way to remove whiteflies from plants because it will remove both nymphs and larvae. If you have chickens, allow them to peck through infested plant foliage before you compost it.
- Never use chemical insecticides in attempt to control whiteflies. Many strains are pesticide-resistant, but their predators are not. You may accidentally kill many beneficial insects, and the whiteflies will bounce right back.
More Advice on Organic Whitefly Control
Gardens that host an abundance of beneficial insects make poor homes for whiteflies. In areas where whiteflies are common and your neighbors use a lot of pesticides, monitor populations with sticky traps and use a vacuum to keep small outbreaks under control. In seasons following whitefly problems, avoid planting attractive annuals such as lantana, salvia and hibiscus.
More information on organic whitefly control is available from the University of California, Mississippi State University and the University of Missouri.
Controlling Whiteflies and Aphids
Few insect pests are more widespread than whiteflies and aphids. They attack indoor and outdoor vegetables, flowers, herbs, shrubs, and trees. They breed quickly, and once their numbers are high, they can damage leaves, stems, fruits, and even roots by sucking plant juices. Let’s look at both pests and the safest controls for them.
Tools and Materials
- Yellow sticky traps
- Insecticidal spray: soap, horticultural oil, neem
- Hand sprayer
An aphid’s life. Aphids like the low light levels and cool conditions of spring and fall. They will attack all plant parts but prefer young, succulent growth. There are many species of aphids, some named after the plants they attack, such as pea aphids and peach aphids. In general, all are small (1/16 to 1/4 inch long) and oval-shaped, and can be black, white, green, or pink. Although most aren’t very mobile, some forms have wings. All reproduce quickly, and under the right conditions a small number can bloom into a major infestation in no time. By sucking plant juices from leaves and stems, they weaken the plant. More seriously, they can transmit virus diseases that gradually debilitate and kill some plants.
A whitefly’s life. In cold-winter climates, whiteflies are mostly greenhouse or indoor pests, but they can be found in the garden. In mild-winter climates with no winter cold to kill them, whiteflies are serious outdoor pests. In recent years in the Southwest, pests such as the silverleaf whitefly have been among the most damaging to agriculture.
Adult whiteflies hide and feed on the undersides of leaves. They are most noticeable when you rustle the leaves and a cloud of tiny white specks emerges into the air like “plant dandruff,” as some gardeners aptly describe them.
Like aphids, whiteflies reproduce quickly, laying white eggs that hatch into white crawlers on the undersides of leaves. Whiteflies thrive in sunny, warm conditions. The crawlers and adult flies suck plant juices, weakening the plants.
Aphid and whitefly controls. The first line of defense is prevention. Check plants regularly. Avoid high-nitrogen fertilizers, which create young, succulent growth which these insects love. Isolate infested plants from others and control the pests aggressively.
For whiteflies, hang yellow traps coated with a sticky substance close to the tops of plants. Whiteflies are attracted to the color yellow, and once they land will be stuck and die. Hand-crush small populations of young aphids and whiteflies. Encourage natural enemies in the garden, such as ladybugs and lacewings, by planting diversity of plants and not spraying pesticides. As a last resort, use low-toxic sprays such as insecticidal soap, horticultural oil, and neem to reduce populations before they get out of hand. Repeat treatments every few days until the problem is under control.
Aphids can easily be removed from a plant by knocking them off with a stream of water from a hose. Once off, they tend not to climb back up.
To control small populations of whiteflies on houseplants, approach them in early morning and evening when they are most sluggish. Use a vacuum cleaner set on low suction to remove the whiteflies.
Photography by Suzanne DeJohn/National Gardening Association.