Tips for Getting Rid of Whiteflies in the Garden
Here at J&R Pierce Family Farm, I think it’s important to connect my readers with valuable insight from other experts. Today’s post is a guest post brought to you by Zach Vesperi.
Looking for tips for getting rid of whiteflies? You’ve come to the right place.
In fields and gardens across the globe, every horticulturist will at some point deal with pest control.
Whether you are a seasoned gardener or new to plant care, nature, in many ways, will seek to reclaim your beloved plants in one way or another. There are a host of issues we have to address in raising plants in captivity.
Weather and soil quality are obvious, but the ever-present problem of pest insects degrades your plants in very frustrating ways.
One of the most common (and hardest to deal with) pests, and especially for vegetables and ornamental plants, is the Aleyrodidae family, more commonly known as whiteflies.
These insects, not actually flies despite their name, are related to aphids and are the bane of gardeners the world over.
Whiteflies are very small and their size makes them hard to keep away from plants as they can slip through even fine mesh coverings. Their resistance to pesticides is also an issue in containing or removing infestation. They tend to arrive and if not dealt with swiftly, can overtake your plant and kill it rather quickly.
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What Causes Whiteflies in the Garden?
Whiteflies can appear at any time and in any garden, but your odds of a whitefly infestation are higher if:
You brought in infested greenhouse plants or produce
You don’t regularly inspect the undersides of your plants’ leaves
There are certain ornamentals that attract whiteflies, like hibiscus plants and mulberry trees, growing in your garden
You’ve used too much nitrogen-based fertilizer
The plants are drought-stressed or suffering from a disease
Want to learn more about whiteflies? Check out this video below:
What Is A Whitefly And Why Should I Worry About Them?
Trialeurodes vaporarioru, or the greenhouse whitefly, is the main culprit you will find.
The entire family, comprising almost 1600 species, is closely related to aphids, which are another garden pest you may be more familiar with.
They are not true flies, and come in a variety of shapes and sizes, and generally have bodies measuring 1-2mm with <3mm wingspan. Their name stems from the prevalence of white colored wings found in several species. They thrive in warm weather and especially in greenhouses.
Whiteflies are found all over the globe, and cause massive amounts of crop damage regardless of the location. They are extremely hardy insects; once established, infestations are extremely difficult to deter.
Whiteflies lay their eggs on the underside of plants, and once hatched immediately begin feeding on the plant sap. Whitefly offspring continue depleting the plant at each stage of larval development until they reach full maturity and begin laying eggs of their own. Whiteflies are very good at what they do, and what they do is wreck your plants.
How Do Whiteflies Harm Plants?
Whiteflies feed on the sap of the host plant by puncturing the outer membrane of leaves with a set of “stylets,” mouthparts which are extremely thin and like needles (think similar to a mosquito).
They pierce into the phloem, tissues that contain sap, which transports nourishment from root to new growth.
Because of their target, they typically attack the part of the plant with the most nutrients, meaning the lower portion of the plant.
This act in itself is destructive to the plant, causing malnutrition through an increasing lack of essential nutrients.
As they penetrate the phloem, the whitefly excretes a sugar-rich and sticky liquid called honeydew, due to the pressure of the sap escaping the plant. The removal of vital plant sap is a killer, along with the residual honeydew that is hard to remove and supports outbreaks of sooty mold.
Sooty mold is a fungus that by itself is not lethal to the plant, but rather an indicator of possible pest infestation.
The combination of factors causes leaves to deteriorate, turn yellow and drop from the plant, accelerating the death of the whole plant.
Tips To Get Rid Of Whiteflies On Plants
So you’ve discovered a handful of little white bugs flying around your garden, and you’ve checked your plants and seen a few eggs here and there. You know that where whiteflies flourish, more are on the way.
This is the time to act.
What do you do?
This very question is one that is the most difficult to answer, but you are not alone and there are some tricks of the trade to rid your plants of this pest.
Not all will work with 100% success, but you can keep the population at bay long enough to address the issue with luck and determination. Here are some tips to start you off.
1. Use Natural Predators
Whiteflies are hard for us to control, but they are not impervious to the laws of nature. You can utilize predatory insects to help regulate the population before it explodes. There are many retailers that specialize in sales.
Keep in mind that these insects are themselves not at the top of the food chain and can become attractive to larger pest animals. Keep this in mind when releasing them. Some of the born enemies of whiteflies include:
Ladybugs – these feed on whitefly eggs (among others) and are generally considered a good garden insect. These can be used indoors as well.
Lacewing larvae – these also feed on whitefly eggs as well as a list of larger pest insects.
Whitefly Parasites - Encarsia Formosa and Eretmocera Eremicus – these tiny non-biting wasps earn their namesake. The former species is typically used in a wider variety of settings, with the latter being more effective in high temperature areas. Females attack and lay eggs inside the bodies of nymph whiteflies (up to 200 per week each) and the young wasp will hatch and eat its way out through the body, killing its host. Releasing these wasps is a well-established option for whitefly control.
Entomopathogenic Fungus - Beauveria Bassiana – while a mouthful to pronounce, this is a naturally occurring fungus that acts as a parasite, infecting and overtaking its host. This particular fungus attacks whiteflies from egg to adult and all stages in between. Once spores have taken hold in the insect, the fungus quickly grows inside and feeds on the nutrients present in the host’s body, producing toxins and killing the host insect. The cause of death is called White Muscardine Disease. The deceased host becomes hardened and B. Bassiana covers the host in white mold which produces additional spores
2. Clean Individual Plants
This is a largely time-consuming and minimally effective tactic, but when dealing with a tenacious pest such as whiteflies, you need to be prepared to try anything. Here are some cleaning tips.
Simply spraying the plants with a water hose can disperse a fair amount of whiteflies and their young. Spraying a homemade solution of dish detergent and water can disperse smaller populations of whiteflies.
Wiping down the top and underside of leaves and clear adults and nymphs alike.
If all else fails, you can try using a handheld vacuum to remove whiteflies. Just be sure to empty the reservoir outside your house and away from your plants!
3. Try Traps, Insecticides, and Pesticides
Whiteflies are extremely hardy creatures given their diminutive size, and have been discovered to actually resist many weaker pesticides and often only those whiteflies which have been sprayed directly will be killed.
But not all is lost, and there are some more aggressive measures you can take to depopulate. Try these:
Basic sticky traps (commonly used for other pests as well) are an option, but only effective against airborne whiteflies. Obviously, the only individuals affected will be adults, therefore preventing them from laying more eggs. Traps will not have any effect on eggs, nymphs, or young adults. Hang them as close to the infestation as possible to ensure the highest number of adults are captured. More useful for detecting infestation than controlling it.
Soap or oil-based sprays are only effective on the whiteflies sprayed directly. Neem oil is used as an especially revered spray in this regard. Plants will have to be completely covered in order to maximize effectiveness, particularly the underside and lower leaves, as these are the most common areas for infestation to develop. Use sprays at dawn or dusk to reduce “burn” from sunlight, as the liquid will magnify UV and damage your plants.
Highly toxic pesticides will wreak havoc on your plant, whitefly predators, and pollinators. Whitefly infestations can even build resistance to these sprays, creating a rather ironic reversal of outcome. Avoid this tactic.
4. Try Other Preventative Measures
There are some products on the market that can help you to deter whiteflies from making themselves at home in your beloved plants.
Plenty of time, thought, and effort, going back a long time, has gone into suppressing whitefly infestation. They are simply difficult to keep out! Give these ideas a try:
Reflective mulch - this is one of the more recent, cutting edge methods of deterrence. Several studies have been conducted using this material, and it has been established to reduce the appearance of whiteflies. You can purchase mulch infused with aluminum or silver polyethylene, which reflects the maximum amount of sunlight to the underside of leaves. Whiteflies are confused by the intense light and have more difficulty locating their desired egg-laying areas.
Superfine mesh netting – many species of whitefly are so small that they can fit through the openings in the most common garden mesh netting you can find, while their natural enemies are kept out by their size. Because of this, netting is not generally the most effective measure, but again, if you are serious about ridding your plants of these pests, you must try anything. It is best used in combination with other prevention solutions. The smallest grade of mesh will block sunlight and beneficial bugs from accessing the plant, and young whiteflies can still enter. But you may be able to slow the infestation enough to get a handle on the population before it explodes.
5. Remove Host Plants
A bolder and more productive method, while not typically the ideal, is to simply remove the infested plant altogether.
If whiteflies have appeared in a particular area of soil or on specific plants themselves, you should isolate the primary host plant.
You may be able to then focus more effort simultaneously on the less afflicted plants as well as a more concentrated approach to the worst case.
Keep in mind, you may not be able to salvage this isolated plant, but that is better than losing an entire group!
6. Be Vigilant With Inspection and Watering
The simplest way to spot and clear newer infestations is to visually inspect each plant and generously spray with as high pressure water as your plants can withstand.
You don’t want to damage the leaves or overwater, but clearing leaves of eggs and nymphs is a good way to get ahead of impending nests.
Need help staying on top of your gardening schedule? This garden planning chart will help you make quick work of everything you need to do!
What Causes a Whitefly Infestation?
There are several factors at play when it comes to a whitefly infestation.
The types of plants afflicted, the weather in your area, the health of your plants, the prevalence of pre-existing whiteflies in the area, and more. Here are the most common causes for whiteflies to attack your plants.
Drought
As previously mentioned, high temperatures and lack of water prevent your plant from attaining a healthy defense against whiteflies.
Dry conditions are naturally more beneficial to insects with piercing and sucking mouthparts. Dehydrated plants become weak and thus incredibly susceptible to the formation of new populations. An additional negative impact is that dry weather reduces the survival of predatory insect larvae such as ladybugs.
Insecticide Overuse
There are no insecticides produced to specifically kill whiteflies. So overusing sprays will destroy a swath of creatures both beneficial and not.
Sure, you can kill off huge amounts of whiteflies, but they are incredibly resilient once they’ve found an attractive home and established themselves. Bees and other pollinators don’t fare well against insecticide, and whiteflies will reappear in abundance.
Nitrogen-Based Fertilizer
Fertilizers rich in nitrogen are essential for the vitality of your garden, increasing the nitrogen levels in plant tissue and promoting health.
Unfortunately, whiteflies are more attracted to plants treated with nitrogen, so experimenting to determine the cause of infestation may lead you to reduce the use of nitrogen-rich fertilizer.
Predator Animals
Birds, spiders, and predatory beetles can control certain pests and do good in your garden, but also can negatively impact your attack on whiteflies. Swifts and swallows are bird species that love to feed on ladybugs and other smaller predators that in turn feed on whiteflies. Finding the right balance is key to maintaining a low whitefly population.
Get Rid of Whiteflies With These Helpful Tips
Whiteflies are certainly a pest that is difficult to avoid, but don’t fear; there are plenty of ways for you to combat the emergence of infestation. In all cases, getting ahead of a young population is key to getting rid of whiteflies. It will only get harder to repel or remove these pesky insects the further they dig in and make themselves at home.
Among inspection, watering, cleaning, and use of both naturally occurring and man-made deterrents, there is a combination of these factors that can best be utilized to keep your garden whitefly-free and healthy!
Try any and all options in order to create the best environment for your plants and worst nightmare for whiteflies.
Good luck and happy gardening!
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