We apologize, but Mr. Smarty Plants needs some time to catch up after receiving an overwhelming amount of mail. Soon, we hope to be taking new inquiries once more. I’m grateful.
ANSWER:
Before, Mr. Smarty Plants responded to a query regarding cholla cactus cochineal bug management (similar to your prickly pears). What Larry and Brigid Larson wrote is as follows: Cochineal feeding can harm the cactus and occasionally result in the host plant’s death. The Cactus Doctor talks about getting rid of cochineal. Their advice is as follows: 1) A hose with a power nozzle attached to the end. 2) It was advised to clean the affected areas with insecticidal soap or unscented dish soap to treat them if the infestation gets out of hand. Neem oil was also mentioned as a possible natural remedy.
In response to another Mr. Smarty Plants query about cochineal bugs on prickly pear cactus, Nan Hampton provided the following response. (As you can see, this is a common query.) It sounds like cochineal bugs are infesting your cactus (Dactylopius sp.). They are cactus-eating small scale insects. They generate fluffy white wax that covers their body as they consume the cactus and shields them from predators as well as the weather (especially drying out). The fluffy wax also acts as a sail or balloon to carry the bugs to a fresh cactus patch in the breeze. The carminic acid that the bugs create aids in shielding them from predators, particularly ants. Indigenous peoples of southwestern North America, Central America, and subtropical South America have been using this bug’s carminic acid for centuries—possibly millennia—to synthesize a vivid red dye that they utilized to create exquisitely colored fabrics. Cochineal bugs were formerly only found in the New World. The cochineal bug spread around the world when European explorers came to a place and saw the stunning red cloth made by the locals. Although they have also been employed to help reduce cactus populations, the need for cochineal bugs decreased when a synthetic red color was created. But recently, there has been a resurgence of interest in cochineal bug cultivation for red dye because it was discovered that synthetic red dyes can have harmful side effects on health. Today, food coloring and cosmetics both employ the bug-derived dye. Because of this, managing cochineal bugs hasn’t really been a top concern, and as a result, I haven’t been able to discover a lot of information on managing them. If you only have a minor infestation, I advise scraping them off (slowly, to avoid the cactus spines) and throwing them away. They might also come off with a water under pressure wash. To ensure that you don’t harm your cactus, test a tiny area first. Then, collect and get rid of any insects that you wash off the cactus.
The University of Arizona Extension also suggests a similar set of remedies in a publication on cactus diseases.
The usage of insecticides was discussed on multiple websites, and Wikipedia included several natural predators: “The population of the bug on its cacti hosts can be lowered by a variety of natural enemies. Insects appear to be the most significant group of predators. Numerous parasitic wasps as well as predatory insects including ladybugs (Coleoptera), different Diptera (like Syrphidae and Chamaemyiidae), lacewings (Neuroptera), and ants (order Hymenoptera) as well as pyralid moths (order Lepidoptera), which kill cacti, have all been identified.”
Here is more information on the intriguing world of the Dactylopius coccus cochineal scale insect and the carmine dye that was highly sought for fabric dyeing in the 15th century.
Is there meant to be fur on my cactus?
Despite being generally robust plants, cactus can experience some problems. Your cactus plant may have white fuzz spots as a result of a bug infestation. Be sure to take quick action to prevent serious harm to the cactus.
On my cactus, how do I get rid of mealybugs?
Mealybugs can be readily removed if you catch them early, before they have a chance to multiply.
Scrape the mealy insect off your cactus by using a q-tip in rubbing alcohol that is 70 percent strength.
To be sure, examine the plant from top to bottom. For a few more days, check the plant daily to make sure no new pests have arrived.
For each mealybug, use a different side of the q-tip because you don’t want to distribute them more than required.
You will need to spray your plant if the mealybugs are more numerous and cannot be removed one by one.
Before you can totally get rid of these pests, you will need to repeat treatment multiple times to destroy them in all stages.
Using a Homemade Dish Soap Spray
Making your own homemade mealybug spray from things you probably already have on hand is another option.
Neem oil, if you can find it, should be added to the combination for a far better success rate.
Your plant will receive a layer of protection from neem oil, making it more difficult for insects to eat through it.
With Blue Dawn dish soap and a 2 percent soap to water ratio, I’ve had the most results.
For instance, my spray bottle holds 650ml (or 20 oz), so I added 13ml (or half an ounce) of dish soap before adding water to cover the remaining space.
Use distilled or bottled water to prevent mealybugs from benefiting from the minerals in your tap water.
You want to make sure you get every area of your cactus since these small creatures can hide in crevices and crannies. Spray this mixture immediately on the surface of your cactus.
If there are still some bugs present, repeat the process again in a few days. To remove any remaining soap, spritz the cactus with distilled water after the bugs have all disappeared but don’t use any soap this time.
Avoid using too much soapy water because dish soap is still a detergent and might harm your houseplant if used excessively.
Use 70% Isopropyl Alcohol
The best method for getting rid of mealybugs on your cactus is typically to kill them using isopropyl alcohol.
Spray every bug and white fuzz spot you notice with 70% isopropyl alcohol (often referred to as rubbing alcohol) with a spray bottle.
Avoid using alcohol that is 90% strength since it will flash off too rapidly and not be as effective.
And if you opt for this strategy, be careful to keep your plant away from hot or direct sunlight to prevent burning. Spray ideally in the morning or at night.
The mealybugs are almost instantly killed by the isopropyl alcohol, which almost dries them up on touch. This will only work if you spray every single bug you see, just as the soap water method.
However, be careful with the alcohol; too much of it can harm the plant.
It might be better to dip a q-tip in the isopropyl alcohol and kill the mealybugs one at a time if you have caught them early and are certain that there are only a few bugs.
Nowadays, it can be challenging to get isopropyl alcohol, so if you can’t, try the dish soap and neem oil method first.
As there are probably other components in hand sanitizer that could be detrimental to your plant, I wouldn’t advise using it to get rid of mealybugs.
Systemic Insecticide Spray
Finally, you can buy systemic pesticide (bonide granules) at your neighborhood garden center or greenhouse to eradicate mealybugs from the inside out. Mealybugs become poisoned by the fluids.
In essence, you’ll water your cactus while using the pesticide, which works more like an antibiotic than a topical application like the other two techniques.
I advise applying a spray (either the soap mixture or rubbing alcohol) together with the systemic pesticide to get rid of mealybugs permanently.
This is because mealybugs may still be present in your soil, making it preferable to attack them from all sides.
Ideally, repot your plant in fresh soil if you can to ensure that no bugs or eggs are still present.
Other Methods That Might Get Rid of Mealybugs
You might try taking the natural approach and introducing other bugs that will devour the mealybugs if you have mealy bugs on your outdoor cacti.
Ladybugs will devour them, and mealybugs and aphids are both consumed by the larvae of the Green Lacewing.
To eliminate bugs, larvae, and other pathogens, some people bake their soil in the oven.
You can sterilize a small amount of soil by putting it on a baking sheet and roasting it in the oven for roughly 45 minutes at 175200 degrees Fahrenheit.
Method #1: Cut Off The Infected Area
To start, use a sterilized knife or pair of clippers to remove any patches of fungus on the cactus plants.
Then, depending on the fungicide you use, treat those healthy areas once every two weeks for six to twelve months.
Follow the directions on the fertilizer container to fertilize your plant as necessary to encourage development and stop further disease outbreaks.
Additionally, make sure that it receives consistent watering throughout this time and try to avoid letting it become completely dry in between waterings since too much moisture may result in black patches in addition to root rot issues!
Method #2: Use Baking Soda and Hydrogen Peroxide
Making a solution of baking soda (sodium bicarbonate) is one of the most used techniques.
Pour two teaspoons into an empty spray bottle along with one quart of warm water.
Whenever you notice any indications or symptoms, such as leaf spot, that fungus on cactus plants has resumed its attack, spray your cactus plants well until they are completely moist, including the undersides and tops of leaves.
For six weeks straight, you should perform this procedure at least twice a week to completely eradicate the fungus on your cactus plants.
Method #3: Make Your Own Fungicide Solution
In an empty spray container, combine one tablespoon of liquid soap, hydrogen peroxide, and baking soda with one gallon of water.
To totally get rid of fungus on cactus plants, spray it abundantly onto your plants every two weeks for at least six months!
Method #4: Spray With White Vinegar Solution
Another choice is to carefully dip the leaves into a solution of one part white vinegar (or apple cider vinegar) to four parts water in an empty plastic bucket or container. Do this until the leaves are completely moistened but not dripping wet.
The fungicide that has remained on the surface should be allowed to dry naturally rather than being rinsed off because doing so will only remove around half of it. It is therefore better to leave it alone.
This remedy must be used within a week if it is homemade. If you purchase it, be sure to keep it in a dry, cold environment.
Method #5: Clean Your Cactus Plant Thoroughly With Soap and Water
The easiest option is to just give your cactus plant a thorough washing every day, or at least every other day, with soap and water, especially after working near them while they are dusty.
Before applying fungicide using method number three above, make sure to clean up any dust since it acts as an insulator to prevent fungi from drying out.
Spray two quarts of lukewarm water with one tablespoon each of liquid soap, hydrogen peroxide, and baking soda to clean all leaves, including the undersides.
Method #6: Use a Fungicide Solution
Fungicides can be used to treat your cactus plant if it develops a fungus infestation.
Fungicides come in a variety of forms, some of which function better than others and serve distinct needs. Be careful to pick the proper one for your situation!
Keep in mind that even if just one or two leaves exhibit symptoms, it is still crucial to spray them down because, if left untreated, this disease will soon spread throughout the entire plant.