Scale insect orchid pests are popular pests among orchid plants in northern climates. From the brown scale to the Boisduval scale, there are over 27 species of scale insects associated with orchids. Scale insect pests, alongside spider mites, aphids, caterpillars, and weevils can infect your orchid and damage the tissue.
If you’re struggling to deal with getting rid of these annoying insects on your orchid, this guide by our cultivation experts will tell you how.
- How Do Orchid Plants Get Infested With Scale Insects?
- How to Free From Scale Insects on Orchids?
How Do Orchid Plants Get Infested With Scale Insects?
Orchid plants get infested with scale insects by being crowded or colonized by the pest, or it can also come when you purchase it, and the plant is infested already. Lastly, when there is a low humidity level in the environment, they would be attracted.
– Being Crowded or Colonization
Colonization usually occurs in orchids grown outdoors. This is when windblown crawlers make their way to plants and infest the parts. Crawlers are mobile nymphs hatched from eggs laid under a matured female scale.
When crawlers hatch, they find an ideal place to settle to feed; this way, they would start feeding on the orchid. The females form a yellowish protective scale afterward, which thickens and darkens as they grow. The male Boisduval then creates an armored scale, and as they come and infest, they will colonize and increase in number.
– Purchasing an Infested Plant
This is the commonest way of orchids getting infected by scale insects. When an infested plant is purchased, it eventually affects other healthy orchids around it. The scale is easily transmitted from plant to plant. The spread is faster if the area is slightly overcrowded, and you wouldn’t see it as much as they are tiny, so they would be infested even before you bought.
– Low Humid Environment
Because you’re growing your orchid indoors or greenhouse doesn’t mean it can’t get infected. Crawlers can float on weak air currents from heater fans. This can lead to infestation when they settle on your plants, and they would feel welcome to come and increase.
The adult brown scale and boisduval usually have a short cycle. However, they can reproduce offspring many times a year. It typically takes a month for the scale cycle to be completed.
The adult brown scale is characterized by its dark brown crucial shells, while a mature female Boisduval scale is lighter and more rounded. The male Boisduval has a cottony appearance, which is often mistaken for mealybugs. The insects appear on leaves, pseudobulbs, and even in roots.
Scale differs in size, ranging between one and five millimeters, so you should know that the size increases as they move from one growth stage to the next. However, they are only possible to see with magnifiers. They move extremely slowly, making it even more complicated to spot them.
How to Free From Scale Insects on Orchids?
To free from scale insects on orchids, you can start by pruning, or using insecticides; you can also try to use warm water or rubbing alcohol to free from them. You may also repot the plant, apply some horticultural soap, neem oil, regular soap solution, or place beneficial insects.
Removing the Boisduval scale on orchids can take some serious effort, and that’s because the control methods differ for each insect and generation. For example, control methods, such as chemicals, are effective against crawlers of light infestations. When their hardened shell mature or they become adults, it becomes more complicated to kill them with chemicals.
While the management method can be tricky, persistence is the key to eliminating these insects. The least toxic methods are usually more laborious. On the other hand, chemical methods, such as insecticides, are toxic and costly but less strenuous.
Pruning infected branches is typically the easiest way to control infestation. However, you shouldn’t prune if the infestation has spread to other parts of the plant. In that case, it’s best to burn it, so make sure to catch and get rid of them.
To prune, identify the infected or diseased part. Position the sterilized tool at an obtuse angle above a node, a small protuberance on the stem that stimulates new growth, and make a clean cut, for this you must take the opportunity to remove any unproductive stem to aid growth. However, after pruning, rub cinnamon powder on the cut ends to prevent the onset of any infections or diseases, and now, you should not apply rubbing alcohol.
Insecticides are the most effective for heavy-scale infestations. Sometimes, the plant’s costs and the owner’s affection for the orchid may force him to avoid using insecticides. However, home remedies or non-insecticidal treatments may not be powerful enough to remove the heavy infestation.
Some insecticides are designated for orchids, but several common and inexpensive options are now available for use. Some effective options are Orthene and Diazinon. Other chemicals include Malathion and Carbaryl. Always read the instructions on the label before use.
Orchids are sensitive to chemicals; some may not react well to certain formulations, so advanced testing is recommended in this case. Never use a liquid insecticide in direct sunlight. Always shade the plants after application until the solution dries to prevent burns.
When using chemicals, ensure you protect yourself adequately. Most of these chemicals are toxic, even in diluted forms. Wear overalls and respirators during application. We advise that you check the insecticide before applying it to your orchid. Never use these chemicals for ornamental plants.
– Use Warm Water
Warm water is a non-insecticidal treatment method. It may not be as potent as the chemical methods, but it can control infestation. Carefully, you should wash the plant in warm water with mild soap and separate it from other orchids for two weeks. Wash again if you can still see the scale on it, but never use ammonia-grated soap, as it will kill the plant, so be mindful of it.
– Apply Rubbing Alcohol
Rubbing alcohol is a prominent home remedy due to its antiseptic and anti-microbial properties. Also known as isopropyl, it is a disinfectant for cleaning surfaces and minor cuts and dissolving sticky residues, but you should also be careful not to use too much of it.
You can apply rubbing alcohol on the orchid leaves with a soft toothbrush to remove the scale. Repeat this treatment twice to eradicate the insects on your orchid. Alternatively, you can spray alcohol with a pump sprayer.
Note that rubbing alcohol isn’t effective in removing eggs from beneath the scale coverings. Therefore, you have to physically remove the scales by hand. Also, rubbing alcohol differs from ethanol and methanol. Ethanol and methanol will penetrate the plant tissue and damage it.
Rubbing alcohol tends to evaporate rapidly when air movement increases, cooling the plant tissues and forming localized dead mesophyll cells. On breezy days, wipe residual alcohol with a tissue to avoid evaporation.
During a heavy infestation, the scale may affect the roots and rhizomes, and for this, you should remember that the potting medium will then harbor crawlers. This is why, you should consider replacing the medium with a fresh one. When repotting, ensure the root is healthy and clean. Spraying the roots with growth hormone will help foster growth.
– Horticultural Oil
This is a petroleum-based oil that can eliminate scale and other nutrient-sucking insects. Some exist as vegetable oils, too, such as soybean oil. Horticultural oil is usually diluted to make it convenient to spray because this is what the pests hate, and they would be vulnerable in this case.
This oil is best sprayed in late spring before the leaves unroll. Spray using a hose-end sprayer with about two ounces of oil per gallon of water. The solution will suffocate the nymphs before they form a shell. You must treat the entire plant and not just the affected part. This is because the insect may be present on the leaves undersides and the plant’s base.
For this, if you do get to the action in a fast way, you should know that orchids can survive scale. They can also die, but that’s rare unless the infestation is severe. You can eliminate the scale on your orchid with chemical control methods, such as insecticides.
– Neem Oil
You can add neem oil or horticultural oil to the solution for more effectiveness. However, you must be careful when applying this solution, as excessive amounts may damage your plant, especially the buds, and flowers.
It contains azadirachtin, a powerful ingredient that offers adequate protection against scale and other insects. This solution is safer for humans and pets than insecticides. One application doesn’t provide absolute control, so apply it frequently. This will put the pests and insects at bay or below a manageable level.
Oil solution stifles insects, so cover all your plants with it. Mixing it with water and a plant-safe detergent will enhance effectiveness. It will enable spreading and sticking. However, never spray these solutions on days above 85 degrees Fahrenheit, so be careful of this notion, because it can leave prolonged damage instead of fixing it.
This oil doesn’t mix well with water, so you’ll want to add dish detergent instead of water. A general guide for this emulsifier is two teaspoons to two tablespoons of oil and a gallon of water. Use a garden sprayer for the application. This oil is an organic pesticide and is not harmful to honey bees.
Insecticidal soap is another alternative control method. It eliminates scale at the larval stage. However, it’s less effective once the scale has developed a shell. To apply, use a spray bottle. Spray on your plant until the leaves start dripping.
For this, you must remember that the rule of thumb is to mix one ounce of some soap with a gallon of water; as you see, the amount of soap must be very little. However, follow the instructions on the package for maximum effectiveness, and this way, you wouldn’t lose the balance.
There needs to be more than one application, and that is because the chemical elements in this soap are not effective for long. Therefore, you’ll need several applications to apprehend all the larvae. Typically, these soapy solutions won’t leave any harmful environmental residue.
While soapy solutions are effective, they may still damage plants, particularly when mixed with hard water. This is so for plants with tender tissues so that these solutions can also be allergic to some users. Never apply this solution to plants that aren’t hydrated, because this way you risk damaging them. Additionally, never use it in direct sun or environments above 85 degrees Fahrenheit.
– Insect-growth Regulators
Growth regulators like Enstar II are insect hormones that inhibit scale development. Information about their use on orchids is still scanty, as most people who go to an orchid society would go ahead and do so to deems them safe for plants. Different users have expressed satisfaction with the results of these growth regulators.
An alternative to the Enstar II is Azadirachtin, it is derived from the neem tree. Like Enstar II, it interrupts the growth of chitin, a fundamental element in insects’ exoskeletons. This inhibition causes their death. It’s been approved for use on ornamental plants and greenhouse applications.
– Synthetic Chemical Pesticides
These pesticides are similar to growth inhibitors. Synthetic pesticides contain acetamiprid and thiamethoxam compounds. They are usually used as the last resort where other methods have failed. Note that they are harmful to honey bees and insect pollinators.
– Beneficial Insects
Beneficial insects can be a crucial and effective control method, and it involves introducing some insects to act as natural predators for the scale. These insects will feed on the scale and other pests. An example of a beneficial insect is the lady beetle. You can purchase beneficial insects in stores.
Note that using different control methods is recommended. Pests become resistant to these methods over time when used repeatedly. Therefore, use a different chemical method up to four times sequentially. For instance, if rubbing alcohol was used for the previous treatment, switch to insecticide or oil solutions.
Scale insect orchid pests are deadly and could wipe out your orchid garden; however, the control methods above can minimize the risk of these extreme infestations. Let’s briefly talk about these control methods:
- Avoid using an insecticide not designated for ornamental plants. Additionally, use at most the recommended concentration. Too little or too great a concentration will negatively affect your plant.
- Using one control method can increase the risk of a treatment-resistant scale population. Therefore, using different chemical control methods is the most effective.
- Monitoring the scale’s life cycle is essential to controlling the crawler’s population. It will help minimize the number of sprays and maintenance costs.
- Handpicking pests is recommended. It will help minimize chemical sprays. You can use this method alongside chemical control methods to optimize effectiveness.
With this information, you understand how to deal with scale and other pests on your plant.
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