Getting Rid Of Spider Mites On Roses
By: Stan V. Griep, American Rose Society Consulting Master Rosarian, Rocky Mountain District
By Stan V. Griep
American Rose Society Consulting Master Rosarian – Rocky Mountain District
Spider mites can be tough customer pests to deal with in the rose bed or garden. One of the reasons that spider mites become a problem in the garden is the use of insecticides that kill their natural predators. One such insecticide is carbaryl (Sevin), which pretty much wipes out all-natural predators of the spider mites, making your rose bush a virtual playground for these annoying pests.
Symptoms of Spider Mites on Roses
Some symptoms that spider mites are at work on your roses would be discoloration or bronzing of the leaves/foliage and scorching of leaves. Left untreated, foliage injury can lead to leaf loss and even the death of the rose plant. When the spider mite population on roses is high, they will produce some webbing on the plants. It will look like a rose with spider webs on it. This webbing provides them and their eggs with some protection from predators.
Controlling Spider Mites on Roses
To control spider mites by chemical means will require what is called a miticide, as few insecticides are effective against spider mites and many can actually make the problem worse. Most miticides will not actually get to the eggs so another application 10 to 14 days after the first application will be required to gain control. Insecticidal soaps work well in controlling spider mites too, just as in the control of the tent caterpillars, but will typically require more than one application.
A key note to make here is that no insecticides or miticides should be applied to rose bushes or other plants during the heat of the day. The cool of the early morning or evening are the best times for application. Another very important rule is to make sure the plants and bushes have been well watered prior to the application of any pesticide. A well-hydrated plant or bush is far less likely to have an adverse reaction to the pesticide.
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Rose Insects & Related Pests
Factsheet | HGIC 2107 | Updated: Nov 12, 2019 | Print | Download (PDF)
With their showy and often fragrant blooms, roses are easily one of the most popular flowering plants grown in South Carolina. Unfortunately, the numerous insects and related pests that attack them can make growing them “interesting”, if not outright challenging. As with any plant, the first priority should be to provide the rose with the cultural conditions that it requires. A vigorously growing rose is much more likely to survive pest damage than a stressed plant. For more information on the cultural requirements of roses, see HGIC 1172, Growing Roses and HGIC 1173, Pruning Roses. For information on diseases of roses, see HGIC 2106, Rose Diseases.
When trying to control insects and related pests on roses, it is essential that the plants be thoroughly inspected on a regular basis. These inspections increase the likelihood that a pest infestation will be detected early, when pest numbers are low and control is easiest. In order to choose the best control method, it is necessary to correctly identify a pest first. Often, more than one control option is available for a pest. Whenever possible, physical control measures should be tried first. If a chemical control is necessary, the least toxic chemical should be used, being sure to apply it when a susceptible stage of the pest is present. When applying a pesticide, thorough coverage is important. Always be sure to read the pesticide label before purchasing. Apply all pesticides according to label instructions, following all precautions.
Where do Spider Mites Come from?
Spider mites are somewhat related to spiders and ticks, but they’re not the same. They are very tiny and difficult to see from bare eyes unless you look carefully. Their species also spin spider-like webs but rather small and dense to protect their eggs and young mites from predators.
Spider mites transfer through eggs, from the surroundings or from the infected plants you buy from the nursery. They survive the winters in the egg stage and thrive in the warm weather. They prefer hot and dry conditions around them and become active in the spring and summers. In a hot climate, their life cycle continues year round.
Mites are the most prevalent pests that indoor plant growers face as indoor conditions are most suitable for them due to normal temperature and dry air. That’s why one of the ways to prevent spider mites is gushing water on leaves of the affected plants.
Resembling a thick worm, rose slugs crawl up plant stems to reach the green foliage. The plant material nourishes their bodies so that they can grow into sawfly wasps. If a large number of rose slugs attacks one particular plant, it will not have enough energy from photosynthesis to stay healthy the plant will die since its photosynthesizing cells are reduced by the slugs' feeding practices. Careful observation is key to keeping your miniature roses healthy. Hand-pick any individual slugs from the plant, but use an insecticide soap to rid the plant of a large slug population.
Caterpillars consume a lot of foliage to gain enough strength for metamorphosis into a butterfly or moth. Your miniature rose plant will have distinct leaf holes from their feeding habits. You can remove them by hand or use an insecticidal spray to keep them away for a longer period of time. The plant will become skeletonized if the caterpillars are allowed to remain on the leaves.
Writing professionally since 2010, Amy Rodriguez cultivates successful cacti, succulents, bulbs, carnivorous plants and orchids at home. With an electronics degree and more than 10 years of experience, she applies her love of gadgets to the gardening world as she continues her education through college classes and gardening activities.
Tell Spider Mites to Bug Off
Spider mites flourish in warm, dry conditions so water plants regularly to safeguard against infestation.
The tiny spider mite can wreak havoc by feeding and sucking the sap out of the leaves of nearly 200 varieties of plants, including fruit trees, ornamentals, grapes, corn and roses.
Photo by: Image courtesy of Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org
Image courtesy of Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org
Although they are less than a millimeter in length, spider mites are among the most formidable garden pests, feeding on nearly 200 varieties of plants, including fruit trees, ornamentals, grapes, corn and roses. Puncturing epidermal cells of leaves with sucking mouthparts to extract sap, the damage they cause is readily evident as leaves become discolored and wither. When an infestation is severe, plants stress can be severe and lead to plant death. Because spider mites, a member of the Acari family, are so tiny, their presence often goes overlooked and damage to trees and crops is already underway. Spider mites reproduce quickly, in some cases, like that of the common two-spotted mite, spider mites can lay as many as twenty eggs a day, with offspring reaching reproductive maturity in less than a week.
Laying their eggs and also feeding on the underside of leaves, many spider mites produce webbing used to protect eggs and feeding colonies from predators and shifting weather conditions. When a spider mite population is high, the silky threads found on leaves are an indisputable indicator of an infestation.
Spider mites have numerous predators, including lady beetles, big-eyed bugs and spiders. In many cases, an extreme infestation of spider mites may be the result of the overuse of chemical pesticides, which can severely reduce the presence of beneficial insects and leave a spider mite population to grow without intervention. When a growing spider mite infestation reflects a dwindling predator presence, discontinuing the use of chemical insecticides may restore balance to a garden space. The return of beneficial insects takes time, however, and this strategy for spider mite management should be considered as a long-term solution.
Spider mites flourish in warm dry conditions. In areas where problems are likely to emerge, making sure plants are watered regularly is an early safeguard against infestation. In circumstances where an infestation has already been established, affected plants may be watered using a hose with a spray nozzle and directing the stream directly at plant leaves can dislodge eggs, feeding adults and wash away supportive webbing.
Inspect plants daily for eggs and mites, giving special attention to the underside of leaves. Prune any leaves that show extreme damage or heavy active infestation. In some cases, it may be necessary to cull entire plants. Any leaves or plants removed as a result of a spider mite occupation should be submerged in soapy water or sealed in an airtight container and removed from the site.
In cases where other management techniques are not sufficient to control an expanding spider mite infestation, chemical intervention should be considered. Many insecticides are ineffective against spider mites and may worsen conditions as beneficial insects lost to treatment. Select miticides specifically for the control of spider mites and follow manufacturer instructions. Although appropriate miticides will eradicate nymphs and adults, eggs will not be affected and multiple applications will be needed to interrupt a cycle of reproduction.