scale - Ask Extension
I have been fighting scale on my household plants for years. I use Neem and dish soap but can never get rid of it. I have been told there is a systemi...
Knowledgebase
scale #866700
Asked May 01, 2024, 8:16 PM EDT
I have been fighting scale on my household plants for years. I use Neem and dish soap but can never get rid of it. I have been told there is a systemic plant pest killer but I cannot find anything online. None of the affected plants are being consumed. I would not put poison on edible plants. I have beautiful clivia, crinum lily, begonias and many amiryllus and some orchis. Please help! How can I defeat this terrible pest?
Windsor County Vermont
Expert Response
Hi, Jan. Thanks for reaching out to the Extension Master Gardener Helpline, and thanks for your patience. I'm assuming that you have already identified your scale as "brown soft scale", which is common on many house plants. However, if you're not sure if it's scale or mealybugs (a relative of scale) this link has good photos and descriptions: https://extension.umn.edu/product-and-houseplant-pests/insects-indoor-plants#mealybugs-1581111
One of our house plant experts tells me that these pests tend to return under certain conditions. She suggests that overwatering could be contributing to their return. Be sure soil is dry before watering, by using a water meter probe or by sticking a finger into the pot an inch or two.
She also mentions, as do other sources, that when using horticultural soaps and/or oils, multiple applications are necessary to be effective.
This link from Colorado State, https://extension.colostate.edu/topic-areas/insects/brown-soft-scale-a-common-insect-pest-of-indoor-plants-5-599/, gives detailed information about scale, including how and when (what part of the scale life cycle) to use insecticidal soap, horticultural oil, and soil-applied systemic insecticide. If you do opt for the recommended systemic insecticide, you will need to check that it is approved for use in Vermont, and you will need to follow instructions on the product carefully.
Finally, if you have a heavy infestation, the standard advice is to isolate the plant, to protect other plants. And though I know you will hate the thought, another option for heavy infestation is to discard the infested plant and replace it with a new one.
I hope that this will be useful for you in your battle against scale. Let me know if you have further questions.
One of our house plant experts tells me that these pests tend to return under certain conditions. She suggests that overwatering could be contributing to their return. Be sure soil is dry before watering, by using a water meter probe or by sticking a finger into the pot an inch or two.
She also mentions, as do other sources, that when using horticultural soaps and/or oils, multiple applications are necessary to be effective.
This link from Colorado State, https://extension.colostate.edu/topic-areas/insects/brown-soft-scale-a-common-insect-pest-of-indoor-plants-5-599/, gives detailed information about scale, including how and when (what part of the scale life cycle) to use insecticidal soap, horticultural oil, and soil-applied systemic insecticide. If you do opt for the recommended systemic insecticide, you will need to check that it is approved for use in Vermont, and you will need to follow instructions on the product carefully.
Finally, if you have a heavy infestation, the standard advice is to isolate the plant, to protect other plants. And though I know you will hate the thought, another option for heavy infestation is to discard the infested plant and replace it with a new one.
I hope that this will be useful for you in your battle against scale. Let me know if you have further questions.
