If you find ants on your dying plants, the ants are usually not the problem, and instead are often indicative of another issue.
If you go on a picnic you can bet that if there is food, there will be ants. In the case of plants, the ants are not attached to the plant, but instead to a sugar-rich liquid called honey dew. Honey dew is a sugary excretion left behind from piercing or sucking insects like aphids or scale. When honey dew is present, then the ants come calling.
After a while a black mold called sooty mold will grow on the honey dew. Although the sooty mold will not kill your plants, it can block the sunlight and inhibit the photosynthetic process.
Working backwards, if you have ants then you probably have honey dew and you will see this black sooty mold. If you have honey dew, then you have aphids or scale attacking your plants, and it’s the aphids or scale that you need to control, not the ants. There are several controls available ranging from a mild soap and water or contact sprays to longer lasting systemic insecticides.
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