It looks like your dracaena is heavily infested with mealybugs. This is a very difficult insect to manage. You should isolate this plant if it is near other indoor plants. Please see the following information from our website,
https://extension.umd.edu/hgic/topics/mealybugs-houseplants

You do mention that you have had this plant for a long time but sometimes it is easier to dispose of the plant and purchase a new one. Battling mealybugs can be frustrating.

Deb

Please read the link we provided for treatment options.  Yes, you can cut off heavily infected stems.  That reduces the load.  

Yes, putting it outside may help somewhat.

 Isolate it from all other houseplants.  Mealybugs will get on any hosueplants.

 If the planter has sentimental value, you can always just replant with a new plant.  

 Ellen

Mealybugs will attack just about any plant. If you put the plants outside place them in the shade. If you put them into too much sunlight the leaves will get sunburnt. Is the Dr. Earth Spray you have labeled for houseplants. If it is it is better to use that than a homemade spray. Homemade sprays can also damage leaves sometimes. The mealybugs may have seemed to have disappeared but there are probably eggs laid on the plant. Their populations can increase quickly. Be vigilant and persistent. You can also use a q-tip barely moistened with alcohol to wipe them away.
Good luck!
Deb

You are welcome.

I think you should quarantine them for at least two more weeks. There are many generations of the bugs on your plants there could be eggs hidden somewhere on the plant that haven't hatched yet. And the fact that you can see even a little bit of evidence of them I  think they need to be kept separated. Keep doing what you have been doing. Mealybugs can appear again quite suddenly.

Deb

I would move the infected plant back outside into the shade and treat it as you did the others. To prevent an infestation, check new plants thoroughly for any signs of mealybugs or other pests isolate new plants for at least a week, be careful when you are moving from plant to plant like when watering or removing leaves. Wipe off tools and the tip of the watering can. The following article may have some additional tips.
https://wimastergardener.org/article/mealybugs/#:~:text=The%20best%20way%20to%20control,week%20or%20so%20if%20possible.

Deb

Unfortunately, this is the insidious nature of mealybugs - they are hard to control once a plant with an infestation is brought into the home. Complicating matters is the fact that some mealybugs can also feed on plant roots - the top growth may appear "clean" after repeated treatments, only to become re-infested days or weeks later when they re-colonize the stems and leaves from below. Vigilance is key and the plants must keep getting treatment any time mealybugs are visible, or new generations will keep being produced by any adults that escape being sprayed by being hidden.

If topical sprays are not working, try systemics if none of the infested plants are being used for food (in case you have infested herbs, citrus, etc.). Systemic insecticides are absorbed into the plant tissues (in this case, through the roots), and while they take longer to start working because of this absorption period, they will last longer and provide more thorough control. Look for a product labeled for houseplants that contains the active ingredient imidacloprid. (This insecticide is not permitted for homeowner use in MD on outdoor plants, but is permitted indoors.) It is applied as granules which should be wet-down after application. It may have a bit of an unappealing odor until it fully dissolves after several waterings. (How long this takes depends on how often the plants need water; don't over-water them just to dissolve it faster, because that will only harm the roots.)

Because this treatment is absorbed at root level, it will hopefully knock-down any hidden soil mealybug populations as well as those tucked into leaf stems and other hidden areas. Check the product label for all instructions including dosing recommendations, as they are typically dependent on the pot diameter size. You may have to extrapolate doses for pot sizes not on the label.

Miri