Cochineal Eradication / Mealybug Scale (Dactylopius coccus)
Cochineal Scale usually appears on Prickly pears and Chollas, but can attack other cacti. It looks like white sticky mounds-- or tissue paper that has dried on the plants. Inside are cochineal bugs -- if crushed, a purple die exudes. The bugs can cause severe damage and death to the plant if left unattended.
To kill, first wash the scale off using a garden hose with fresh water. Then mix a combination of insecticide, dormant oil spray and dish soap to finish them off. If you don't want to use a pesticide, the soap and oil will kill the scan, but more treatments may be necessary.
Use a hose end sprayer (for large infestations) or a hand carried pump sprayer. Apply a combination of insecticide, dormant oil spray and/or insecticidal soap. Either triazide or Malathion is effective in killing the scale, especially when mixed with soap, Neem Oil or Volck dormant oil spray
Follow the directions on the label. Be careful not to burn up the plants by spraying oils on hot, sunny days. Dormant oils are best used during cool, winter months. Use cautiously during warm weather. Cacti have tough skins, but can be cooked with too much oil. If the weather is too hot for dormant oil spray, use pesticide mixed with dish soap to keep the infestation under control until cooler weather.
If the Cochineal Scale is still alive after 14 - 30 days, spray again. Several treatments may be necessary to eliminate the infestation.
My favorite mix is a stout dose of Malathion mixed with a stout dose of Volck dormant oil spray. This can be effective with just one treatment.
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