Pest identification
What's eating my monstrose apple cactus?
Mealybugs
Signs: White waxy wool packed into the irregular folds and crests of the monstrose stem; colony can be large before noticed
Control: Use a fine paintbrush with isopropyl alcohol to reach every crevice; follow with neem oil spray
Scale insects
Signs: Hard disc-shaped bumps adhered in the grooves of the monstrose surface; sticky residue and sooty mould
Control: Dislodge with a soft toothbrush dipped in soapy water, wipe with alcohol, apply horticultural oil spray
Root mealybugs
Signs: Slow unexplained decline; white powder found coating roots when plant is removed from pot
Control: Bare-root, rinse, soak in neem drench, allow to callous for two days before repotting in fresh gritty mix
Keep monstrose apple cactus pest-free
Healthy plants resist pests best. Get the basics right:
Monstrose Apple Cactus pests — FAQ
What is eating my monstrose apple cactus?
Cereus repandus 'Monstrosus' has an irregular, lumpy surface with many crevices where mealybugs and scale insects shelter and evade detection. Its columnar growth means pests on the lower stem are easily overlooked. Root mealybugs can establish in larger pots. Inspect every fold and crevice monthly and treat at first sighting.
How do I get rid of mealybugs on monstrose apple cactus?
White waxy wool packed into the irregular folds and crests of the monstrose stem; colony can be large before noticed Use a fine paintbrush with isopropyl alcohol to reach every crevice; follow with neem oil spray
How do I get rid of scale insects on monstrose apple cactus?
Hard disc-shaped bumps adhered in the grooves of the monstrose surface; sticky residue and sooty mould Dislodge with a soft toothbrush dipped in soapy water, wipe with alcohol, apply horticultural oil spray
How do I get rid of root mealybugs on monstrose apple cactus?
Slow unexplained decline; white powder found coating roots when plant is removed from pot Bare-root, rinse, soak in neem drench, allow to callous for two days before repotting in fresh gritty mix