If a white coating spreads out on cacti, appearance and vitality are equally impaired. The two most common causes of the problem can be found here. Use our tips for effective natural control.
Lice can be the cause of white coating on cacti
Cause #1: powdery mildew
Powdery, white coating on the green epidermis indicates the fungal infection powdery mildew. As the disease progresses, the infected parts of the plant turn brown and die. How to act correctly now:
- Cut off severely infested parts of the plant and dispose of with household waste
- Treat the cactus with a mix of 1/8 liter of fresh milk and 1 liter of lime-free water
- Spray on the milky water every 2 to 3 days
- Alternatively, dust the affected plant with rock dust
Get help from the animal kingdom for cacti in the greenhouse. Mushroom ladybirds (Psyllobora vigintiduopunctata), sixteen-spotted ladybirds (Halyzia sedecimguttata) and squirrel hoverflies (Myathropa florea) enthusiastically graze on the mushroom lawn.
Cause #2: Mealybugs
If the covering is reminiscent of small, white cotton balls, you are confronted with a pest infestation. These are 1-5 mm small mealybugs and their larvae. The parasites protect themselves with a waxy shell and suck up the plant sap. A greasy, white plaque forms on contact, so the pests are also known as mealybugs. How to deal with the plague:
- Dab individual infested areas with alcohol-soaked cotton swabs
- Sprinkle large areas with alcohol or lemon balm spirit
- Alternatively, fight with a mixture of 1 liter of water and 15 ml each of soft soap (44.90€) and spirit
The use of beneficial insects has also proven effective in combating mealybugs. This applies in particular to locations such as the greenhouse, greenhouse or conservatory. The Australian ladybird (Cryptolaemus montrouzieri) has lice at the top of its menu. The beneficial insects are bred in special farms and can also be purchased there.
tips
If the coating on cacti appears more greyish than white, you are dealing with gray mold (Borytis). This fungal infection often occurs in desert cacti that are placed in a humid location. In the early stages, an immediate change of location to a sunny, air-dry spot can help. Otherwise you cannot avoid disposing of the affected cactus.