Scale Treatment on Cacti & Succulents

Introduction and Identification of Scale

Close up of Scale on Cacti

Scale is a common pest of cacti and succulents in particular those who are stressed for any number of reasons. Scale can be identified by small, commonly white, black or brown, circles on the flesh of the plant which can be "flaked" off easily and have a speck in the centre usually of a darker color (see scale close up image). Scale insects can over time leave permanent damage to the flesh and also stunt growth. This method will not kill the pests completely and the underlying sources of the infestation should be investigated, some common causes include:- Sun/Heat Stress, Under watering, Over watering, poor soil quality, nearby plants in poor health among many others.

This method should be performed later afternoon in a shaded area with no direct sunlight for the duration where possible. While not covered in this particular guide as yet, i may add it in later, potting the plants into fresh soil and utilizing this time to check the roots for root mealy bugs, scale and fungus gnats is advised.

Equipment

 - Toothbrush
 - Dishsoap
 - Neem Oil (optional but advised)
 - Cup
 - Spraybottle (waterbottle with hole pricked in lid is sufficient)

Goal

The ultimate goal with this technique is to remove all the scale insects from the flesh of the cacti and to hopefully kill them through suffocation in the soap suds/neem oil. Ongoing treatment of the plants infected will be required until the pests stop re-infesting, harsher options are available but this method works well enough.

Technique

1) Quarantine

The first thing you want to do is get all plants with scale away from those which are healthy. Place these onto a table somewhere away from your collection and at an easy working height. If you find any particular cuttings or plants that are particularly sick remove them and discard or mark for ongoing quarantine and more frequent/invasive treatment. As can be seen from the below photos one of the pups planted next to this particular cacti is dying off and seems to be a source for infestation, as such it is removed and destroyed.

2) Brush Down

You want to prepare a mix of dish soap (or neem oil if there is a substantial infestation) and water and mix together well. Using an old toothbrush thoroughly brush the surface of the plant ensuring all scale is removed. Give a final brush with an excess of soapy water and sit aside while wet for later. You may wish to rinse and repeat this step to ensure you get all the scale.

It is advisable to rinse the tooth-brush between brushes to remove any excess scale that you can.

3) Clean Down

After leaving the plants to sit for an hour or so gently wash the surface giving it another quick brush and final rinse. I prefer to use a pressurized sprayer but a plastic bottle with a hole in the lid also works fine. Keep in a shaded area the following day and do a final rinse down and put the plants back out.

4) Ongoing Maintenance

Check the plants every few days over the first fortnight. Just using a brush and water you can quickly clean them off.

After the first two weeks give a full neem oil scrub down to really stamp out the pests. Continue with this for approximately two months or until you manage to nurture the plants back to health ensuring any underlying conditions are fixed.