There are three main nightmares that these weird and wacky plants can succumb to and they are insect pests, diseases such as fungal, viral and bacterial, and environmental such as growing conditions, I won’t be listing all the different types of bugs etc or all of the fungal and bacterial diseases as there is plenty on this on the internet and it is a very large topic, I just want to include what I do to prevent and treat these pests and diseases in general.
Thankfully Cacti and succulents are not as prone to pests as most other plants are because their thick skins and spines act as a deterrent for many bugs, However if you have been growing cacti and succulents for any length of time you have to be a very lucky person indeed to have never encountered any bugs on your plants, the most common being Mealy bugs and Spider mites which seem to be a magnet for certain types of cacti and succulents, followed by Aphids and scale insects. Many different growers have their own ways of dealing with these pests but I am going to include what I do to most importantly to prevent these bugs as much as possible, as with everything in life prevention is always better than cure.
One of the biggest dilemmas I face when it comes to dealing with pests on my plants is that because I am a Vegan, and for these of you who don’t know what a Vegan is, it is somebody who does not consume any animal products, or wear any animal products including clothes, cosmetics and toiletries that have not been tested on animals as well as avoiding harming other living beings including insects as much as it is physically possible. I always say in my videos that I always like to live with nature rather than against it, and would often spend hours picking off slugs from the bottom of the pots of my plants and putting them back in the garden again a long distance away, I spray my cacti that are prone to Spider mites with rain water regularly which helps to prevent them as much as possible, I will use cinnamon oil on cotton wool balls all around my home and greenhouse to deter Ants and other bugs away rather than harm them, and as for Spiders haha! I love them and just live with them they are part of our home and are the good guys when it comes to our plants.
Check out this video below I made on How to prevent Ants by using cinnamon oil:
Because of this I realise how important it is to prevent rather than treat and thank goodness, other than the odd plant, I very rarely get bugs on my plants these days, I water all of them 4 times a year with natural Neem oil which acts as a natural systemic insecticide and helps to prevent many soil pests such as root mealies and sciarid flies, but if I have a plant that does succumb to bugs such as spider mites, scale insects or Mealies, then I know that if I didn’t treat them they would quite easily wipe out my collection of 2,000 + plants if left untreated, so I do the most humane thing I know of to get rid of them and that is by picking them off, and wiping them off with soapy water, if this does not do the job then I will spray them with a natural systemic insecticide made from Neem oil and mixed with a natural soap such as Pink Sun, and that is rather than resorting to dangerous chemical sprays, this is far more environmentally friendly and does not harm beneficial insects like Spiders and Ladybugs and Bees, as well as being safe for humans too, many growers with large plant populations have great success with biological methods of pest control such as introducing predatory insects that feed off the harmful insects, its what happens in nature naturally, but I have no experience of using this method myself, but something I would be very interested in trying in the future.
When prevention does not work then I like to use isopropyl alcohol commonly called rubbing alcohol, this does kill pests on contact, but sometimes there is no other choice when prevention does not work. Isopropyl alcohol is a far more humane way to kill insect pests on contact as it kills them direct, it is also safe to use and also great to use around the home for cleaning.
I would only ever recommend using chemical sprays ONLY if every other method has been used to control pests with no avail.
Here is a video below that I have made for my You Tube channel on How to remove scale insect from Cactus plants using Isopropyl alcohol / rubbing alcohol :
Here is a video I have made for my You Tube channel on How to remove mealybug from very spiny cactus plants using Isopropyl alcohol /rubbing alcohol :
Here is a video below that I have made for my You Tube channel on How to clean Mealybug from Hylocereus dragonfruit cactus with isopropyl alcohol /rubbing alcohol :
Diseases and disorders
This is such a vast subject and there are many different diseases and disorders of cacti and succulents and much advice on the internet, so here I am going to start off for now by just covering the most common types of diseases or disorders that are commonly encountered in our collections, and will be extending more information on this as the weeks go on.
Mold on Cactus and Succulents
Mold can often be a concern on cacti and succulents as it can sometimes come from Mealybug as they secrete a honey like deposit and sticky black mold can form, mold can also form if plants are grown in too high humidity and cold temperatures. Mold can be cleaned off with a stiff brush and soapy water.
Here is a video below that I have made for my You Tube channel on How to clean mold off cactus plants :
This is often happens because the soil in the pot that the plant is grown is has stayed damp for too long allowing fungi and bacteria to attack the root system, also if a plant has been recently repotted and it is watered too soon after repotting this can cause the plant to rot as the root have not had chance to heal from the re potting. One of the biggest causes of root rot is watering when the plants are dormant, Desert types of Cacti and many succulents like to be kept totally dry over their rest period from late October to early March and watering them during their dormancy is a sure way to encourage root rot. Bad drainage can also lead to root rot, succulent plants like to have a well drained potting mix. If you have a plant that is rotting at the base, it may be saved it you treat it as an emergency cutting by cutting away all traces of rot with a clean sterilised knife and letting the cutting fully callus over before potting back up again. Below I have made some videos for my You Tube channel Desert Plants of Avalon on how to save a rotting cactus.
Suphur powder or Cinnamon powder can be used on the cut parts to help prevent mold forming while the cut areas is callusing over.
Check out this video below that I made for my You Tube channel on Help my cactus is rotting what can I do?
Here is a video below that I made for my You Tube channel on How to save a cactus from rot and take cuttings :
Here is a video below that I have made for my You Tube channel on How to save a cactus from rot :
Here is a video I have made for my You Tube channel on How to save a cactus plant that is rotting from the top :
This often appears as brown corky scabbing on the epidermis of the plant, and is caused from too low of a temperature for the plant, black spots or scabs will often appear on cacti and succulents, and although they may not be life threatening they can be unsightly, plants kept for long periods in too low of a temperature are more likely to succumb to rots, so its important to move any plants showing signs of cold damage to a warmer spot.
Here is a video below that I have made for my You Tube channel on what Cold damage looks like on a cactus:
Check out this other video I have made for my You Tube channel on severe cold damage on cactus :
Sun and heat damage:
Sun and heat damage often happens when plants are growing behind glass and there is not sufficient ventilation, or plants have been exposed to bright sunshine after being for a period in a dull spot, moving plants outside for the Spring and Summer after overwintering then in a duller spot can often cause this to happen. Pale white sunken patches often appear on stems and the plants can sometimes look bleached where the chlorophyll has been damaged. Unfortunately the damage can’t be corrected but will grow out over time. If you have overwintered your plants in a shadier spot, then when it comes to moving plants back out into the garden in the Spring also acclimatize them slowly, to avoid scorch on the stems as much as possible
I am sure nearly everyone has seen this on a cactus from time to time although hopefully not on any of ours, you often see these strangely shaped and stretched out looking cacti on the bottom shelf at garden centres. Etiolation is caused from lack of light which causes the stem to stretch out to try to receive as much light as possible making the plant look very strange and unnatural looking. There is no cure for this and the only remedy you can do is to cut off the spindly parts and move the plant into a sunnier position acclimatizing the plant slowly to its new bright spot, over time it should send out new shoots from where it was cut and may end up looking very unique and different from its original pre etiolated appearance.
Chlorosis is a yellowing of the plant and is a condition where the plant is not able to synthesise chlorophyll because it is lacking the nutrients in the soil to make it, and with cacti and succulents this is commonly caused by exhaustion of the soil nutrients, if a plant has been left for many years and is in desperate need of fresh soil, sometimes a re pot into fresh soil is all the plant needs to recover again, also the same PH of the soil over time can often become either too alkaline or too acidic and a change into fresh soil and switching from tap water to rain water is often all it needs, but sometimes it can commonly be caused by soil pests in the soil that are attacking the roots and stopping the plant from being able to absorb nutrients. Whenever a plant looks yellow and it is not caused from bright sunshine or lack of water, always take it out of its pot and inspect the roots, in the past I have always found that if I have a plant that is looking yellow and sickly, it is nearly always down to the plant needing fresh soil either caused by lack of nutrients or the PH of the soil becoming either too acidic or too alkaline over time, and or soil pests like root mealy bugs on the roots.