Despite all precautions the green gardener undertakes there is always a moment that some pests and diseases become uncontrollable in the succulent garden.
These are in general all related to the unpredictable weather such as flood rains; fluctuating (significant) temperature changes, etc.
Also we have to battle with these, unforeseen, ‘surprises’.
Prevention is always the best and despite good drainage, good weed control , hygiene and other measurements there are those tempting moments when aphid-populations on plants are becoming ‘over-crowded’ and fungi-, bacterial- related diseases threaten to destroy your plants.
There are a few good green alternatives to keep pests and other diseases under control. In our garden we apply them with success.
The first smelly one is the use of khaki bush (Tagetes minuta); a South African native but also in cultivation in other parts of the world. Twice a year applied to the soil just before rainfall it will keep the fungi- and bacterial related diseases (f.e. neck rot) at least under control or even diminish the rest totally. Fill a bucket with this ‘weed’ and poor boiling water over it. Let it rest for a few days and than apply it to the soil in relatively large quantities (better plenty than less plenty). Apply it in late Autumn and the beginning of Spring.
Insects like aphids and scale insects can be kept under control with a garlic (Allium sativum) tea. Crush the garlic. With crushing a natural sulphur compound is released and this compound does the job. 100Grams crushed garlic for every 10 litres of boiling water. Add a spoon of pure butter (this will make the mix nicely and equally flow out over the plant). Mix it thoroughly and let it cool of. Than filter it and mist-spray over the plants. It will keep insects away and a surplus of insects on the plant will try to find another source. One disadvantage: you will have to apply this mix every 3 or 4 days (during ‘high insect traffic periods’) but it is effective; most effective when you can foresee an expansion of the insect population. For example high temperatures after Summer rainfall.
Also effective and sometimes ‘advertised’ as green is a mix of white spirit and soap. Even if the soap is fully bio-degradable it’s not our favorite because the white spirit can be harmful for some sensitive plants (damage of chlorophyll).