A range of fungal and bacterial diseases affect succulent plants, some of which can collapse and die very rapidly, once the disease has taken a hold. The world abounds with fungal spores, which are opportunists, waiting for the correct conditions for germination. Generally, fungi do not affect cactus and succulent plant collections because of the relatively dry conditions used by most growers. Damp conditions are a universal requirement for activation of fungal spores, and many of the problems with fungal infection of succulent plants arise from failure of excessive watering or condensation to evaporate, because of unexpected or seasonal cold weather. Damage from insect pests, which penetrate the plant’s epidermis to feed on sap, may provide a route for entry of fungi into the nutrient-rich inner tissues. Hence, unexpected collapse of a plant is often the final symptom of a mealy bug infestation which has gone unnoticed. On the other hand, some fungi provide their own mechanisms for penetrating the epidermis.
PHYTOPHTORA OMNIVORA produces root and stem rot that spreads rapidly. After the desease identification, we can try to save some parts. Unhealthy tissue should be removed together with healthy surrounding tissue using a clean knife, sterilised with methylated spirits. Plant should be put than on dry place and replanted after appropriate time period (5 to 30 days, due to plant size and aero-conditions. Water it with PREVIKUR after (read producer manual first and text that fallows below).
PREVIKUR (Benlate, Nimrod T) is especially effective against many other fungi, just like: FUSARIUM, PYTHIUM and RHIZOTONIA that often attack seedlings in small pots.
For preventive maintenance, use 2,5ml per 1l solution of fungicid. For cure, there should be two watering in 4 days. The prevention is best affected after replanting, esspecialy with young seedlings. We can use other good fungicids like CINEB 30g per 10l, BENOMIL 4-6g per 10l water (and many other brands in different countries). Some of them (powders) can be mixed with substrate for older plants, but for young plants that is not recommended.
Beside mentioned deseases, cacti can also suffer from BOTRYTIS CINEREA. Simptoms are grey coverings consisted of many conidums. When touched, conidums transform themselves into powder and propagate quickly. Germinating of fungus spores can be prevently stopped by TELDOROM, SAPROLOM, RONILAN-FL or SUMILEX 50–FL (solutions can be read on producer manuals).
Author: Verica Jovanović, plant protection engineer