Table of contents:
- Infectious diseases
- "Cosmetic" defects
- Over-watering cacti (bay)
- Mechanical damage
- Lack of growth in cacti (stagnation)
According to the materials of the forum for 2005-2008, after the gulf of Gruzon's echinocactus, the most common cause of cactus disease is fungal infection. These diseases are slow and unnoticeable. Unfortunately, when the fungus can be identified, there is little to help the cactus. The spread of a fungal infection is facilitated, as a rule, by mechanical damage and high air humidity in combination with low temperatures.
You can get acquainted with the most common causative agents of fungal diseases in the article "Plant Diseases". Here we give photographs and descriptions of fungi on cacti that forum users encountered in 2005-2008.
1. Cactus with spots
The spots appeared in the spring, presumably a fungal infection, anthracnose (brown spot).
Recommendations (Natali): cut out the affected areas, dust with sulfur, and treat the cactus (entirely) with a foundation. Brown spot is contagious.
In addition, it is quite typical for cacti when the fungus occurs
simultaneously with the mite, therefore wet treatment (spraying and watering) with insecticides and acaricides causes the development of the fungus, and in this case dry treatment is recommended (dusting the cactus and soil).
In general, fungal infections appear when the cactus is in adverse conditions. With a lack of light, high humidity and excessive watering.
Black dry spots around areoles, dropping of spines in these areoles. Presumably black rot, which could appear for the following reasons: mechanical damage to the areoles (for example, during transplantation or transportation); contaminated soil; waterlogging combined with a lack of light.
Recommendations (Anyuta): cut to healthy tissue, treat wounds with brilliant green, fungicides.
The cactus was bought already with yellowness, most likely with a fungal or bacterial infection, but it lived for almost four years before other symptoms appeared: lethargy, drying of the papillae. Unfortunately, saving the cactus was already useless.
Was struck by a root worm, the roots dried up, after cutting the stem, it turned out to be orange inside.
Serbin: This is a putrid infection. Also, it can be a virus when the plant slowly loses its green color and gradually dries out from below. Treatment is useless.
In second place are the so-called "cosmetic" defects: first of all, age-related cork formation, then cracks on the body of cacti, various spots (not of infectious origin).
1. Age-related corking
It begins to manifest itself at different ages, depending on the type of cactus and on the correct content. With proper care, corking does indeed occur in an adult cactus (remember that the growing age for different cacti is very different).
In case of minor violations of the regime, suberization begins earlier, the main reason for it is water with cold air. It is impossible to fix the corking, you can only re-root the top and grow the specimen again.
But do not confuse corking (hard cactus tissue) with stem rot, when the surface also becomes light brown, but soft, squeezes under the finger.
A brown crust at the base of the stem can also form when watered with hard water. And also if the cactus is planted in alkaline soil.
2. Corking a cactus from ticks
Sufficiently fast and extensive corking of prickly pear. Opinions were expressed about the defeat of the tick and about the rapid corking due to improper care, but they did not come to a consensus, and the hostess did not apply any more. But there are cases when the cactus trunk was actually covered with a strong crust after being hit by ticks - the wounded epidermis was scarred.
3. Cracks on the body of cacti
They appear primarily due to excessively oily soil containing an excess of trace elements, overfeeding with fertilizers, overflow. If cracks appear, it is better to make sure that fungus does not start on a fresh crack. This defect cannot be fixed.
4. Spots on the coryphant
Colleague: most likely, this is a feature of coryphants, in which juice is released from the areoles and leaves such marks on the body.
Over-watering cacti (bay)
For cacti, excessive watering at any temperature can be a destructive and irreversible process. As a result of excess moisture and lack of oxygen in the soil, putrefactive infections begin to multiply very quickly.
Oddly enough, in addition to the grubs, only one cactus was flooded in three years. The bay is a result of warm wintering and frequent watering. It must be understood that at high temperatures in winter, the cactus will not sleep normally, so it can dry out in a few months without watering.
Therefore, it must be watered very carefully: either check the soil, or water it only after wrinkling. Another mistake - watering a little, the cactus still won't get water, but the root collar will suffer. It will also suffer in the case when the earthen lump is too dense, stuck together and the water stagnates on the surface for a long time.
On the recommendation of Pola, the cactus was re-rooted: first, the roots were cut. But this would not give anything - it is necessary to cut off the entire lower part of the cactus trunk, to healthy tissues.
Here you see two cuts: the first is wrong - there are traces of rot on the cut. The second photo shows that the cut is clean!
After 9 days of drying, k-berd put it on rooting over water. The roots appeared after 3 months, but the moisture from the water in the glass turned out to be critical, I had to dry it again and root it on dry soil.
To the credit of the members of the forum, in three years only two cacti fell on the basis of the topic.
Fall of astrophytum, break of the root collar. Alexander put it on rooting, first dried it for about two weeks, then put it over a glass. A week later, roots appeared.
Lack of growth in cacti (stagnation)
A fairly large number of cacti members of the Masch forum have not grown in the literal sense of the word for several years: not a single new areola, no growth.
Mineral substrate: coniferous grain + sand + brick, upper and lower drainage.
Watering: as with all cacti in the summer - as it dries, in the winter - without watering.
Fertilizers: fertilized for the first year - no results, then did not feed - also no results. Transfer: twice in the spring, examined the roots.
Lighting and location: in summer - outdoors (southwest), in winter - on a windowsill at a temperature of 11 degrees and additional lighting. There are no pests.
Natali: Many cactus species grow normally at an acidity of 4.5 to 6, some with a reaction close to neutral (6.5-7). Soils, which are predominantly coniferous, can be too acidic (pH <4.5) and have unfavorable physical properties. Due to the lack of foundations, organic matter in these soils is not fixed, the soils are depleted in nutrients. Although this land is initially just as low in nitrogen. And although the need for this element in cacti is not as great as in other plants, a lack of nitrogen leads to stunted growth.