Rainy and cool weather, continued tofor a long period of time, it is very dangerous for orchids, as it promotes the emergence of such terrible diseases such as black rot. This disease occurs as a result of settlement of plant fungi (for example, Pythium ultimum or Phytophthora cactorum) and affects a wide variety of orchids, but especially susceptible to them is a cattleya (lat.
Black rot if not treated quicklydistributed throughout the plant and as quickly spread from one plant to another, therefore, in the short period of time can destroy the entire collection of orchids.
The fungi that cause black rot of orchids,They can only live in a humid environment. These fungi are composed of so-called zoospores that are capable of independent movement in the water - they swim in it. If such contaminated water is on the list of orchids, the zoospores can penetrate the plant tissue, and it will start the next stage of their life cycle. At this stage, the fungus develops vegetative parts or mycelium consisting of hyphae, threadlike thin tubes, which quickly spread throughout all tissues of the plant. And once this happens, the first visible signs of infection - a small, watery, transparent stains - grow and turn into large brown or black areas.
If the fungus attacks seedlings - and that, as a rule,It occurs at the soil surface - the young plants die due to blackleg. Adult plant disease can strike at any part of it - on the leaves, roots or pseudobulbs, but most often it originates on new leaves growing and progressing down the plant, reaching the roots. Affected leaves may turn yellow around the infected area and the affected places will be soft and when pressed will trickle. However, the most dangerous rot the roots and pseudobulbs reason, because it leads to more rapid destruction of orchids.
Unsterilized pots, contaminated water forirrigation, and water trapped from infected plants, - all common sources of the fungus. To avoid contamination of plants located in the open air, they should be raised to a height of 90-120 cm from the ground. Do not leave the orchid leaves are wet for an extended period. The key point in the prevention of disease is good air circulation in the place where there are orchids that will provide a rapid drying of the plants after watering or rain. Improve air circulation and thus prevent rotting orchids at home to help, such as fans. At the first sign of infection is necessary to isolate all infected plants to avoid further contamination of the entire collection. Finally, to prevent the occurrence of black rot on new shoots in spring, some manufacturers recommend use of fertilizer with a high calcium content.
To stop the spread of black rotOrchid is necessary, first of all, to cut (cut), the affected part of the plant so that at the same time and remove a small amount of healthy tissue, bordering on the infected area. Use only sterile tools (knife, a scalpel, and others.). Next, it is necessary to carefully examine the severed part. Sometimes you can see the brown lesions within the tissue, which from the outside looks healthy. In the case of Sympodial plants such as Cattleya, to stop further spread of the disease, it is necessary to cut out all diseased pseudobulbs. If the plant is severely infected, it is necessary to cut and part of the rhizome, piece by piece, until the healthy tissue. In Monopodial orchids, such as Phalaenopsis and Vanda, it is necessary to remove the infected part of the leaf or, if necessary, the entire sheet. It is necessary to stop the spread of the fungus quickly as possible before it reaches the crown, and when the death of the orchid is already inevitable. Then you put the plant in a well-ventilated area and ensure that the cut is well dried up and healed.
Once infected parts were removedplants to protect the remaining healthy tissue is necessary to apply a fungicide. Cinnamon is an excellent fungicide. You can sprinkle ground cinnamon directly to the affected areas, where the infected parts of the plant have been cut. It is also recommended to mix with cinnamon casein glue-based or vegetable oil> to obtain a thick paste. This paste sufficiently waterproof and can be used to cover the wound. Regardless of the method, the fungicide should protect all exposed (cut) place. It acts as a sealant sealing the wounds, so that new infections will not be able to get into them. Another treatment option is the impregnation of the affected plants with fungicide. For example, to protect the seedlings from the black legs, you can pour water from a fungicide immediately after landing. Two weeks after this it is necessary to repeat the treatment fungicide for disease control purposes.</ P>