What are the causes of root rot in orchids and what are the prevention methods?

OrchidsCauses and Prevention Measures of Root Rot

There are quite a few orchid diseases, and root rot is a common category among them. For beginnersgrowing orchids, it is difficult to grow orchids well, and symptoms such as burned tips and collapsed seedlings appear. The reason, in most cases, is root rot. As the saying goes,to grow orchidsfirst grow the roots. Good roots, vigorous leaves, fragrant flowers. Tocultivatea good pot of orchids, you must start by growing the orchid roots well. Only when the root system develops vigorously and its functional capacity is well developed can the absorption and transport of water and nutrients, photosynthesis, respiration and the accumulation of stored energy proceed normally, and only then will growth rate, reproductive capacity and flowering rate increase. Otherwise, if the root system is poor or rots and is lost, the absorption and transport of water and nutrients is blocked, photosynthesis, respiration and other capacities are reduced, and the orchid will gradually decline and die. Orchid root rot is mainly caused by the following two aspects:

(1) The growing medium lacks the function of draining water and allowing air through. Water is the source of all things, andorchidscan only absorb and transport nutrients and carry out normal metabolism when there is water for growth. Orchids are epiphytic plants with aerial roots. During their growth, apart from a small portion of the water they need being supplied by moisture in the air, most of the water must be taken up from the water contained in the growing medium, and the orchid roots must also absorb oxygen from the pores of the medium in the pot for respiration. If the medium in the pot drains poorly and has too high a water content, water will fill the pores of the medium, causing waterlogging. When the pores of the medium are filled with water and lack oxygen, the roots suffocate from lack of oxygen, and over time the function of the root system is gradually lost. At this point, because harmful pathogens invade and multiply, the root system will rot as a result.

(2) The water quality is not clean or the pH value of the water is unsuitable. The water used for orchids must be clean and free of pollution. If unclean water is used, some harmful pathogens or toxins will erode and contaminate the orchid roots, causing serious disease of the root system, stems and leaves, and the roots will blacken and rot and the orchid plant will die. The pH value of the water used for orchids must be between 5.5 and 6.5. If the pH value is below 5, it is on the acidic side, which will restrict the orchid roots' absorption of major elements such as nitrogen, phosphorus and potassium, and the orchid plant will lack major nutrients and its leaves will show yellowing. In an acidic environment, soil-borne pathogens such as root rot pathogens are most suited to grow and multiply, harming the root system and speeding up the rotting and death of the orchid roots; if the pH value is above 8, it is on the alkaline side, and alkaline water and medium will obstruct the absorption of trace elements needed for the growth of the orchid plant. If the orchid roots and plant cannot get the nourishment of trace elements, they will gradually wither and die. In response to the above two problems, some corresponding measures need to be taken during cultivation:

(1) Choose and mix a good orchid growing medium. The orchid growing medium must drain water and allow air through, be moist but not waterlogged, and dry but not parched. There are many special orchid growing media sold on the market now, and they are very suitable, such as Mount Emei soil from Sichuan, expanded clay from Chongzhou, and various special orchid soils from Guangdong, all of which are very good orchid growing media. You can also mix part of leaf mold into these media to supplement insufficient fertility. You can also use local materials, such as weathered soil, crushed brick granules, crushed charcoal granules, crushed oak bark, etc., mixed with an appropriate amount of leaf mold. The effect is also very good: it drains water and allows air through, retains moisture without waterlogging, and also has a certain fertility. But note that the materials used must be non-toxic, sterile, free of pollution and free of parasitic insect eggs, otherwise they will also harm the orchid root system.

(2) The water used to irrigate orchids must be clean. Polluted water and unclean water cannot be used. Many orchid books say that stream water and river water are most suitable for orchid growth, but most orchid growers live in cities and are not professional orchid garden operators, so it is very difficult to meet this requirement. As for watering orchids with tap water, from many years of practice the author has seen that the effect is also very good. If conditions allow, put the tap water in a bucket or basin for a few days to let the chlorine in the water volatilize, which is even better. If spring water or pond water is used to water orchids, attention should be paid to testing the pH value with pH test paper. If the pH value is less than 5, alkaline substances such as lime can be added to adjust it; if the pH value is greater than 6.5, hydrochloric acid, acetic acid, citric acid, etc. can be used to adjust it.

(3) No matter what material the orchid pot is made of, the bottom of the pot must have appropriate holes, and it is even better if there are several holes around the lower part of the pot wall. In short, it must allow air through and drain water. When planting orchids, a layer of crushed brick granules or charcoal granules can be placed in the lower part of the pot to facilitate drainage and air flow. In placing the orchid pots, the air at the bottom and around the walls of the pots should be allowed to circulate. If conditions allow, orchid stands can be used to raise the pots off the ground, which gives an even better effect. To grow good orchids, suitable temperature, humidity, light and other environmental conditions are needed, but creating a good environment for the orchid roots is the most important link. If you cultivate the orchid roots well, you can also cultivate ideal orchids.