Before potting, it is best to disinfect the growing medium first; this step cannot be skipped.

At the end of 2002, I went with fellow orchid growers to an orchid-producing area in Hubei. Out of more than 3,000 wild-collectedCymbidium goeringiiplants, we selected several dozen that we thought were better and brought them back for planting (the flower buds were relatively round, the leaf shapes had distinctive features, and all had a clear fragrance). Because it was winter, the overwintering orchid shed had limited space (the environment was semi-underground, with plastic film, straw curtains added at night and opened during the day; one side of the film was opened a crack for ventilation). In addition, I was busy with work, and to save trouble, I simply found two plastic basins used for selling pastries and temporarily potted them to get through the winter first. The growing medium was a small amount of peat soil, weathered rock, decomposed pine needles, and used fine sawdust from mushroom cultivation. Two months later, several orchids showed dehydration. When I checked the orchid roots, there was nothing abnormal (at that time the maximum daytime temperature in the shed was about 10°C, and the humidity was 60%-70%). I thought it was caused by compression during transport or cold damage to the orchid leaves, so I did not pay much attention. I simply soaked them in clean water or dilute potassium permanganate water, and the orchid leaves immediately returned to normal. I moved these orchids indoors for care. At that time there was heating indoors, the temperature was between 20°C-22°C, and the humidity was relatively low, between 25%-30%. The leaves that I had thought had recovered again showed dehydration one after another three or four days later, and gradually the leaf tips showed light brown, and finally the entire leaves turned light black and dropped off, leaving only bare pseudobulbs one after another. Fortunately there were only a few, so I did not pay too much attention. Until around mid-March 2003, when the weather gradually warmed, I suddenly discovered that the leaves of the other newly wild-collectedCymbidium goeringiiplants all showed dehydration and decline to varying degrees (because the weather had been cold and it was inconvenient to go in and out of the shed, I had checked once every one to two weeks). The flower buds that had originally completed vernalization either opened halfway and could not open fully, or bloomed for only a few days before withering again. All these phenomena indicated that there might be a problem with the roots (including some flower buds showing rot), causing nutrients not to be supplied, and of course it was also related to the air humidity being too high or too low. Sure enough, when I repotted and checked, I found that most of the orchid roots had rotted (the orchid roots had turned gray-black, water-soaked in appearance, and broke when squeezed by hand), and there were white hyphae around the roots. All the half-grown seedlings in every whole plant had turned light brown from the base and rotted away. Most of the parent-generation seedlings next to the young shoots were also infected and showed dehydration, and their pseudobulbs also mostly turned light brown. Older seedlings were affected to a lesser degree. Plants that had originally been 4-5 seedlings per clump were left with only one or two old seedlings with incomplete leaves, and those with one or two seedlings per clump all declined. The loss can well be imagined. This should be what the books call southern blight. I actually encountered it. However, personally I feel that the time of onset where I am differs from what the books say. The books say that June-August is the peak period of onset, while where I am, the temperature in the shed in March was not high, only about ten-plus degrees. Coming back to the point, all these orchids infected with the pathogen were disinfected separately with thiophanate-methyl and mancozeb and then planted. The growing medium was also watered throughout with thousand-fold thiophanate-methyl and mancozeb. Only then did I feel the "frightfulness" of southern blight. It is a stubborn and disgusting pathogen. For example, there was a pot of yellow-floweredCymbidium goeringiibrought back at the same time. After returning, it was disinfected and deliberately potted separately in orchid stone, and it also showed the above symptoms. Yet this pot of orchids was thirty to forty cm away from those diseased orchids. It was very likely that I used hands suspected of carrying the pathogen or was not careful during watering, causing cross-infection. Other orchids placed not far around it showed no problems at all. After more than ten days of observation, I felt the effect was not ideal, so I decided to try once more with peat ash water (water mixed in a certain proportion with ash from burned wood). Now, after more than a month of observation, that is, when repotting in early May to check, some individual orchid leaves showed yellowing but had no shoots, some bare pseudobulbs had already sent out small shoots, and some pseudobulbs had all died. Growing orchidsFor more than two years, I have been willing to try many methods of growing orchids, such as using tall plastic pots or purple clay pots paired with orchid stone, immortal soil, and tree fern (unused ones do not need disinfection; used ones are best disinfected), or using clay pots paired with humus soil, as well as using moss alone, immortal soil, and so on. I feel that root and shoot development are still acceptable, and I have never disinfected again, nor have there been major problems. The problem this time happened to arise from the used fine sawdust. Thinking back to how I feared trouble and wanted to save effort at the beginning (it can be said that at the time I did not take disinfection work seriously), it created even more troublesome and tedious procedures now, and the result may still not be good. Now, after every contact with diseased orchids, I am very careful to disinfect all the tools and utensils used before touching other potted orchids, for fear of further problems. I have a bit of the feeling of "once bitten by a snake, for ten years afraid of a rope," and it is even more like the currently prevalent "SARS," requiring attention at all times and in all places. I hope fellow orchid growers will take my example as a warning, and let yourorchidsgrow healthily. This is the original intention for writing this article. In this special period, I hope every orchid grower will face it with a normal mindset and pass through the "SARS" period safely and smoothly. May 14, 2003 Beijing, Ouyang Yanming Unit: Fsuijing City Management Squad, Xicheng District, Beijing Postal code: 100035 Address: No. 25 Xiaocheng Lane, Xicheng District, Beijing Telephone: 66183040 (Before submission, I repotted and checked again, and found that except for a few pseudobulbs that had all rotted, all the rest had sprouted (not yet emerged from the soil), and more than two shoots each; some sent out four or five shoots. In normal circumstances, old seedlings or pseudobulbs in connected plants usually do not easily send out shoots, but in my place several did.)