Smoggy inversions during the winter are common where I live and the terrible air quality can really cause havoc on my beautiful blooms. The sepals curl and turn brown and the flowers just give up and die prematurely. During the winter I learn to expect this.

   I knew something other than bad air was wrong with my orchid when I pulled the outer layer back from the double sheath it had produced. Opening double sheaths is a normal procedure. The problem this time was water spilled out that had formed inside the sheath, something you do not what you want to see. I cut the top of the inside sheath to allow air to enter and it was also full of moisture. I left it open to dry in hopes that the buds would not rot and everything was OK. The buds continued to grow so I thought everything was going to be just fine.

   When the Cattleya bloomed I was struck with the reality that I had not prevented the damage to the buds after all. The flowers never opened fully and only lasted a few days before completely falling off. The flower sheath turned brown and mushy in a very short period of time.

   Upon further investigation I became convinced a so-called water mold fungus, Pythium ultimum, probably caused the infection. This fungus exists only in environments where there is free water.

   It has mobile zoospores which swim in water and on reaching the plant surface these mobile spores penetrate into the plant. Which I believe happened to the developing buds.
In the next stage of its life cycle the fungus develops a mycelium consisting of thin, thread-like hyphae, which spread fast in the affected plant tissues.

   The first visible signs of the infection are small, watery, translucent spots soon expanding and changing to brown. Affected parts become dry and the whole plant may take up a devitalized appearance.

   I knew I had to hurry if I wanted to save Cattleya. This Cattleya is very dear to me and is one of the famous "blues" that was produced by Jones and Scully (I think) using Cattleya 'Ariel Coerulea' in 1969. I knew this disease was infectious and may spread quickly in overly moist environments overcrowded with plants, which is exactly what my greenhouse is in the winter. Many of my orchids that I grow out doors in the summer are moved to the greenhouse for winter. The cold outside temperatures and warm air inside the greenhouse keeps the humidity very high and produces condensation, which drips from the ceiling of my greenhouse.

   It is important to know that while high temperature in general favors fungal infections, alas, Pythium ultimum can be active at rather low temperatures, even in cool greenhouses. The flowers wilted due to the infection to the inflorescence that feeds the flowers.

   I quickly put the plant in quarantine away from all my other orchids. I then preceded the surgery and the necessary steps to try and save the plant. I cut back the inflorescent/tip of the effected pseudobulb down to the healthy green firm growth, I removed about 1/2" of diseased tissue.

   I then went to the barbecue pit and took a charcoal briquette, grinding it into a fine powder. (No need in buying expensive medicines.) The disinfectant powder you can buy to treat minor bleedings or ground cinnamon will also work. I dusted the exposed cut surface with the fine charcoal and replaced the plant on the quarantine rack. I stopped watering and will only water as necessary in the next few weeks.

   Always try to save the pseudobulbs even if you have to cut it back. At the base there are quiescent buds from which new growth will emerge. In some cases cutting back the top of the bulb will activate the buds promptly resulting in new growth.

   In the meantime one of my Dendrobiums, 'Burana Jade' became infected with the same disease. This was caused from water dripping into the center of the plant, from condensation on the roof of my greenhouse. I preformed the same procedure on the Dendrobium as I had on the Cattleya.

   The damage was much greater since it was in the main crown of the pseudobulb. I treated the Dendrobium by cutting away all the growth that was infected and treating the infected area with ground charcoal in hopes that I would be able to save this pseudobulb and stop the disease from spreading to the other pseudobulbs that were growing in the pot.

   I also added another fan to keep the air moving which helps the stagnant cool air and dries the leaves of the plants; the extra fan has really helped with the condensation I have been fighting in my greenhouse.

   Three weeks later I was happy to see I was able to save my beautiful Cattleya. The cut had dried and I knew the infection had been stopped.

   Unfortunately I lost the pseudobulb on the Dendrobium. As can be seen in this photo the pseudobulb continued to decay and finally dried up. I was successful stopping the disease from spreading to the other growths so the plant will be OK.
   Remember this disease is contagious and can spread! At the first sign of problems you must react or in a very short time you could lose your entire collection.

   After discovering this infection I also started to spray my greenhouse and all the other plants with a disinfectant. I personally use RD-20 fungicide and I really like it but there are many other brands, which can be equally suitable.

   Be sure to wash your hands and sterilize all equipment used and remove the infected parts you removed from the orchids.