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. However, I knew something other than bad air was wrong with my prized Cattleya Sapphire (this Cattleya is one of the famous "blues" that was produced using C. Ariel coerulea in 1969)...when I pulled the outer layer back from the double sheath it had produced. Opening double sheaths is a normal procedure to assist the blossoms to develop properly. I was surprised when water spilled out after I opened the outer sheath. This is not normal and something you do not want to see. I cut the top of the inside sheath and discovered that it too was full of moisture. I left it open to dry in hopes that the buds would not rot and everything was ok. After the surgery, the buds continued to grow, so I thought the problem was solve and everything was 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 had turned brown and mushy in a very short period of time. Upon further investigation, I became convinced that it was a water mold fungus that had attacked the developing buds.
I suspect the fungus Pythium ultimum was the guilty party. 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. In the next stage of its life cycle the fungus develops a mycelium consisting of thin, thread-like hyphae, which spreads 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 can become dry or mushy as the whole plant starts to have a devitalized appearance.
I knew I had to hurry if I wanted to save my C. Sapphire. I knew this disease was infectious and would spread quickly to other plants in the moist, crowded environment of my winter greenhouse if I did not do something about it.
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