Cinnamaldehyde is the organic compound that gives cinnamon its flavour and odour. It occurs naturally in the bark of species of the genus Cinnamomum and is extracted from the bark. One of its main uses is as a fungicide. It is typically applied to the root systems of plants.

I guess, it is stronger than Cinnamom powder and can be used the same way.

Another use of Cinnamaldehyde is as an insecticide and also kills mosquito larvae. Its usefulness for orchid growers as insecticide is practically zero.