BUD BLAST, FLOWER BLIGHTING AND FLOWER DEFORMITY
By Lois Walters - Noosa District Orchid & Foliage Society
Recently I was asked why buds turn yellow/brown and fall off the raceme before opening or the flowers start to open, but never do. As I was a bit stuck for an answer, I decided to do some research and found out lots of interesting information.
When buds turn yellow and fall off, it’s called bud blast and is a common occurrence and has many causes, mostly environmental. It can be caused in the transportation journey from the nursery to your greenhouse through delays in postage, hot cars, etc. e.g., significant temperature, light and humidity changes.
In established collections, buds can shrivel and drop off because of changes in the weather or changes when you move the plant from one position to another in your greenhouse (hotter, cooler, lighter, shadier, etc.) Poor root condition can cause bud drop, as well as lack of water or too much water. Repotting your plant whilst in flower can also be a contributing factor to bud loss.
Blasting can be caused by pests – mealy bugs, aphids, thrips, ants and small caterpillars chewing into buds causing them to abort. If you grow your Phalaenopsis inside, make sure your plant is not near heating or cooling devices and keep away from ripening fruit as this emits ethylene gas as it ripens, causing buds to drop or ripen prematurely.
With flower blighting, insecticides, pesticides and fertilizers (if made up too strongly) can cause a burnt appearance on flowers with browning around the edges or dry spots on the buds.
A big problem a lot of us have is with flower malformation within a dry sheath (CATTLEYAS). The flower sheath grows and turns brown. Why does this happen – maybe the plant is immature or it can be caused by moisture getting in the sheath and rotting the flower buds or perhaps the plant just runs out of energy and aborts flower production. However, some orchids flower from a dry sheath (they rest for a while after forming the sheath), so don’t be in a hurry to cut the brown sheath off before checking what’s inside.
Obviously there are many reasons, but I hope the above information may be of some use.