Buds That Fail to Open
What does it mean when rose buds turn brown and don't open?
Q. I have 130 roses and most perform well by producing many and large blooms. Occasionally, though, buds will form on a few plants and fail to open and brown out on the plant. Do you have any idea why that occurs? I notice it on English roses more than on the hybrids.
– Nipomo, CA
A. Your plants have the symptoms of a fungal disease called botrytis (Botrytis cinerea) This disease prevents the blooms from opening; buds turn brown and decay. Sometimes partially opened flowers are attacked and individual petals turn brown and shrivel. The fungus is always present in rainy seasons when the old blooms are not removed.
Be sure to prune away any infected buds to halt the spread. It will also help to remove spent flowers on a regular basis. Fungicides will help control botrytis. Apply according to label directions; weekly applications may be required during wet springs.