Overly Thorny Rose Bush
Q: There is an overabundance of thorns on my yellow rose bush, and it looks very strange. What would make a rose bush suddenly start producing hundreds of extra thorns? The blooms are normal, and other than the thorn problem, the bush looks healthy.
A: The first possible cause of suddenly excessive thorn production is rose rosette. This disease is caused by a virus. Unfortunately, there's no cure, and the plants that have this problem will die within a year or two. Infected plants should be destroyed, so you might wish to verify the diagnosis with your county extension office. They might also be interested in tracking the appearance of the disease in your area, if that is what it is.