the leaves fell off and canes turned brown on rose bush
My rose bush has been in the ground for 3 years. This year the leaves fell off and canes turned brown. The root system consisted of a huge root ball with no feeder roots. What could have caused this problem? Had low 40 degree weather in April and May. This is unusual for this area.
It could be that you had rose nematodes that destroyed the feeder roots. They are very small eel-like round-worms. Their actions upon the root systems of rosebushes cause the roots to not be able to take up water or nutrients needed by the rosebush. Controlling them can be very difficult. One organic method is to plant marigolds in the same garden area as the rosebushes and the marigolds will suppress the nematodes. The roots of the marigolds put out a substance that is toxic to the nematodes. Plant the marigolds all around the rosebushes effected. Another form of control is called Solarization. Solarization is the use of heat from the sun to heat up the soils enough to kill the nematodes in bare soil. This technique involves placing clear plastic on moist (but not wet),tilled soil. The edges must be well-sealed by burying them to a depth of 6 inches, so that the trapped heat does not escape and to prevent loosening by the wind. Apply the plastic in June or July and allow it to remain in place for a minimum of six to eight weeks. Do not remove the plastic until you are ready to plant. This method heats up the soils to the point where the nematodes cannot survive.
Nemastop is another organic method of nematode control.
The only other thing I can think of that would do this is if some chemical was poured on the soils of perhaps dogs urinated on the soils around the rosebush. Burning the tender feeder roots and killing the rosebush.