My Mill Valley garden is located on a wind-swept westward slope within several hundred yards of the San Francisco Bay. Wind and fog are ubiquitous, as are poor, thin, heavy soils underlaid by bedrock. I expect that many of my roses would look bigger and cleaner in better locations. Raised beds are a necessity to have enough root room for larger roses on the slope. But don't take my word for it. Here's what it looked like before we landscaped in 1997.
I am interested in roses in the landscape. In other words, I don't show roses. I use chemical fertilizers (time-released usually) a couple of times a year, relying largely on soil amendment, mulch and organic fertilizers like Ironite, alfalfa pellets, composted stable bedding, horse manure, fish emulsion and liquid kelp. With the exception of Roundup applied to a couple of weeds I never managed to dig out (mainly a bindweed that grew through my living room wall and fennel that just won't go away), the only pesticides I've used are Neem Oil, Erase (jojoba oil) and dormant spray mixed with horticultural oil -- until the dreadful spring of 2003. I've identified the scourges of that season, finally, and hope to have them eradicated by the end of 2004.
Before April 2003, I hadn't sprayed a rose (or anything else) in over four years. Instead, I cruelly culled out those roses that, whatever their virtues on other gardens, require spraying in my micro-climate. Those that have been banished are duly noted.
But....that spring was different. For the first time, small own root roses were dying. I lost three or four altogether. The pattern was consistent. The sole cane would die back from the the top down. Then I noticed lesions and dieback on several mature roses. We had a long, cold, wet spring, which followed a very mild winter without any frost. For whatever reasons, conditions were optimal for cane cankers, bacterial blight and botrytis.
So in the spirit of integrated pest management, in the middle of spring, with many small own root roses showing signs of distress, I sprayed twice with very effective and not terribly toxic fungicides. The small roses recovered gradually, and the botrytis was confined to only a few roses which I sprayed again. The infection in 2004 was much less severe, and headed toward control.
The moral of this story is that sooner or later, roses will suffer every blight. While avoiding unnecessary chemicals is a virtue, so is using technology for surgical strikes to improve the garden.
