Does anyone have an opinion about the systemic rose fertilisers and which may be best to prevent mildew and blackspot?
Systemic pesticides work by being so poisonous they are able to cross even the barriers to chemicals a plant has, and make the plant sap poisonous to sucking pests. I would rather do without the plant than purchase, handle, apply and store something like this. Same with spraying fungicides. If a rose or any other plant is spoiled by leaf fungi, I get rid of the plant. End of problem. During 2004 The Plant Locator - Western Region (Black-Eyed Susans/Timber, Portland) listed something like 50,000 kinds of plants being offered here. Even allowing for synonyms (more than one name being listed for the same item), that leaves a lot to choose from, and little if any need to struggle with problem-prone selections. There are even disease-resistant modern hybrid bush rose cultivars.
Maybe this will inspire me to get rid of my New Dawn which is now suffering mildewed leaves in a too-protected area of my patio -- not enough air circulation owing to the fence, I am guessing, plus a period of deep shade. In Nova Scotia I grew New Dawns magnificently in partial shade and not a spot of mildew. I will now look for a replacement climber and see if I can avoid using fungicides.
Actually it's the drying of the soil by the concrete foundation. Watering more often might take care of it.
But we have special irrigation, that mini drip irrigation to the roots -- my goodness, more water? I do grant that there is a lot of drainage there, but I planted the roots out further about 2 feet at least away. I think it is the moisture in the air, the lack of breezes... or something. A clematis in the patio suffered from mildew also. There are certain challenges to this West Coast gardening...
