Posted: 12/06/2015 at 13:11
Some roses are more prone to blackspot than others. If you follow the following regime it will cut it down, but it's unlikely to eliminate it. In early spring (March) start by feeding the rose with a rose fertilizer and mulch it heavily with well rotted manure or homemade compost. In April, spray the whole plant and the ground around the rose with a fungicide. Make sure there's no detritus around the base of the rose and there is good air circulation around it. Spray with the fungicide on a monthly basis and keep it well watered, 2 gallons at a time weekly. If blackspot appears, take off the affected leaves and destroy, and respray. If you start early enough it won't take hold so it's a case of vigilance and persistence. As for suckers are you sure they're suckers and not new growth, many people confuse new red stems with suckers which come from under ground. Leave new red stems alone, they'll form new flowering shoots and make the rose bushier. Suckers need to be traced to their point of origin underground and the pulled away from their growing point somewhere on the root system. You can't stop suckers from growing, but I suspect your'e confusing new stems for suckers.