Q.Care of Roses
HELP!! Black Spot (and yellow Leaves) are ruining my beautiful rose bushes and I have done everything I know to do to stop this terrible malady. Could you please tell me something else I can try other than the sprays from gardening stores? They honestly seem to have made the problem worse. I am 82 years old but still love gardening and can’t bear to see my roses in this condition.
Thank you in advance.
Jane D. Naish
Jane, Do you have any agricultural or fine grade kitchen oil? To a gallon of water, add 2 Tbsp of oil and 1 Tbsp baking soda ( some say to add 1-2 drops of dish liquid). This is the "Cornell Formula". Keep shaking the solution in a spray bottle and spray the tops and bottoms of leaves and canes. It is best done on a cloudy day or early morning. Repeat weekly until infection clears and then monthly to prevent black spot. Since black spot overwinters on infected canes, leaves and in the mulch, remove all of these. Good air circulation prevents disease so consider pruning back harder than usual next spring. Invest in a soaker hose if you use overhead watering equipment. Dry leaves are less likely to get black spot. Is the rose in full sun? I'm sorry the other treatments haven't worked. If this formula doesn't work either, at what point is removing the rose and putting in a different plant more satisfying?