Black spot is a pernicious leaf spot disease that is best prevented. Many roses are prone to this malady that starts as small black feathery spots that enlarge and eventually turn your leaves yellow, and finally all the leaves fall off your bush. If your roses loose all its leaves several times in the same year, its health will be compromised.
If your rose is tolerant to this disease you can cut off the few diseased leaves, however, if most of your rose bush is blighted by black spot you will need to either spray it every few weeks with a fungicide, or shovel prune it and buy one of the newer disease resistant roses.
Spraying need not be bothersome. Use a 1 or 2 gallon pump sprayer. Measure how much water you will need to spray, depending on how many roses you have. Add a few drops of soap (like Dr. Bonner’s castile soap), plus 1 tablespoon of white vinegar (this is for 1 gallon of water, adjust according to the water amount used), add your systemic fungicide and your contact fungicide. Stir to mix. Spray the bottom of the leaves, moving the spray wand side to side, then from top to bottom.
If you spray faithfully every 10 to 14 days you will have clean leaves and a very healthy rose.
Do an internet search for Diplocarpon rosea site:edu if you want to learn more about black spot.
Email us at greenvillerosesociety@gmail.com for specific fungicide recommendations.
