Working in dry weather is important for preventing black spot from spreading because the fungus grows better in damp weather.
Dry your pruning tools before storing them so they don’t rust.
There are many fungicides available that fight black spot. Speak with an employee at a local garden store about the breed of rose you have to find the best product for your needs. Look for fungicides with active ingredients including captan, chlorothalonil (Daconil), copper, ferbam, mancozeb, maneb, triforine (Funginex), sulfur, thiophanate methyl (Cleary 3336), and ziram. These are most effective in fighting black spot. Check if there are any restrictions on chemical application in your community before using the spray.
Mix 1. 5 tbsp (9 g) of baking soda, 2 tbsp (30 ml) of vegetable oil, 1. 5 tbsp (22. 5 ml) of liquid hand soap, and 1 gallon (3. 7 L) of water. Load the mixture into a spray bottle. Shake it and then spray all the affected plants every 7 days until the fungus recedes. Commercial sulfur spray is also effective against black spot. This is an organic alternative to other fungicides. Look at your local nursery or garden center for a bottle.
If your roses are not in pots, consider digging them up and replanting them in a sunnier location.
Dig the entire plant out, roots and all. Don’t leave anything behind. Remember to clean up any remnants the plant leaves behind, like twigs and leaves. These can spread the fungus to other plants.
Remember that just because a breed is resistant to black spot doesn’t mean that breed will grow well in your area. Find a breed that’s suited to your local climate. Most yellow and copper-colored roses are particularly susceptible to black spot. Avoid these breeds to prevent outbreaks.
Consider planting your roses in pots so you can move them around to sunnier spots if you have to.
Ask an employee at the nursery what the ideal spacing for your rose breed is. Also prune your roses if they’re growing close to each other.
Clean up your yard especially after it rains. Wet foliage encourages fungal growth. If you have a compost pile, locate it far away from the roses.
Use a sharp pair of garden scissors to get a clean cut through the plant. Prune in dry weather so excess moisture doesn’t enter the plant.
Water early in the morning so the water evaporates throughout the day. If you located your roses in a sunny spot, this should be no problem. The leaves will still get wet in the rain. This is why planting your roses in a sunny spot is important.
Remember that fungicides don’t kill black spot if it’s already growing. They only prevent it from spreading.
If there was mulch on the ground when the black spot started, rake that all away and place a new layer down. The old mulch could be infected with spores.
The most common early symptom of black spot is yellowing leaves. Then the characteristic black spots appear and spread throughout the leaf. Eventually, the leaves start falling off and the plant dies.
