Roses need a lot of care in spring to ensure they grow properly, but gardeners need to pay close attention to their leaves in the upcoming weeks. The warm, rainy showers in April create the perfect conditions for black spot disease, a fungus that travels through water.
This infection will start at the bottom of the plant with round black blotches around the leaves, which will eventually turn yellow and fall off. In humid weather, black spot disease spreads quickly and will greatly weaken roses to stunt their growth.
Black spot will not outright kill roses, but it will greatly stress them out and direct all the plant’s energy into fighting the infection instead of growing flowers.
Roses with the disease are unlikely to produce any blooms, and the ones that do manage to grow will be small or misshapen.
Weak roses are more susceptible to pests and other diseases that can make their way into the garden and will kill roses if the plant cannot fight them off.
How to stop black spot disease from harming roses
Do not be alarmed, as it is very easy to prevent black spot disease if roses are pruned yearly, as having more airflow around the plant will keep it dry and stop the spores from spreading.
Make sure you are also only watering rose around their base as close to the soil as possible as wet leaves will make the plant very vulnerable to infection.
However, if your roses do become infected, then Kevin Lee Jacobs, a gardener and founder of A Garden for the House has shared the “smartest” way to control it is with cow’s milk.
Kevin said: “A spray composed of one part milk and two parts water is the best answer to the disease. When applied weekly, the solution controls blackspot as well as any synthetic fungicide, including Chlorothalonil.”
It may sound strange at first, but cow’s milk contains natural proteins and enzymes that have antifungal properties, which can kill the spores.
Milk works best when exposed to sunlight, as it creates an environment that is less hospitable to fungus and will also create a thin coating that will stop the spores from sticking to the plant.
Kevin added: “Spraying is work, but it isn’t hard work. Just be sure to wet both the top and bottom of the leaves. Pick up any fallen leaves, too. Otherwise, the spores of the fungus can splash back onto the rose during a rain storm.”
After spraying his roses with the milk solution, Kevin was happy to report that it “really works” to get rid of the disease.
Cracked corn that is fed to chickens can also amend the soil to keep your garden healhy and your roses free of this pesky fungal disease.