how to deal with black spot leaf disease hello and welcome to videojug we're at Capel Manor College in Greater London head of horticulture and landscaping tom cole is going to show us how to deal with black spot this leaf disease attacks plant throughout the year but is most prevalent during dry months if left untreated black spot spreads rapidly and weakens plants severely step one you will need secateurs and if you want a good combination pesticide and fungicide spray available from garden centers step 2 identify the disease the symptoms of black spot are small round black patches ranging from one millimeter to one centimeter on the upper side of the leaf the tissue around the spots turns yellow and the leaves fall prematurely step 3 cultural control as soon as you see any signs of black spot remove the infected leaves with the secretaries or by hand gather all the debris from around the base of the plant to burn the leaves and debris or throw them away never put them in the compost heap as this will spread the disease do this throughout the year whenever black spot occurs step four chemical controls some gardeners use spray to control black spot for the best results this should be applied after cultural controls but may be the option of removing all the diseased leaves would leave your plant bare always follow the instructions on the spray container hold the bottle about 30 centimeters away from the plant and spray enough to coat the leaf but not cause drips treat the plant either early or late in the day so you don't spray pollen spreading insects like bees wait 14 days and then repeat step 5 prevention spraying can minimize spread but it won't stop black spot all together the healthier the plant the less likely it is to catch the disease to avoid black spot in the future keep your plants well watered and fed done you