Destroy an orchid if you see wet, dark spots on the leaves and pseudobulbs, as they usually indicate a bacterial or fungal disease, such as black rot or brown spot. Rob Parkers Best is a biocide which will get into the growth & kill the Black Spot permanently, but also has a bleaching agent which will bleach the blackness out of the visible Black Spot. The most common symptom of aphids is the black sooty mould which can be found covering the top of leaves. To work properly it is necessary to ensure that the Rob Parkers Best Patio Cleaner remains on the affected stone for at least an hour, and that during the treatment period the stone surface remains wet. The fungus spends the winter on fallen leaves and also in dormant infections on young stems and buds, producing spores in the spring to infect young foliage. Camellia are easy to grow, glossy evergreens. Spray the plants with the vinegar mixture every morning until the black spots disappear. You can treat with insecticides to control aphids which can damage the foliage on your camellias. Step 1 Combine 3 tbsp. Black spot disease should be treated as soon as you spot it. Step 2 Spray down the infested plant with water from a water hose. Not only does it make the plant look unsightly, but it also causes the leaves to drop prematurely, resulting in weakening the plant if it occurs repeatedly. The fungus produces spores in the black spot lesions on the upper leaf surface and these spread in water to initiate new infections. Black spot is a common fungal problem on roses but can be found on other plants too. The spots can be of various colours – grey, brown or black. Everything you need to know about choosing the right camellia for you. Luckily, it is easy to cure black spots on plants using homemade antibacterial and fungicidal solutions to kill the spots at their source. Description. Get involved. How to grow camellias. Wet conditions are required for the disease to build up, but most summers in the UK are sufficiently wet. The fungi that causes black spot disease favors cool wet conditions and often crops up after excessively rainy seasons. Discover camellias. Their showy flowers come in whites, pinks and reds and appear early in the season; a time when not much else is flowering. Quick facts. Black spot disease is the scourge of rose growers. Discover camellias. of apple cider vinegar with 1 gal. Aphids also attract ants that feed on their secretions. They are ideal for containers. Black spot thrives during hot, humid, or rainy summers and hot days with cool, damp nights. water in a lawn and garden sprayer. Black spot disease is a common affliction of shrubs. Black spot is a fungal disease (Diplocarpon rosae) that affects roses.The fungus develops as black spots on the leaves, which eventually causes the leaves to turn yellow and drop off.Besides looking unsightly, it can seriously weaken the rose plant.