Black spot is actually a fungal disease, causing black spots on the leaves. The disease is commonly found in Australia. There is no specific pattern of this disease, spots appear randomly on leaves and its edges are usually blurred. Initially, they appear at the place where the fungal spores originally landed. The infected leaves turn to yellow and fall off. Sometimes, the infection lead to the stems and destroy the whole plant (in severe cases only).
The infection spreads in no time, resulting into weak plants with lesser flowers and slow growth rate. With this infection, the plants are more vulnerable to other pests and infections.
The disease is common in humid and hot weather. Some plants are more vulnerable to black spots, so if your plant is having a tough time, you can replace it with some other variety, which performs better against the black spots.
Black spot is a very common fungal disease of roses. Some varieties are less susceptible but just about all the popular ones seem to get it.
Organic Control Methods for Black Spot
Best results are obtained by undertaking both the cultural and spray methods.
- Ensure the rose receives at least 6 hours of direct sunlight every day
- Ensure good air circulation around the bush
- Clean up fallen leaves regularly as these can be a source of reinfection
- Water in the morning as residual water will evaporate faster than in the evening
- Avoid watering the foliage
- Feed regularly with an organic fertiliser as roses are hungry plants
- Regular application of eco-seaweed will stimulate stronger healthier growth
Apply eco-fungicide or eco-rose every 7-10 days at the first sign of disease outbreak. Leaves already infected cannot be saved but the spray will create a protective coating over leaves to prevent new infection occurring.
HANDY HINT: We recommend adding a little eco-oil (2ml per litre) to the eco-fungicide or eco-rose solution to help it stick and spread better over the foliage. If you have an insect problem at the same time then increase the eco-oil rate (5-10ml per litre) to create a combined organic insecticide and fungicide spray. Too easy.
Read original article here: http://ecoorganicgarden.com.au/problem-solver/black-spot/