Symptoms

• Plant diseases can show up as a variety of spots on raspberry leaves and are often spread by water that splashes up from the soil. Look for round spots with a purple tint to them. Spots can also be grayish and appear as either raised or sunken on the leaf. Examine your raspberries closely and you might notice a gray dust on the fruit, as well as a lower production of fruit.
  
  

Prevention

• The best way to prevent spots from forming on your raspberry leaves is to maintain proper care of your plants. Begin by planting the healthiest plants you find. Inspect your plants throughout the growing season and cut out any canes that look infected. Maintain proper watering requirements for your plants and do not over-fertilize your plants.
  
  

Applications

• If pruning and good routine care of raspberry plants doesn't prevent them from being infected, you can consider using a fungicide application. Lime sulphur is a common application to add in early spring. Other applications can be sulfur- or copper-based and can be purchased and applied according to the package's instructions.
  
  

Relocation

• If a fungicide application doesn't work and spots continue to form, relocating the raspberry plants to another part of the garden or yard might help. Sometimes infections are caused by nematodes that live in the soil, so relocation may eliminate further infection. Continue good maintenance of the plant in its new area and it might outgrow the infection.