Disease Causes

• Bacterial wilt causes dark spots on the leaves and peppers and is the probable cause of the brown spots on your pepper plants. Other random viruses may cause streaks and mottling of the leaves, as well as curling or puckering of the leaves. The blossoms may drop, failing to produce fruit, or fruit may have deformities.
  
  

Solutions

• Unfortunately, there is no cure for the diseases that infect peppers. Remove affected leaves and stems. If the plant is otherwise healthy, it may recover. Remove a severely infected plant and destroy it so it doesn't infect other plants.
  
  

Prevention

• Plant disease-resistant varieties such as Yolo Wonder, especially if you live in a hot, humid area prone to plant diseases. Rotate the crops so they don't grow in the same location every year. Plant peppers in an area with full sun because damp, shaded locations support the growth of bacterial spot. Water peppers early in the morning, using drip irrigation or soaker hoses, if possible, because wet leaves spread the disease. Avoid working in the garden when the leaves and soil are wet.
  
  

Insects

• Aphids and other insects don't cause brown spots on leaves, but they can spread the disease from leaf to leaf. Control aphids to control bacterial spot. Look for small, green, black or brown bugs under the leaves. You may also notice honeydew, a sticky substance secreted by the insects on the leaves or soil. Spray the undersides of the leaves with a stream of water or spray the insects with insecticidal soap.