Botrytis, otherwise known as gray mold, initially occurs as pink spots on light-colored flowers. These might turn yellow or dark brown with age. Flowers may fail to open, or may just rot. Leaves also rot. You can see a grey mold on the plant, and it may also attack the base of the plant where it contacts soil. Gray mold loves moist and cool temperatures. As soon as you see grey mold, you must cut all infected parts off the plant and destroy them.

The fungus Sphaceloma rosarum or Elsinoe rosarum is called Purple Spotting or Spot Anthracnose fungus. It appears as red, purple, pink or brown spots on leaves and stems. In advanced condition, the leaves turn yellow and drop off.

Another fungus is called Rose Wilt or Verticillium Wilt. This fungus lives in soil and prevents the plants from uptaking water from roots into the plant. During hot conditions, the disease becomes obvious, with wilting and yellowing of leaves a prevalent symptom. Eventually, the entire plant is defoliated and dies. Verticillum can get out of control quickly, and most growers are forced to yank infected plants and destroy them.

Check out the link here to solve your gray mold and rose wilt problem

Flower Gardening | Advanced Nutrients Articles