Slime Mold

• Yellow fungi you find growing on mulch is almost certainly slime mold. A slime mold infection usually shows up as a mass of yellow or orange that appears slimy and moist. If slime mold is left alone, it will usually dry out. When this happens, spores release into the air, and the slime spreads.
  
  

Effects

• While slime molds are scary and disgusting in appearance, they are mostly harmless. Slime molds do not cause any diseases in plants, and they are not harmful to humans or animals. Although slime molds themselves are not harmful, they may pave the way for other fungi to invade. Thus, you should remove slime mold from mulch if small children or animals will have access to mulched areas.
  
  

Control

• Ideally, you should remove slime mold in the early stages of infection. Once it dries out, the spores will spread when you disturb it, and the problem could get worse. Use a shovel or rake to remove the mold from the mulch and put it into the garbage. Do not simply move it to another area of your garden, because spores may blow back to the mulch and cause reinfection.
  
  

Prevention

• Fungi love areas with plenty of moisture and little air, so it is vital to ensure mulch receives adequate air circulation. Rake the mulch often to expose more of it to air and to light from the sun. Remove excess foliage from plants where mulch is used to allow sunlight and air to reach the mulch.