DEER: One of the nice things about dahlias is the fact that deer do not like to eat them. They will devour your garden and leave your dahlias alone!
However, there are other pests that LOVE to eat or destroy dahlias. They are:
SNAILS & SLUGS- They will begin eating your dahlias before they even show through the ground. Slugs and snails will eat the new sprouts, holes in the leaves, and they will even eat the stalk. Use slug and snail bait for 2 weeks after planting and continue to bait throughout the season.
SPIDER MITES- The most common predator to dahlias. Typically looks like your plant needs more water. Most plant will begin with yellow spots on the leaves and then the leaves will begin browning completely, working its way up the entire plant. Spider mites thrive in hot weather and can attack certain varieties, while not bothering others. We recommend preventatively spraying beginning in late July and continue to spray through September. Recommended sprays: Malathion (good for prevention, but does not work as well on infested plants), Bon-Neem, or any other Miticide or spray listing spider mites.
EARWIGS & CUCUMBER BEETLE (similar to a lady bug, but green instead of red)- They are mainly a nuisance, while eating many petals of the blooms, they are really not hurting the dahlia plant itself. They fly or crawl in daily and are very hard to control. Recommended sprays: Sevin Dust or Concentrate, Go West Meal, or any other chemical listed in helping with these insects.
GENERAL INSECTS -Recommended sprays: Orthene, Malathion, or Bon-Neem
MILDEW- Most commonly shows up in the fall. The leaves will begin to get a white powdery mildew or spots on the leaves. We do not believe that this is caused from over head watering, but rather weather temperatures and humidity. We recommend preventatively spraying before this issue arises, begin spraying in late July and continue through the fall. Recommended sprays: Daconil, Funginex, or Fung-onil.