Fungicides Protect Plants, Just Like Insurance

            Do you have insurance? Companies selling insurance are betting you will not have a problem. You, on the other hand, are betting you might. Fungicide use follows the same reasoning. Fungicides, unlike most insecticides and weed killers (herbicides) protect the new growth of plants and keep diseases from starting or spreading. Because the disease doesn’t occur, you may not be convinced it did any good.

            We collectively use the term “fungicide” to describe any pesticide aimed at preventing a disease from fungi, bacteria, virus or mycoplasma like organisms (MPO). Most diseases are caused by fungi but there are a few, like fire blight, which are caused by bacteria and others like Ash yellows or Ash decline caused by MPO’s.

            Desert climates like ours have a low humidity so plant diseases aren’t frequently seen unless we do a poor job choosing plants for the wrong landscape spots, planting, watering, or managing them. Agriculturally Las Vegas is isolated and that also works in our favor. We have far fewer fruit and vegetable diseases here than in agricultural hotspots.

            What can you do to prevent plant diseases? Clean and disinfect tools and equipment. Whether you are doing it or someone else, make sure these tools are clean and sanitized. Make sure supplies you are using are clean. Clean any used pots and containers with bleach and let them air dry for 24 hours before reusing them. Don’t compost diseased plant parts or reuse them. Instead, securely wrap them in plastic and put them in the garbage. If the disease is known to be virulent such as fireblight, get diseased plant parts off the property as soon as possible. Thin out dense plants to improve air movement through their canopies. Whether you are growing tomatoes, fruit trees or shrubs, when they are dense they need to be thinned by selective pruning and growing vigorously to prevent diseases.

Some diseases (biotic, coming from pathogens) I have found in the desert include:

Fireblight – Asian pears, European peers and apples and including many ornamental plants in the rose family including Pyracantha

Fireblight on Asian pear

Root rot and collar rot – many different fruit trees and ornamental trees and vegetables

Chokes the tree or plant at or beneath the soil because the soil is cold or too wet, poor drainage or all three

Ash decline – most ash trees

Limbs dying in established ash trees

Other suspected plant diseases probably encountered are: oleander leaf scorch, Pierces disease on grape, Verticillium wilt on vegetables and, Fusarium wilt on palms and vegetables, white rot on onion and garlic, summer patch on tall fescue, to name a few.

Always use sanitized equipment and sterile soil and containers when possible. By the way, my favorite sanitizer is alcohol after everything has been cleaned with soap and water.