Garden Word of the Day
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Do you remember the fire safety lesson from elementary school where they told you that three things had to be in place for a fire to occur? [The answer is fuel, heat, and oxygen.] Take any one of those components out of the equation, and voila! No fire. Well, plant diseases work much the same way.
The three sides of plant disease
For disease to occur, the environment, host plant, and pathogen must all be present. Alter any of those three and make infections less severe and less frequent. Remove one side of that triangle to eliminate the disease. Since prevention is far easier than treatment, the disease triangle is a handy tool for you to use in the garden.
You can control common environmental factors with these good cultural practices:
The host is the plant that gets sick. It can also be a plant that shelters a pathogen or disease vector. Some diseases affect only a single host, while others can infect many different types of plants. [Did you know that lilacs grown near apple trees are more likely to get bacterial blight?] Protect host plants from disease with these tips:
Pathogens are disease-carrying bacteria, viruses, or other microorganisms. You may be surprised to learn that many pathogens are already in your garden. New arrivals are unusual and notable, which is why quarantines are so effective at protecting your plants.
If they are not present, pathogens may catch a ride into a landscape on insects, tools, shoes, and newly acquired plants. Chewing insects may create a point of entry for disease or may be infected, transferring viruses or bacteria to the host plant as they feed. You can interrupt the pathogen side of the triangle with these tips:
Many botanists have added time as a factor in disease prevention, converting the disease triangle into a pyramid. They do this because time can be a critical factor in disease development. Diseases take time to infect a plant and reproduce. Water sitting on a leaf for a few minutes may do nothing, while several hours of surface water on the same leaf may be deadly. Regularly monitoring plants for signs of disease can put time in your favor.
How healthy plants defend themselves
If all the disease-carrying pathogens are already present, why don't all plants die a horrible death as soon as they sprout? Like us, plants have evolved ways to protect themselves. They do not have immune systems. Instead, they use these steps in a type of chemical warfare:
All this time, you probably thought plants were relatively passive, right?
Symptoms & disease identification
Plant disease symptoms include wilting, stunting, deformed leaves or other growths, cankers, chlorosis, and more. If you notice disease symptoms, use that information to determine the cause. Contact your local Master Gardeners or the Department of Agriculture for advice. Once you know what your plants are fighting, you can use the disease triangle to break the cycle.
Each microclimate has its own set of problems. Learning about your plants puts you in control.
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