As human beings we recognize the importance of proper diets in keeping us healthy, but we don’t often consider plant diets in keeping the plant healthy. A proper balance of nutrients is important for plants to fight off many plant diseases. Calcium is one nutrient that increases cell wall strength by increasing pectin. This helps decrease disease invasion. Manganese is important not only because it helps in decreasing disease infecting the plant, but also having the proper form of manganese in the soil can affect the populations of fungi and bacterial in the soil and vice versa. An imbalance can cause an organism to become a pathogen rather than just a saprophyte. Oxidized forms of manganese can serve as a virulence factor increasing the colonization of the host. Reduced manganese works as a cofactor for enzyme systems in the plant to help resist diseases. Zinc can also serve as a cofactor to speed up reactions in the plant which helps in staving off an infection. Copper is a known disease suppressant.
Nutrient levels in the plant can change by environmental factors or by microbial populations in the soil. As the diagram to the right (George Silva, Michigan State U.) shows, those nutrients that have deficiency symptoms in the younger leaves means they are not very mobile in the plant and a shortage or difficulty in taking up these nutrients may make the plant more susceptible to infection.
Infection isn’t necessarily the result of the presence of the pathogen, but rather the level of plant health and the microbial ecology in the soil and the rhizosphere. Shifts in microbial populations can be managed. Call or email us to learn more.