Sep17MonField Notes September 17, 2018 Wayne Becker, Southern RSM
Balanced fertilizer applications may reduce the need for chemical disease control in some cases. Scientists who breed crops are continually attempting to develop new varieties that are resistant to pests and disease. The big challenge is that pests and disease continually adapt to their environment, which inevitably cause resistant varieties to fail and become susceptible to pests and disease.
Even though genetic resistance is the primary path to pest avoidance, environmental factors also play a huge role. Plant nutritional status is one of these environmental factors. Usually a balanced nutrient supply ensures optimal plant growth and also pest resistance.
Balanced plant nutrition is key to using plant nutrition as a tool to minimize crop pests. Often over application of one nutrient may induce deficiency of another, especially potassium, which could lead to increased disease occurrence. This is especially true when it comes to nitrogen. Often farmers mistakenly over-apply nitrogen in an attempt to increase plant growth. While maintaining adequate N is essential for healthy crops, excessive N can promote many diseases and insect pests.
Potassium is one of the most notable nutrients involved in maintaining crop health. K deficiency increases susceptibility of host plant to blight, rusts, and even possibly Fusarium. Potassium deficiency reduces the synthesis of proteins, starch and cellulose. However, there is no need for K levels to be increased above optimum levels.
Phosphorus is also important. Even though it is not one of the primary nutrients known for decreasing disease, it has been known to suppress take-all in wheat, and foliar applications may be effective against some airborne pathogens.
Additionally, secondary and micronutrients also play a role in increasing plant avoidance of pests and diseases. Ensuring sufficient amounts of Ca, B, Cu, Zn and especially K enables plant cells to ward off pathogenic invaders because they create plant cells that are less penetrable. Also, N, P, Cu, and Mn have been noted to decrease severity and incidences of Soil-Born Fungal and Bacterial disease.
Nutrient supply changes the resistance of plants to pathogens and pests by altering growth and tissue composition. Effectively timing and placing quality sources of nutrients may lead to benefits for farmers that go well beyond maximizing growth and development of crops.