By Norman Wilson, Ph.D.
Crop disease management has been a challenge for farmers since the dawn of agriculture. Early farmers were aware of weather conditions that affected their crops and they could see most insects that reduced yield or quality but crop diseases had no obvious cause and only the end result could be observed. All too often, the end result was devastating crop failure. Because the causal agent could not be seen and identified, plant disease epidemics often took on mythical proportions. The potato blight epidemic in Ireland during the mid-nineteenth century is a classic example of how a crop disease can devastate an entire country and produce worldwide consequences.
Modern plant pathology has come a long way since the Irish potato famine. Today’s grower and the scientific and business communities which support modern agriculture are much better equipped to manage crop diseases. We can identify the causal organism for almost all important crop diseases and growers have an extensive shopping list of disease control products to select from. In fact, a more common concern today is choosing the correct product or products to do the job at an affordable price. The latest generation of disease control chemicals are expensive and tend to be very specific in their activity. An unfavorable experience with an expensive treatment that didn’t work can leave a grower wondering if there isn’t a better way.
In fact, there is a better way but the solution can require advance planning and close attention to the soil and crop. Living organisms, plant or animal, have natural protective mechanisms to ward off disease. Modern medicine and our intuition tell us that we are more susceptible to many diseases when we are “stressed out” or malnourished. The same general principle is true for crop plants. Some of our crop varieties have specific genetic resistance to certain diseases but remember that all varieties of all crops have innate protective mechanisms. Utilizing natural protective qualities of plants and the soil is a less expensive and more rewarding way to manage crop diseases.
Natural disease management begins with the soil. Most crop diseases are caused by microscopic fungi or bacteria and many of these are soil borne, meaning that at least part of their life cycle occurs in the soil or on old crop residue in the soil. Agricultural scientists know that some soils exhibit a natural suppression to soil borne diseases. These soils are well flocculated, relatively high in organic matter, and have elevated levels of soil microbial activity. Do these soil characteristics sound familiar? They should, because these are some of the same soil characteristics that we at ViTech have been promoting from the use of ViTech biological soil products. ViTech ViClout and ViBasic work to stimulate aerobic soil microbial activity. Enhanced microbial activity breaks down old residue into humus, aerates and flocculates the soil, and suppresses soil borne diseases in the process.
Once a crop is planted and growing, the second stage of disease management can be initiated. Nutritionally balanced plants are better prepared to avoid and/or tolerate disease infection. Plant tissue analysis (whole leaf) is a grower’s best tool to insure complete nutritional balance. Attention should be given to micro-nutrients as well as major nutrients. All plant nutrients are important for disease management but research has shown that certain nutrient elements are directly correlated with plant disease resistance. Excessive nitrogen can increase susceptibility to disease infection while elevated levels of potassium, calcium, sulfur, copper, boron, and silica can help a plant avoid infection or reduce the severity of an infection. Plants actually mobilize specific nutrient elements (or compounds containing these elements) to fight disease infection in much the same way that our bodies mobilize white blood cells to fight infection. An example of this type activity would be the strengthening of leaf cell walls at the site of a germinating disease spore.
For best results, a crop should receive a foliar balance prior to anticipated disease pressure. An essential component of any foliar application (nutrient or pesticide) is an effective carrier. ViTech consultants recommend an organic based product called ViCare to carry foliar nutrient sprays or to complement most foliar applied pesticides. ViCare serves an especially important function in a disease management program. Disease control products are typically classified as either systemic or topical. Systemic treatments tend to be most effective but their activity is dependent upon rapid absorption and translocation to infection sites. Carrying a disease treatment withViCare is the quickest way to get disease fighting activity into the leaves and translocated to sites of disease pressure. ViCare makes new chemical based disease control products work harder (lower effective rates means lower cost) or ViCare can be mixed with older disease treatments to achieve enhanced results. Equal parts of ViCare, ViTech Copper, and ViTech Sulfur make an excellent broad based disease treatment that is not crop specific and is equally effective on fungal and bacterial diseases.