Is a fungicide just a fungicide?

What is the difference between a fungcide and a Plant health Fungicide?In typical Indiana fashion the weather has jumped all over the place, cold, hot, wet and dry. Now growers wonder what the future holds for their crop as we race to the end of vegetative growth stages and head towards tassel and flowering. Many may wonder, if there is no disease out there why do I need a fungicide?
The words Fungicide and Plant Health are often used interchangeably and immediately many growers think of disease control. Yet, while all fungicides are designed to provide some level of disease control only a few provide plant health benefits above and beyond disease control
Back in 2008 Headline Fungicide was the first fungicide to be awarded a supplemental Plant Health Label from the EPA. The label does not discuss disease control at all but rather states: Plant Health Benefits may include improved host plant tolerance to yield robbing environmental stresses, such as drought, heat, cold temperatures and ozone damage. Headline can improve utilization of nitrogen and can increase tolerance to bacterial and viral infections. These benefits often translate to healthier plants producing greater yields at harvest under stressful conditions. The label goes on to mention specific benefits for crops including: improved straw strength and better harvestability for wheat, improved stalk strength, better harvestability and induced tolerance to stalk diseases from corn and better seed quality and more uniform seed size for soybeans. These may seem like bold claims to some but remember that the EPA does not allow claims that cannot be backed by research to be placed on a label.
So where does all these benefits come from. The source is the active ingredient F500 that is in Headline®, Headline AMP®, Nexicor®, Priaxor®, and now Veltyma® and Revytek®. This active ingredient uses its effect on cellular respiration to positively influence the plant in addition to the disease control it provides. These benefits show up in two main areas stress tolerance and growth efficiency. For this article we will focus on the stress tolerance benefits
So what is stress tolerance exactly? Well, stress tolerance is simply how the plant deals with stress. Besides the obvious stress caused by a disease infection other types of stress we see in our crops include increased ethylene production and more reactive oxygen species being present within the cell. The role of ethylene in the plant is to signal the plant to shut things down and begin to move towards maturity. When a banana on your counter turns brown it is ethylene that signals that maturity of that fruit. You can even buy bags to put your fruit in called “ethylene bags”. These bags help reduce ethylene and slow ripening. The same thing is true in your crops. When stress increases ethylene production, the crop begins to mature before it has fully finished its grain development. Unfinished tips of ears in corn are one example as well as fewer seeds in a soybean pod or small or missing kernels on a wheat head. Also when stress occurs reactive oxygen species (ROS) can increase in the plant cells and the more of them there are then the more destructive they are to the plant cell. You may have seen Anti-Oxidants in the health food and beauty care products at the store as they are promoted to reduce the number of these reactive oxygen species within our bodies. Regardless whether it is plants or humans, reactive oxygen species are recognized as a symptom of stress and are not beneficial in any way.
Fortunately, there are products available to help combat both ethylene and ROS. BASF Plant Health products like Headline Amp, Priaxor, Revytek & Veltyma reduce both ethylene production and reactive oxygen species. By suppressing ethylene production this allows the plant to reach physiological maturity and preserve yields. Infrared imagery shows that plants treated with BASF Plant Health products maintain cooler canopy temperatures than untreated plants. (Figure 1)Cooler temperatures are the result of stomates on the leaves that stay open when they would normally close under stress. Stomates are like a thermostat for the plant and regulate important gas exchange processes like transpiration. When plants are suffering drought stress, stomates close in "order" to protect it from further water loss but this closure not without consequences as it also limits other important gas exchange functions within the plant. So by keeping the stomates functioning properly even in stressed conditions you can maintain a cooler canopy for your crops. Consequently your growth efficiency is increased curing stressful conditions which then often translates into increased yields.
Reactive oxygen species numbers are increased when the plant is subject to stress such as drought and heat. When stomates (the same ones we mentioned with ethylene) are closed due to stress this can allow levels of ROS to increase and overwhelm the natural numbers of anti-oxidants normally found in the plant. BASF plant health fungicide applications allow for an increase in anti-oxidant production therefore holding down the ROS numbers and allowing the plant to continue normal growth and development. Greenhouse work at BASF has demonstrated that protecting corn plants with Plant Health products prior to applications of ROS increasing chemicals resulted in a significant reduction in ROS and the protection of normal growth and development. (Figure 2)
The last few weeks in Indiana have had a variety of temperatures with plenty of warm days mixed with a few cool ones.. Early season precipitation has kept much of the corn crop in decent shape but in 2-3 weeks we will be in a very crucial stage, reproduction. During reproduction the crop will be need protection from further heat stress. This is where Plant Health comes into play. If disease were to show up this would only make matters worse as now you have heat stress combined with another stress, disease. If you were worried about if justify spraying a fungicide for disease control this year, the reality may be…. “Can you justify not using a Plant Health fungicide this year” given the environmental conditions we are seeing in the fields.
Remember…. Disease may not be present every year but when you use a Plant Health product like Veltyma, Revytek, Headline Amp and Priaxor you know you are getting Plant Health every year.