- The yield response to fungicide applications in corn depend on several factors, one reason why we observe variability in yield responses across fields and regions
- Weather conditions such as temperature and humidity drive pathogen development over time
- Field history and farming practices can affect initial pathogen load and disease development
- Hybrids rated susceptible or moderately susceptible to important foliar fungal diseases are more responsive to fungicide applications than resistant hybrids
碳水化合物 & 组织健康
The majority of carbohydrates needed for grain fill in corn come from the foliage above the ear leaf, 还有耳叶下面的一两片叶子. Experts estimate that nearly 90% of carbohydrates come from these tissues. 因此, ensuring that these tissues are healthy and able to function optimally is an important factor in maximizing yields. This is a major reason that foliar fungicide applications to corn around the VT to R1 growth stages result in the best yield protection; however, 反应的大小可能不同. Foliar fungicides can protect the foliage from foliar fungal pathogens that infect green plant tissues can reduce the total availability of carbohydrates for approximately a three-week period after application.
天气对疾病的影响
The weather before and during grain fill is a key factor in driving yield responses to fungicides. Air temperature, rain events, and relative humidity drive pathogen development and spore release. What weather is encountered can facilitate the development of some diseases over others in each location. 例如, 北方玉米叶枯病, 常见的生锈, 而焦油斑是在较低的温度下形成的, whereas grey leaf spot (GLS) and southern rust thrive in warmer conditions. 然而, 说到水分, high humidity environments are a common factor for foliar disease advancement and potential yield loss.
树冠的高湿度持续的时间越长, the greater the likelihood is that foliar diseases will continue to develop. 因此, yield response to fungicide applications tends to be higher under high moisture environments, where rainfall or irrigation is prevalent during the late vegetative to early reproductive stages. Differences in when high moisture occurred in relation to crop development is a major reason why we see varying yield responses to VT fungicide applications across the region. Some areas may receive higher than average rainfall during the late vegetative and/ or through the reproductive stages of development receive while others remain dry.
A second important factor that plays a major role in crop response to a foliar fungicide is field history and production practices. 焦油斑等疾病, NCLB法案, and GLS overwinter in the Midwest in and on the previous years infected corn residue. 因此, 有这些疾病病史的田地, 在玉米连续生产中, and minimal or no till systems have a greater likelihood of seeing a pronounced yield response to a fungicide as opposed to rotated, 耕种土地. 基本上, the more surviving corn residue that was infected with the pathogen in the field, the more potential pathogen inoculum is available to start a disease epidemic if the appropriate weather occurs.
领域的历史 & 生产实践
The last component that impacts response to fungicides is the susceptibility of the crop to common, 居民的疾病. 整个地区, GLS is by far the one of the most common disease that drives fungicide applications in corn. Hybrids rated susceptible or moderately susceptible to grey leaf spot tend to be more responsive to fungicide applications and result in a positive yield response compared to moderately resistant or resistant hybrids. 事实上, university recommendations will abstain from encouraging fungicide applications on resistant hybrids because grey leaf spot severity will most likely not build to damaging levels. 然而, in situations when grey leaf spot is not the only fungal disease with the potential to damage yields, 使用杀菌剂可能仍有好处. This is due in part to the fact that there are other diseases that can potentially build and develop, and high yielding hybrids likely are not resistant to all of the various foliar diseases that may be encountered, 或者很少有杂交品种能够抵抗所讨论的疾病. 一个很好的例子是受焦油斑或南方锈蚀影响的地区, where a fungicide application during the early reproductive stages provides significant yield protection in areas with little or no incidence GLS or other fungal diseases. For more information on disease management including fungicide and hybrid selection contact your local fs crop specialist.