By: Mitchell Japp, MSc, PAg, Provincial Specialist, Cereal Crops
Fusarium head blight (FHB) devastated many durum and wheat crops in 2016. Barley, oats, rye and canaryseed were also affected. Growers have been challenged over the winter to market grain with fusarium-damaged kernels and grain containing mycotoxins like DON (deoxynivalenol, also known as vomitoxin). Growers want to avoid a repeat of 2016, but may now be wondering if a fungicide application will be economical.
Unfortunately, with FHB, clear answers are difficult to come by and management needs to go beyond fungicide applications.
At this time of year, we are past making management decisions such as crop rotation and selecting varieties resistant to FHB. Management is now focused on using fungicides in conjunction with risk maps.
FHB is a mono-cyclic disease, so once symptoms are present it is too late to treat with a fungicide. Fungicide application decisions must be made before infection occurs, to coincide with the growth stage when the crop is most susceptible to infection – anthesis (flowering).
Fungicides are not applied for free, so they should be used when there will be a value in using them. Fortunately, there are tools available to help make those decisions. The Saskatchewan Wheat Development Commission works with Weather Innovations Network to deliver FHB risk maps for spring and winter wheat in June and July each year. These maps should be referenced daily as crops are at or approaching the susceptible stage. The risk maps should contribute to determining if a fungicide application is warranted.
Additional factors include local weather conditions that can be missed on a large-scale map. Fusarium spores need 12 hours of high humidity to germinate and infect.
Because FHB was so prevalent in 2016, the disease will be present in most areas of Saskatchewan. This increases the risk, but so far the weather conditions for most of the province have indicated low risk, with some areas showing medium risk.
Understanding the risk is the first step, but then the cost of the fungicide and application should be balanced with the anticipated crop yield and value of the crop. These calculations should be done prior to the crop reaching flowering, so that you can quickly make a decision to make targeted and timely applications that fit the narrow application window.
If the decision is made to spray, the fungicide application should maximize the use of the fungicide. Best practices include using angled spray nozzles, coarse spray, low boom heights, low wind conditions, high water volumes and slower sprayer speeds. FHB fungicides are only rated for suppression, so it is important to make the most of them.
Sprayers101 – Fungicide application in cereal, pulse and oilseed crops
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