Staging Update, Disease Pressure, Sulphur Deficiency, Fungicide Timing, Full shot N at GS32 vs 2nd App N
Traveling across a wide range of counties assessing wheat fields, one thing is certain; getting the wheat crop off to a good start early is imperative. The range in plant staging is unbelievable this year. In Essex County the flag leaf is one third to almost fully emerged in a good majority of fields. In South Huron, some wheat fields planted around Thanksgiving are just at or soon to be at (GS32) two nodes visible. A wheat field planted late September in Lincoln County was at (GS32) two weeks ago and is well on its way to (GS39) flag leaf ligule just visible.
Since most of the province is wet and planting has been delayed, a great management practice for every grower to do is get out and assess their wheat fields. This is a great time to evaluate crop staging and clover establishment (if clover was under seeded). Furthermore, it is a good idea to scout for weeds, diseases, and nutrient deficiencies. Believe me, the weeds are there and are growing fiercely! A couple diseases that many people are starting to find are Septoria,Powdery Mildew, Leaf Rust, and Stem Rust. (LINK to Focus on Fungicide) If no sulphur was applied with the nitrogen application, we may start to see (S) deficiency. With the cool, wet weather we have been getting recently, the sulphur mineralization and plant uptake will be reduced. As mentioned in the previous Wheat News Plus article, (S) deficiency will show on the new growth first whereas (N) deficiency will show on the old growth first. If you are unsure, a good practice to do is to take tissue samples from parts of the field where the crop is lush and green then take tissue samples from the areas in the field that are yellow and pale. Then send the samples to a lab for analysis.
With the difference in crop staging, the management practice will vary from field to field. The growers who are at (GS32) will be looking to put their second shot of N on and apply herbicide and fungicides. The growers who have fields at (GS39) need to be very careful not to damage the flag leaf. Herbicides should not be applied once the flag leaf is visible. UAN application becomes risky once the flag leaf unrolls and lays open, application is tricky but can be done, but be sure to avoid burn. Dilute the UAN with water, apply when cloudy, and if possible, apply ahead of rain.
A management practice that I have heard more than once in the last couple weeks is waiting until (GS32) to put all the nitrogen on. I know there are certain areas that could not get on the fields due to wet conditions but this is what happens when growers only want to do one shot of N and delay it as long as possible to get the best bang for their buck. I completely understand but I am afraid some of those growers have sacrificed yield as a result. Again and again, split applying N not only reduces lodging risk but it also reduces the risk of N loss and the risk of not having any N on and letting the crop go backwards. If all the N has been applied already, we risk losing N through leaching and possibly denitrification if fields remain saturated and the temperatures start to increase. The fields that received all or just a shot of N early look top notch but the question I ask is how much N is lost? The growers that are coming in to do their application at (GS32) are generally using UAN 28% with a sprayer. They are either following the tracks from their first application or they are making their first set of tracks because dry was used upfront. Using a sprayer will greatly reduce the amount of wheat that gets tramped. If growers plan on using dry from now forward, application should only be made with a high clearance wide spread pattern machines with narrow tires. . The yield impact from equipment with a wide footprint varies from 5-55% loss where the equipment drives. There are multiple factors that dictate the yield loss such as soil conditions, time of day, temperature and weight of the machine. The wheat crop looks fantastic, please do not “steam roll” it over.