Why is my wheat lodging?
The Wheat Team has been busy over the last number of days taking calls and assessing fields to determine why so many acres of wheat are lodging. Most years we observe areas of fields such as overlap nitrogen zones and strong fertility regions lodging, but not very often do we see entire fields lodging, so what is going on? Before we dig into why fields are lodging, we need to understand what factors increase the risk of lodging. Lodging prone varieties, early planting, high seeding rates, high stand counts, strong background fertility and high nitrogen rates can all increase the risk for lodging.
Let’s take a trip down memory lane to last fall; a large portion of the Ontario winter wheat crop was planted in September. The plants tillered extremely well and our over-wintering loss was extremely low. Prior to the wheat “actually” breaking dormancy in March there was lots of hype in the countryside to get out and put some “ultra early” nitrogen on. This made the wheat look extremely good, but in some scenarios it over-stimulated wheat that did not need to be stimulated. The only time we should be considering March applied N is when you have virtually no tillers or you are working with poorly drained soil where there is a risk of not getting the N+S on if the weather turns.
During this timeframe in late March and early April a lot of nitrogen was being applied in one shot; this can also over stimulate plants that already had high tiller counts, increasing the risk for lodging. As we progressed through April into early May, most of those looking to apply their second nitrogen app got it done with ease around GS 32. During this time, the amount of nitrogen loss was minimal. From May 4 to May 15th daytime temperatures were below 15°C and nighttime temperatures were less than 5°C. Although wheat is a base 0 °C crop, it was slowed down quite a bit from this drop in temperature. From the 15th on, the temperature increased substantially, and wheat got kicked into high gear causing rapid growth and stem elongation, especially when we had nighttime temperatures of 20°C. This attributed to weak stems.
Let’s fast forward to this past weekend (June 26). Most of the province received rain from this system that came up from the south. Some areas received way too much rain, other received the perfect amount and for some this rain was a saving grace as it has been extremely dry in certain regions. In these areas, this past system was the most rain the wheat crop has seen for quite some time. The dry conditions have also led to weak stems and it does not take much to lodge a crop with weak legs. Also note that the wheat head will be at its heaviest during this stage of development.
Every field and situation will be different as to why lodging occurred. The most common theme so far is over stimulation of a lodging prone variety planted at a high population. In these scenarios plant growth regulators did help but some lodging still occurred.
The more tricky ones are when a non lodging prone variety lodged under “normal” nitrogen management. In these scenarios the cause is more likely to be environmental. Look at past crop history, background fertility, nitrogen timing and application, diseases pressure (was there powdery mildew), fungicide application, pgrs etc. The answer is not always black and white although it could be multiple factors working together that have caused the lodging.
There are some producers that are growing varieties with good standability ratings and have pushed upwards of 145lbs/ac actual nitrogen without a pgr and the wheat is standing excellent.
PLOT LEARNINGS WITH PGR
Our research plots tested PGR’s with some varieties to determine standability. The goal was to get some lodging – and we were successful. 2.4 Million seeds/acre and 200 units of N were applied in the pictures in hopes of testing the legs of new PGR technology limits. As expected, variety selection is still a very important piece of the puzzle. Blaze stood both with, and without a PGR. Pro 81 needed the assistance of a PGR to remain standing, and CM 614 went down in both scenarios. Yield results and more coming after harvest!
Pro 81 stood well when treated with PGR (front) and lodged with no PGR (back
Depending on how lodged the crop is, some may stand back up but be prepared for a slow harvest. Ensure your knife on the header is in good shape and able to cut tough straw. Be cautious of quality issues that may arise from lodged wheat and most of all be safe harvesting this year!