The days are getting shorter, the nights are getting longer, and there is no doubt that fall is upon us. That chill in the air does more than confirm that it's almost playoff time for high school football and harvest is in full swing. It also confirms that it is the end of a growing season. But even though the 2018 growing season is behind us, it doesn’t mean that we get to take a break when it comes to agronomy. We still have an opportunity to manage some activities and applications that can make 2019 easier, and more successful.
Every single year in March we have great intentions for our new Soybean fields. We are going to get a pre-emergence herbicide on them to get better weed control for the growing season and help manage our herbicide program costs. Then the reality of Mother Nature and April arrive. Wet spells, the desire to plant early, and a half dozen other factors take the plans we worked on and tears that plan into tiny little pieces. My question for you is why not a fall weed control program?
Fall herbicides can not only be a great fit for weed control on no-till acres but are perhaps the best way to get a jump on marestail and winter annuals. When marestail is a problem like it is for most of us, then using a program that includes dicamba for fall control works well. You can also add 2 4 D to aid in the control. Timing generally goes from now until the ground is frozen, as long as we do it during daylight hours. The good news is that this type of program gives us the flexibility to still rotate to corn or beans next spring, and with today's genetics in corn and soybeans, we have very few concerns.
Our alfalfa acres also provide us with a few management choices to consider. First of all, when is it too late to take another cutting? Harvesting in October is tricky because we might need the tons, but we don’t want to kill our stand. Research suggests cutting later in the fall is safer than cutting earlier. This is because as October progresses, the plant is storing carbs and proteins in the taproot. Cutting the alfalfa while regrowth is still possible reduces the plants ability to complete this chore. Harvesting it late in the month hedges against those conditions.
While this cutting is usually high quality, it is almost always low volume. That low volume means it is more expensive. At the same time, cutting late has three major drawbacks in my book. First of all, it almost always reduces first cutting yield, even though it seldom reduces stand. Second, the growth that we remove isn’t there to stop snow. That snow is an essential piece in next year’s success, whether on irrigated or dryland acres. Finally, that late cutting means our soils change temps more rapidly. That is fine if we get one thaw and then it is spring. But around here, we often get one or two “fake” warmups, and those late cutting acres are more prone to breaking dormancy early.
Finally, on alfalfa, fall is for my money the best time to kill alfalfa. If the forecast is above 50 for a few days, it’s a good time to kill alfalfa. We have to have growth on alfalfa to kill it, and in the spring waiting for that growth often delays the planting date. Also, that green alfalfa in the spring may be a good host for some bugs that can hurt an emerging corn crop, vs. having it killed off in the fall and never providing it as a host for bugs. Finally, and perhaps the biggest reason why the fall killing of alfalfa is the superior program is Nitrogen management. We know that the decomposition of residue requires Nitrogen to feed the microbes that eat the carbon. Starting the process earlier means less tie up of Nitrogen late in the spring as we are establishing yield on the 2019 crop.
So, pick up the phone and send your trusted advisor a text or even give them a call and ask about what we should be doing in October and even into November to manage our acres that have alfalfa on them now, or are going into soybeans. Some smart management right now can not only save us big money in herbicide and tillage for the next crop, but can also set us up for better profits that come from improved weed control, faster growth, and healthier crops next season.
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