Start Strong, Finish Strong

Published online: Jan 17, 2024 Feature Clarke Alder, Agronomist, Weed Science, Amalgamated Sugar Company
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Farming is full of management decisions.

On the daily, growers are faced with a barrage of choices from, “When can I get over to check on the peas today?” or “Who’s going to teach the new guy the right way to mix a backpack sprayer?” to “Am I going to try a new fall tillage this year on Dad’s Place?” or “Should I try this new tankmix on my beets?”

Some of the answers to those daily questions don’t come easy and others are fairly cut and dry. Experience dictates and history shows that a decision made ahead of time is a decision one no longer has to make. When it comes to managing a crop – and especially weeds within that crop, it is much better to have a plan in place than to make it up on the fly.  

Over the past couple of years society (growers included) has experienced what some would deem extreme inflation. Although it is not the worst our country has seen in history, heavy effects are still being felt as margins tighten and budgets are disrupted in nearly every industry. Couple that with the difficulties the western U.S. has had with Mother Nature and many growers have had to make choices they’ve not made in a very long time - or maybe even ever. As some may be faced with having to chose between things such as fertilizer vs. insecticides, or water vs. weed control, the following will hopefully provide a case for starting strong and following through with full season weed control to maximize profitability in a sugarbeet crop.

When it comes to establishing a beet crop, there are many things at play – things like seed-to-soil contact, soil temperature, soil moisture and others. One that is often overlooked but every bit as important to the establishment of a healthy crop is weed control. As seedlings, sugarbeets are very susceptible to competition from other plants.

Research has shown that sugarbeets have the ability to “detect” whether other green plants are present within the immediate vicinity. Research has also shown that to maximize yield in sugarbeets, the crop needs to be kept weed-free for at least the first eight weeks after planting. The time between emergence and row closure is the most critical time for growers to focus on controlling weeds as the amount of bare ground or “opportunity” for weed establishment is highest.

Studies have also demonstrated that only a small number of kochia, lambsquarters or pigweed plants, (about 4 plants per 100 square feet) are needed to significantly decrease the yield of a sugarbeet crop. Four plants per 100 square feet can mean the difference between a 45-ton beet crop and a 36-ton beet crop, or around $550/A with last year’s (2022) prices.

Several years ago, research was done by Amalgamated Sugar on the economics of skipping an herbicide treatment. The research was based on a standard plan which included a pre-plant burndown treatment (providing a clean seedbed for planting) plus three applications of Roundup Powermax throughout the season.

Several additional herbicide plans were compared, each one receiving one less treatment than the previous treatment to study the effects of the remaining weed population on the final yield and sugar content of the beet crop. Once yield was realized, the dollars spent for each application were tallied and compared to the dollars a grower would have brought in from the crop receiving the respective herbicide treatments. The study concluded several key things. These are also illustrated in the graphs in the sidebar.

Planting into a clean seedbed is highly crucial, especially if extenuating circumstances during the early season may prevent another treatment from being made until much later (i.e. 8-10 leaf). Whether a clean seedbed is achieved chemically or mechanically doesn’t matter as much as the actual absence of weeds when the beets are planted.  Avoiding weed competition from the very beginning of the crop’s establishment will provide a very positive impact.

Treatments between the 2-leaf and 8-leaf stages are critical for maximizing yield and profitability of the beet crop.  In the study, it was estimated that a grower’s loss in yield constituted a $247-288 per acre potential loss if one treatment (at 2-leaf) was skipped, and a $295-587 loss if more (2-leaf and 8-leaf) were skipped.  The results were exaggerated when the beets were not planted into a clean seedbed. 

The amount of yield lost due to skipping just one treatment between planting and row closure was nearly triple the cost of the application itself.  If the cost to apply Roundup® Powermax one time was $80 per acre in 2022, then the yield loss in dollars per acre resulting from a skipped treatment was far greater than any realized savings from not making an early-season trip through the field.  Couple that with missed opportunities to control other pests such as root maggot flies, leafminer, or army and webworms with a tankmix, the yield losses could be even greater.  

When it comes to making decisions and having one’s mind made up ahead of time, there are some choices that simply pay to not have to think about.  Weeds are a very real threat to all crops and are never going away.  Making timely applications throughout the entire season will continue to be increasingly crucial as more resistant weeds make their way into our crops.  The parting advice - Be vigilant, be proactive, and finish strong.

Sidebar

In the study, two full-season checks were included which contained glyphosate treatments at 2-leaf, 8-leaf, and canopy closure of the beets. One check also contained a pre-plant application to clean up the field prior to planting.

The two checks yielded similarly because full-season weed control was achieved at the correct early-season timings in both cases. Where there were no pre-plant applications made, yield was impacted greater by skipping a post-plant application (such as 2 or 8-leaf) because of a heavier presence of weeds.

Yield differences were even more noticable when translated to dollars per acre. When beets weren't planted into a clean seedbed, the potential for yield loss was far greater as the first application was further delayed into the season.

As the figures indicate, some weed control, even late in the season, is significantly better than none at all, but why take a chance and leave potentially hundreds of dollars per acre in the field?