Beat the heat when topping sugarbeets

Topping sugarbeets too far ahead of the harvester will lead to warm beets in the pile that will reduce quality and storability.

It has long been known that heat is the enemy when it comes to harvesting and storing sugarbeets. Piled under warm conditions, length of storability is greatly reduced due to increased respiration, microbial activity and regrowth. These factors combined will reduce beet quality and factory efficiency. Under warm conditions, sugarbeet respiration will increase and burn up sugar stored in the root. For every 15-degree increase in beet temperature, respiration will double. Keeping the sugarbeet canopy intact until just prior to lifting goes a long way in beating the heat to keep the roots cool.

In 2011, a study was conducted by Sugarbeet Advancement at the Saginaw Valley Research and Extension farm. The trial was conducted to compare how fast temperature increases in beets that have a canopy compared to defoliated. This trial was conducted during early season delivery on October 4. The day was bright and sunny. Sugarbeets were defoliated at 10:45 a.m. with air temperature at 57 degrees Fahrenheit and 1:30 p.m. with air temperature at 72 F. Defoliated beets were compared to sugarbeets that had full canopies in the adjacent rows. Digital thermometers were inserted 2 inches into the beet crowns and temperature was taken every 15 minutes.

Sugarbeets that were not defoliated (full canopy) gained temperature slower than those that were defoliated. Defoliated beets actually increased temperature more quickly than air temperature (Table 1). This indicates that the radiant energy, or sun, was also warming the crown. By mid- to late afternoon, sugarbeet crowns were actually warmer than the ambient air temperature for both defoliation timings. By mid-afternoon the 10:45 a.m. defoliated beets were 13.5 F warmer than the non-defoliated beets. Defoliated beets gained about 5 F per hour in temperature. The rate of warming for non-defoliated beets was 2.4 F per hour, or half that of defoliated.

Beet and air temperatures

In order to beat the heat, growers are encouraged to not get too far ahead of the harvester. This is particularly critical during permanent pile when the temperature for piling is marginal and the sun is brightly shining. Sugarbeets should not be defoliated more than 30 minutes ahead of harvest. Often, those topping beets will need to stop and wait for the harvester to catch up. Another strategy is to slow down your topper to better match harvester progress. This approach may include the benefit of improved beet quality by better defoliation. This could easily pay good dividends to cover the wage of the topper operator and improve beet storability and profitability of the Cooperative.

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