Beet the Heat When Topping Sugarbeets

Published in the November 2012 Issue Published online: Nov 06, 2012 Steven Poindexter, Senior Sugarbeet Extension Educ
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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 degrees' 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 those that are defoliated. This trial was conducted during early-season delivery on a bright and sunny Oct. 4, 2011. Sugarbeets were defoliated at 10:45 a.m. at 57 degrees air temperature and again at 1:30 p.m. with air temperature at 72 degrees. Defoliated beets were compared to sugarbeets with full canopies in the adjacent rows. Temperature was taken every 15 minutes with a digital thermometer inserted two inches into the beet crowns.

Sugarbeets that were not defoliated (full canopy) gained temperature slower than those that were defoliated. Defoliated beets actually increased temperature more quickly than the surrounding air temperature. (See Chart on page 28) This indicates that the radiant energy from the 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 degrees warmer than the non-defoliated beets. Defoliated beets gained about 5 degrees per hour in temperature. The rate of warming for full-canopy beets was 2.4 degrees per hour, or half that of defoliated.

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 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. The benefit of this approach would be the improved quality of harvested beets due to better defoliation. This could easily pay good dividends to cover the wage of the topper operator and improve beet storability and profitability of the cooperatives.