ISSUE #530

530 - What Can We Learn?


The 2009 growing season presented numerous challenges to growers striving for high yield and quality. Final harvest statistics show a 22 ton crop with less than 17% sugar and a very low 1.1 SLM. In spite of a difficult year tons per acre will be the 5th or 6th best in company history. However success today is now measured against the three best crops ever grown from 2006-2008. Challenges to 2009 success actually began in the fall of 2008 with near record rainfall saturating the soil profile. Last winter had above average snowfall and was followed by more heavy spring rains. May through August temperatures were below normal, then followed by a very warm September and record cold temperatures in October. Several successful production practices helped minimize impact of adverse environmental conditions in 2009.

What Went Right in 2009?

  • Weed control was excellent across the RRV with both conventional and Roundup Ready® varieties.
  • Plant populations were good to excellent.
  • Variety selection choices for disease management were good for most fields.
  • SLM was excellent at nearly all piling sites.

Let's look at adverse weather and soil conditions and their affect on the 2009 crop.

Problem 1. Very heavy fall rains in September, October and November of 2008.
Effect: Growers were unable to prepare ideal seedbeds and fertilizer application was often delayed until spring. Wet soils may have caused denitrification losses of available N.

Problem 2. Heavy winter snowfall and normal or above spring rainfall.
Effect: The two week or greater delay in planting reduced yields by 2-3 tons. This caused a sugar content decline as well due to a shortened growing season.

Problem 3. Cool growing conditions in May, June and July.
Effect: Crop canopy development and row closure lagged far behind normal with limited leaf area to utilize solar radiation during the long days of May, June and early July.


Problem 4. May through August GDD's were far below the long term average.
Effect: A 350-400 GDD reduction will cause a 1-2 ton yield reduction. Cool conditions may have reduced mineralization and release of N from organic matter for this period too.

Problem 5. Wet soil conditions across much of the RRV after planting.
Effect: It appeared saturated soils caused sprangling that prevents roots from reaching yield potential even if growing conditions improve. Soil tare increases as well. Available N may again have been lost due to denitrification.


Problem 6. Far above average day time highs and night time low temperatures in September.
Effect: Warm days and adequate rainfall spurred crop growth. Wet conditions and very high nighttime temperatures reduced sugar percent increases normally seen in September. These conditions stimulated above average September N mineralization reducing expected sugar percentage increases. Yellowed off fields greened up with more N mineralization and rewetting of surface soil further inhibiting crop quality improvement.

Problem 7. Record cold temperatures and heavy rainfall in October.
Effect: Crop canopy was damaged by repeated frosts and could not support yield and quality improvement. Wet conditions remained unfavorable for sugar content improvement. Fungicides, especially headline, reduced frost damage. Harvest losses also increase.


Other Observations From 2009

  • Leaf architecture, growth habit and canopy development of new diploid varieties may have been affected more than expected by a cool growing season.
  • Review of NDSU and UM fertility research indicates spring N fertilization sometimes results in lower yields.
  • Fields receiving fungicide applications had better canopy development and frost tolerance than without applied fungicide. Especially if two fungicides were applied.
  • Many fields developed some late season powdery mildew especially where no fungicide was applied. This may have impacted final sugar percent in some fields.
  • Rhizoctonia was severe enough in some fields to significantly reduce yield and quality.
  • Conventional varieties tended to have higher sugar content than Roundup Ready® varieties especially in the Crookston district with about 50% each type of variety.