C. Maturity and Harvest Conditions
Warm weather and drier conditions shortened grain-fill and hastened harvest
When the sorghum plant reaches physiological maturity (or black layer), the grain achieves its final maximum dry mass and nutrient content. Prior to reaching the black layer stage, freezing temperatures could lower test weight (through small seeds), impede final maturity, and consequently reduce yields. Once maturity has been reached and until harvest time, sorghum grain will dry down from about 35% to around 20% moisture. The dry-down rate is influenced by hybrid maturity, grain moisture at the beginning of dry down, and temperature during the dry-down period. If sorghum does not dry down suffciently, the higher-moisture grain remains soft and becomes more susceptible to pericarp breakage as well as more diffcult to thresh.
1. Early Harvest Area
Typically, 80% of the sorghum in the EHA is harvested by the end of August. However, in 2015, similar harvest progress was achieved approximately a week later than normal. Despite delayed planting in this area, drier and warmer weather after mid-pollination hastened maturity and harvest. For this region, freeze is not an issue.
The main production issue in the EHA in 2015 was related to the sugarcane aphid (Melanaphis sacchari), which infested and damaged some of the crop. The infestation of this pest can impact plant health, seed weight, yield, and ultimately grain quality. Since its presence is new in this area, the degree to which it affects yield and quality is still being determined.
2. Late Harvest Area
Close to 80% of the LHA sorghum crop is usually harvested by the beginning of November. Harvest progress in 2015 was comparable to the average for the 2010-2014 period. Despite the 2015 LHA crop’s late start, its comparable harvest progress to the 2010-2014 period was due to the warmer and drier late reproductive weather conditions in 2015. There was also no widespread early freeze that would have slowed maturity and possibly enabled pericarpcracked grain or led to harvest and disease issues.
The wet conditions in the early part of the LHA growing season caused poor root establishment and compaction problems in some areas. In addition, the dry, warm conditions from mid-grain filling to harvest increased nutrient remobilization to the grains and weakened the stalks. The combination of these two sets of conditions increased the susceptibility of the sorghum plants in the LHA to fungal diseases such as charcoal rot and Fusarium stalk rot, and to lodging issues (the leaning or falling over of the plant).
Similar to the EHA, the sugarcane aphid (Melanaphis sacchari) advanced far north and impacted sorghum production, primarily from the mid-vegetative to late reproductive stages, in areas of Oklahoma and Kansas. The presence of aphids in the EHA impacted yields and sorghum grain quality.