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Don’t Delay Wheat Harvest (Well…If the weather cooperates)

Don’t Delay Wheat Harvest (Well…If the weather cooperates)
By Laura Lindsey
 
Wheat harvest date impacts both grain yield and quality. Delaying wheat harvest puts the crop at risk for increased disease, vomitoxin contamination, lodging, sprouting, and harvest loss.
 
With funding from the Ohio Small Grains Marketing Program, we conducted wheat harvest date trials for three years. However, none of the years were similar to what we are experiencing this year.
 
The biggest impact on wheat grain yield and quality seems to occur when the dry grain is re-wetted in the field prior to harvest. In 2016 in Clark Co., we evaluated wheat harvested on June 29 (at 12% moisture content) and July 8 (at 14% moisture content). Grain moisture increased between June 29 and July 8 due to 0.58” rain between the two dates. When the wheat harvest was delayed until July 8, yield decreased by 9 bu./acre, test weight decreased by 2.9 lb./bu., and vomitoxin level increased by 0.86 ppm. Using a grain price of $4.50/bu. and discounts from a local elevator, the difference the delayed wheat harvest resulted in a loss of $87/acre compared to the June 29 harvest.
 
 
harvested wheat at high moisture (20-30%) and at 13% moisture. The wheat received rainfall between the two harvest dates, but the dry grain was not re-wet (unlike our 2016 study). Pre-harvest sprout, Fusarium-damaged kernels (FDK), and vomitoxin were not influenced by harvest date. Again, this was partly because field-dried grain was not re-wet by precipitation, plus the overall level of scab was very low (< 1, on average). Harvesting around 20% moisture and drying the grain resulted in similar profit as harvesting grain at 13% moisture. However, harvesting at >23% moisture reduced profitability mostly due to costs associated with drying and reduced test weight.
 
So, if you do see higher levels of scab in your field this year than we saw during our study, you will likely benefit from harvesting the grain early (18 to 20% moisture) and then drying it down. As mentioned above, leaving it in the field to dry-down increases the risk of re-wetting, which could increase vomitoxin contamination. Coupled with early harvest, you should increase the fan speed of your combine harvester to blow out scabby, lightweight grain. Our research showed that 5-10% of scab can be managed during harvest – increasing the fan speed will reduce FDK and vomitoxin and increase the test weight of the grain lot, all of which will lead to better overall grain quality, and consequently, lower price discounts.     
 
Wheat harvest date impacts both grain yield and quality. Delaying wheat harvest puts the crop at risk for increased disease, vomitoxin contamination, lodging, sprouting, and harvest loss.