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Proper sorghum harvest timing essential

Drought, flood and hail, plus a handful of other pestilences have hammered Southwestern grain sorghum farmers already this growing season, leaving many scratching their heads and wondering what else can happen to lower already low expectations from this crop.

Harvesting at the wrong time comes to mind. Unfortunately, selecting the right balance between moisture content and subsequent dockage and decreased standability at lower moisture levels may be more art than science.

“One of the biggest challenges in sorghum production is maintaining standability,” says John Mick, a district sales manager with Pioneer Hi-Bred, International, in Colby Kan.

Many factors influence a grain sorghums stalk's ability to stay erect until harvested, Mick says. Harvest moisture is one of the most important.

“Most standability concerns develop when growers leave sorghum in the field until grain moisture is below 14 percent. Harvesting at 16 percent moisture or more prevents a significant amount of standability problems.” He says.

“But sorghum producers hesitate to cut early because they get docked for excess moisture at the elevator.”

Mick says growers should look hard at the economics. “When you analyze the costs of moisture dockage compared to the costs of lodging (lost grain, reduced grain quality, volunteer problems the following year) a producer usually comes out better harvesting at a higher moisture.”

Mick offers a checklist for harvest timing.

  • Lodging

    Lodging is relatively easy to spot before it happens and is associated with fusarium and charcoal stalk rots. Both diseases show symptoms in the field prior to lodging taking place. Symptoms of fusarium stalk rot include reddish discoloration inside the stalk, premature plant death, and small berry size.

    Charcoal stalk rot symptoms include shredded pith tissue and a multitude of small black spots inside the stalk. When these symptoms are evident, farmers should consider early harvest to prevent stalk rots.

  • Weed invasion

    Shattercane, johnsongrass and incursion by other sorghum may create a persistent problem. The threat is greater when neighboring fields contain high amounts of shattercane, Johnsongrass, and other sorghum forages, such as sudangrass (not sorghum-sudangrass crosses).

    These sorghums will cross-pollinate with grain sorghum, producing hybrid off-types that can survive over winter and come back the next growing season. Farmers should pay attention to the location and density of these sorghums near their fields at harvest to get an idea of the threat potential.

  • Combine settings

    Sorghum producers should always pay attention to combine cylinder and fan settings. Sorghum is notorious for producing highly variable kernel sizes, so a poorly adjusted combine cylinder will cause excessive damage to the grain. When fan speeds are too high, growers can expect excessive loss of light kernels.

  • Hybrids

    One of the most important decisions a sorghum producer makes annually is hybrid selection. A grower should never make hybrid comparisons from the combine without an accurate yield measurement.

Hybrid differences in moisture, test weight, and head type (open vs. closed) will confound visual comparisons of hybrid performance. The only accurate measure at harvest is a side-by-side comparison weighed with an accurate scale.

Test weight is the great equalizer. It is routine to find test weight difference of four to six pounds among hybrids. Judging hybrids from the combine at harvest, based on visual observation, is one of the costliest mistakes sorghum producers make.

Bracken Finney, Pioneer field agronomist at Taylor, Texas, estimates sorghum harvest in south Texas was 20 percent complete, by mid-July. Early July rains, he says, kept farmers out of the fields until July 8.

They were able to get back in on Monday. Areas in south Texas received between 4.5 to 31 inches of rain. Rains affect both test weights and quality.

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