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C.O.R.N
Newsletter
2005-34
October 10, 2005 -
October 18, 2005
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Effects of Harvest Delays on Yield, Grain Moisture and Stalk Lodging in Corn
by
Peter Thomison
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The growing conditions we experienced this past summer, including drought in many areas, have resulted in major stalk lodging problems across Ohio. As corn harvest finally gets under way in earnest, severe lodging is being reported - in some cases, corn has been nearly flattened by recent storms. The good news is that the warm, dry weather this fall has been very favorable for grain drying, and many fields, even mid-May replant fields, have corn with grain moisture levels below 20%. Therefore there is little need to field dry corn further given these low moisture levels.
Harvest delays expose the crop to less favorable weather conditions, as well as wildlife damage. Additional losses may occur when ears on lodged plants come in contact with wet soils and surface residues resulting in development of ear rots. Ear rots reduce grain quality and lead to significant dockage when the grain is marketed. Some ear rots produce mycotoxins, which may cause major health problems if fed to livestock.
We recently completed a study that evaluated effects of plant population (24,000, 30,000, 36,000, and 42,000 plants/A) and harvest dates (early-mid Oct., Nov. and Dec.) on the agronomic performance of four hybrids differing in maturity and stalk quality. The research was supported by a Pioneer Crop Management Award and the Ohio Top Farmers. Although the four hybrids exhibited similar yield potential when harvested early (early/mid Oct.), differences in yield became evident with harvest delays, which could be attributed to differences in stalk quality. Yield differences among plant population were generally small on the first harvest date, but with harvest delays, major yield losses occurred at the higher plant populations, especially 42,000 plants/A, due to increased stalk lodging. After the first harvest in early/mid October, stalk lodging increased as much as 80% - resulting in yield losses of nearly 50% for certain hybrids. Most of the yield loss occurred following the second harvest date in early November. Grain moisture, averaged about 24% on the first harvest date, 18% on the second harvest, and 17% on third harvest date.
Changes in grain moisture with harvest delays.
Grain moisture content showed a decrease from early-mid Oct. to early-mid Nov. but little or no change between early-mid Nov. and early-mid Dec. (Table 1). Grain moisture, averaged across locations, years, hybrids, and plant populations, decreased 6.3% points between early-mid Oct. and early-mid Dec., with most of the decrease occurring between early-mid Oct. and early-mid Nov. (5.8 % points); only a 0.5 % point decrease occurred after early-mid November. At five of the eight test locations, grain moisture content in early-mid Nov., averaged less than 18% points. At the other three sites, grain moisture levels in early-mid Nov. ranged from 20 to 21% points. Population effects on grain moisture content were not consistent. Differences in grain moisture were also evident among hybrids in early-mid Oct. but generally negligible on the later dates.
Table 1. Grain Moisture (%)
Plant Population
| HD1
| HD2
| HD3
| 24,000
| 24.9
| 18.2
| 17.4
| 30,000
| 24.0
| 17.9
| 17.3
| 36,000
| 22.4
| 18.0
| 17.6
| 42,000
| 23.7
| 17.9
| 17.7
| Average
| 23.8
| 18.0
| 17.5
|
HD1 = early/mid-Oct., HD2 = early/mid-Nov., HD3 = on or after mid-Dec.
Changes in stalk quality with harvest delays.
Harvest delays resulted in greater stalk rot and lodging (Tables 2 and 3). The greatest increase in stalk rot occurred between early/mid-Oct and early/mid-Nov, whereas most of the increase in stalk lodging occurred after early/mid-Nov. Averaged across locations, years, populations and hybrids, stalk rot increased from 44% in early/mid-Oct to 83% in early/mid-Nov and 91% in/or after mid-Dec.; stalk lodging increased from 4% in early/mid-Oct to 24% in early/mid-Nov and 47% in/or after mid-Dec.
The major reduction in grain yield associated with harvest delay can be attributed to the increase in stalk lodging between the early/mid-Nov and mid-Dec harvest dates.
Table 2. Stalk Rot (%)
Plant Population
| HD1
| HD2
| HD3
| 24,000
| 21
| 72
| 83
| 30,000
| 42
| 80
| 89
| 36,000
| 53
| 87
| 95
| 42,000
| 58
| 93
| 96
| Average
| 43
| 83
| 90
|
HD1 = early/mid-Oct., HD2 = early/mid-Nov., HD3 = on or after mid-Dec.
Table 3. Stalk Lodging (%)
Plant Population
| HD1
| HD2
| HD3
| 24,000
| 3
| 17
| 33
| 30,000
| 4
| 20
| 41
| 36,000
| 4
| 27
| 52
| 42,000
| 4
| 33
| 59
| Average
| 4
| 24
| 46
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HD1 = early/mid-Oct., HD2 = early/mid-Nov., HD3 = on or after mid-Dec.
The 2003 and 2004 growing seasons during which most of this research was conducted were extremely favorable for corn growth and yield. Record corn yields were achieved statewide. Due to stress conditions in 2005, stalk quality is inferior to that of the past two years. In some severely stressed fields, corn died prematurely in August and September and significant stalk deterioration has already occurred. Given the poor quality of corn stalks in many corn fields in 2005, it’s likely that we could expect greater stalk lodging with shorter harvest delays than the research above would indicate.
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