Effects of Harvest Delays on Corn Hybrid Performance
CROP INSIGHTS University/Pioneer Research1 Update:
Effects of Harvest Delays on Corn Hybrid Performance by Tom Doerge, Agronomy Research Manager Key Findings of CMRA1 Research Project • Delaying corn harvest has become more common as growers attempt to reduce costs. Research on this practice was conducted in the Eastern Corn Belt to determine the effects of harvest delays and plant population on hybrid performance. • Results showed that nearly 90% of the yield loss associated with delayed corn harvest occurred when delays extended beyond mid-November. • Higher plant populations resulted in increased grain yields when harvest occurred in early to mid-October. Only when harvest was delayed until mid-November or later did yields decline at plant populations above 30,000/acre. • Hybrids with lower stalk strength ratings exhibited greater stalk rot, lodging and yield loss when harvest was delayed. Early harvest of these hybrids eliminated this effect. • The greatest increase in stalk rot incidence came between harvest dates in October and November. In contrast, stalk lodging increased most after November. • In this study, harvest delays had little or no effect on grain quality characteristics such as oil, protein, starch, kernel breakage or mycotoxin content. • Delaying harvest until November decreased grain moisture content by 5.8% (from 23.8 to 18.0%). Further harvest delays achieved almost no additional grain drying.
Introduction Corn harvest delays have become more common in recent years as producers strive to reduce equipment and energy costs. As growers manage more cropland, spreading the same equipment costs over those acres reduces production costs per acre. Rapidly increasing energy costs are also encouraging growers to employ delayed harvest as a strategy to reduce at-harvest grain moisture levels and the associated drying costs. However, delayed harvest also increases risk of yield and quality losses. Stalk lodging, ear rot development, weathering and even wildlife damage can all negatively impact a crop left too long in the field. Finding the balance between cost reduction and risk of yield and quality losses is a frequent dilemma for farmers, and the subject of a recent research study reported in this Crop Insights.
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VOL. 15 • NO. 12 • PAGE
Timely harvest reduces risk of yield and quality losses due to stalk and ear rots, weathering and wildlife damage.
Stalk and Ear Rot Occurrence A major concern with delayed corn harvest is the adverse effect on stalk quality. This is an issue for all growers but especially for those in the more humid Eastern Corn Belt. In Ohio for example, stalk rots are the most common disease problem of corn and can lead to stalk lodging. When harvest is delayed, the impact of stalk rots on lodging is magnified, slowing the harvest operation and reducing yield and quality. Various cultural practices such as plant population, fertility rates and reduced tillage can also influence stalk quality and increase lodging when harvest is delayed. Corn growers are using higher seeding rates, which can create more stress on individual plants, especially if soil moisture and nutrients are limiting. Reduced use of fertilizers (especially potassium) to cut input costs will also increase the potential for stalk quality problems (Doerge, 2005). Reduced tillage and greater surface residues can increase the severity of stalk rot and leaf diseases. Leaf diseases such as gray leaf spot, Stewart’s bacterial blight and northern corn leaf blight can also predispose corn to stalk quality problems and increased lodging with late harvest. Another concern with delayed harvest is risk of increased ear rot problems. Ear rots may develop on standing corn or on
1
®Registered trademark of Pioneer Hi-Bred International, Inc. ©2005, PHII
lodged plants as ears contact the ground. In either case, delayed harvest allows ear rot problems to worsen, especially if wet conditions develop in the fall. Ear rots reduce grain yield and quality and lead to significant dockage when the grain is marketed. Some ear rots produce mycotoxins, which may cause health problems if fed to livestock.
Research Objective Past research has indicated that the optimal grain moisture content for minimizing harvest losses is about 25%. However, many growers wait until grain moisture content falls below 20% before harvesting, which may subject a crop to significant weathering. In some growing seasons, persistent rains during October and November prevent timely harvests and increase the likelihood for in-field losses.
Study Description Field experiments were established in 2002-2004 at three sites in Ohio - South Charleston, Hoytville and Wooster. The experimental treatments at each location were replicated three times in a randomized complete block arranged in a split-plot layout. Hybrids were the main plots and plant populations the subplots. Four hybrids were evaluated. Stalk strength scores were below average for Pioneer® brand 34B23 and 34M94 and above average for Pioneer 33J56 and 33G26 corn hybrids. Four plant populations were established by overplanting and thinning back to 24,000, 30,000, 36,000 and 42,000 plants/acre. Plots consisted of four 30-inch rows approximately 25 feet in length. Plots were combine harvested three times per season during these target periods: early October (Date 1), early November (Date 2), and early December (Date 3). At Wooster the third harvest was delayed until March 22, 2005 due to persistent wet soil conditions. Data were collected for grain yield, harvest moisture of grain, and stalk and root lodging. Grain samples were analyzed for oil, protein and starch composition and kernel breakage. Stalk deterioration was assessed by several methods, including squeezing the first above-ground internode by hand, using an electronic rind penetrometer and inspecting visually. Samples of stalk tissue were also collected from selected treatments and locations to determine the presence and identity of fungal pathogens.
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VOL. 15 • NO. 12 • PAGE
Stalk quality was determined by squeezing the stalk by hand (L), by using a rind penetrometer (R) and by visual inspection. Images courtesy of Peter Thomison, Ohio State University.
Results Did harvest delays affect yield? Yes. Yields averaged across all sites, years, populations and hybrids decreased about 13% between Date 1 and Date 3. However, yield loss between Date 1 and Date 2 was small, about 2%. Most of the yield loss, about 11%, occurred following the November harvest date. Yield losses between the first and last harvest dates ranged from a low of 5% to a high of 24%. Did plant population affect yield response to late harvest? Yes, and the effects of population on yield were greater on Date 2 than on Date 3. Yield losses caused by harvest delays were greater at the two higher plant populations (Figure 1). 210
Grain Yield (bu/acre)
A better understanding of hybrid response to weathering conditions, especially with regard to stalk and grain quality, would help corn growers manage hybrids more effectively in the varying crop production environments of the Eastern Corn Belt. For this reason, a study on corn harvest delays was conducted by Dr. Peter Thomison of the Ohio State University. The primary objective of this study was to determine the effects of harvest delays, plant population and hybrid characteristics on stalk disease incidence, stalk lodging and ultimately grain yield and quality
200
194
196 197
194 193
194
191
190
188 191
187
180
24,000 ppa 30,000 ppa 36,000 ppa 42,000 ppa Average
173 174 161 168
170
167
160 150
Harvest Date 1
Harvest Date 2
Harvest Date 3
Figure 1. Effect of plant population and harvest date on grain yield. Averaged across 4 hybrids and 8 site years, 2002 to 2004. Date 1 = early/mid Oct. Date 2 = early/mid Nov. Date 3 = after mid-Dec.
2
®Registered trademark of Pioneer Hi-Bred International, Inc. ©2005, PHII
Between Date 1 and Date 3, yields decreased about 10% at 24,000 and 30,000 plants/acre, whereas at 36,000 and 42,000 plants/acre, yields decreased about 15 and 18%, respectively.
Was yield response to harvest date affected by hybrid? Yes, but typically not until after the first harvest date. After Date 1, the response of individual hybrids to harvest date was directly related to the stalk strength rating of the hybrid. Hybrids with below-average stalk scores suffered nearly double the yield loss between Date 2 and Date 3 compared to hybrids with above average stalk scores. In addition, hybrids with lower stalk scores were more prone to greater reduction in yield at the two highest populations. For example, at 42,000 plants/acre, the yield loss associated with the delayed harvest of Pioneer hybrid 33J56, averaged across locations, was 22%, whereas the yield loss of Pioneer hybrid 33G26 was generally negligible. Did harvest delays affect stalk quality ? As expected, harvest delays resulted in greater stalk rot and lodging. The greatest increase in stalk rot occurred between Date 1 and Date 2, whereas most of the increase in stalk lodging occurred after Date 2. Averaged across sites, years, populations and hybrids, stalk rot increased from 43% on Date 1 to 83% on Date 2 and 90% on Date 3 (Figure 2). Stalk lodging increased from 4% on Date 1 to 24% on Date 2 and 46% on Date 3 (Figure 3). The major reduction in grain yield associated with harvest delay was attributed to the increase in stalk lodging between Date 2 and Date 3. 24,000 ppa 30,000 ppa 36,000 ppa 42,000 ppa Average
100
% Stalk Rot
80
95
93 80
83
90
72
53 42
43
40 21
20 0
Harvest Date 1
Harvest Date 2
Harvest Date 3
Figure 2. Effect of plant population and harvest date on % stalk rot. Averaged across 4 hybrids and 8 site years, 2002 to 2004. Date 1 = early/mid Oct. Date 2 = early/mid Nov. Date 3 = after mid-Dec.
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46 41 33
33
30
27
24
20
20
17
10 3
0
4
4
4
Harvest Date 1
4
Harvest Date 2
Harvest Date 3
Figure 3. Effect of plant pop. and harvest date on % stalk lodging. Averaged across 4 hybrids and 8 site years, 2002 to 2004. Date 1 = early/mid Oct. Date 2 = early/mid Nov. Date 3 = after mid-Dec.
With harvest delays, did plant population and hybrid affect changes in stalk quality? Yes, stalk rot and lodging increased at the higher plant populations, and this effect was magnified by late harvesting. Differences in stalk rot incidence across the plant population treatments were most pronounced at Date 1, whereas differences for stalk lodging were greatest at Date 3. Again, stalk rot and lodging were greater for hybrids with the lower stalk strength ratings. Differences in stalk strength based on rind penetrometer measurements were not consistent across the different harvest dates, hybrids or plant population treatments.
No consistent increase in major stalk rot fungal pathogens was evident following the first harvest date. Fusarium graminearum was the principle fungus isolated from stalks and the incidence of stalks infected ranged from 13% to 73%. Other Fusarium spp. (F. moniliforme, F. semitectum and F. equseti) were present in 3 to 17% of the stalks.
83
58
60
40
52
Did harvest delays, hybrid and plant population influence infection of corn by stalk rot fungal pathogens?
96
89
87
24,000 ppa 30,000 ppa 36,000 ppa 42,000 ppa Average
50
% Stalk Lodged
Between Date 1 and Date 2, little yield loss (
Effects of Harvest Delays on Corn Hybrid Performance by Tom Doerge, Agronomy Research Manager Key Findings of CMRA1 Research Project • Delaying corn harvest has become more common as growers attempt to reduce costs. Research on this practice was conducted in the Eastern Corn Belt to determine the effects of harvest delays and plant population on hybrid performance. • Results showed that nearly 90% of the yield loss associated with delayed corn harvest occurred when delays extended beyond mid-November. • Higher plant populations resulted in increased grain yields when harvest occurred in early to mid-October. Only when harvest was delayed until mid-November or later did yields decline at plant populations above 30,000/acre. • Hybrids with lower stalk strength ratings exhibited greater stalk rot, lodging and yield loss when harvest was delayed. Early harvest of these hybrids eliminated this effect. • The greatest increase in stalk rot incidence came between harvest dates in October and November. In contrast, stalk lodging increased most after November. • In this study, harvest delays had little or no effect on grain quality characteristics such as oil, protein, starch, kernel breakage or mycotoxin content. • Delaying harvest until November decreased grain moisture content by 5.8% (from 23.8 to 18.0%). Further harvest delays achieved almost no additional grain drying.
Introduction Corn harvest delays have become more common in recent years as producers strive to reduce equipment and energy costs. As growers manage more cropland, spreading the same equipment costs over those acres reduces production costs per acre. Rapidly increasing energy costs are also encouraging growers to employ delayed harvest as a strategy to reduce at-harvest grain moisture levels and the associated drying costs. However, delayed harvest also increases risk of yield and quality losses. Stalk lodging, ear rot development, weathering and even wildlife damage can all negatively impact a crop left too long in the field. Finding the balance between cost reduction and risk of yield and quality losses is a frequent dilemma for farmers, and the subject of a recent research study reported in this Crop Insights.
CROP INSIGHTS
•
VOL. 15 • NO. 12 • PAGE
Timely harvest reduces risk of yield and quality losses due to stalk and ear rots, weathering and wildlife damage.
Stalk and Ear Rot Occurrence A major concern with delayed corn harvest is the adverse effect on stalk quality. This is an issue for all growers but especially for those in the more humid Eastern Corn Belt. In Ohio for example, stalk rots are the most common disease problem of corn and can lead to stalk lodging. When harvest is delayed, the impact of stalk rots on lodging is magnified, slowing the harvest operation and reducing yield and quality. Various cultural practices such as plant population, fertility rates and reduced tillage can also influence stalk quality and increase lodging when harvest is delayed. Corn growers are using higher seeding rates, which can create more stress on individual plants, especially if soil moisture and nutrients are limiting. Reduced use of fertilizers (especially potassium) to cut input costs will also increase the potential for stalk quality problems (Doerge, 2005). Reduced tillage and greater surface residues can increase the severity of stalk rot and leaf diseases. Leaf diseases such as gray leaf spot, Stewart’s bacterial blight and northern corn leaf blight can also predispose corn to stalk quality problems and increased lodging with late harvest. Another concern with delayed harvest is risk of increased ear rot problems. Ear rots may develop on standing corn or on
1
®Registered trademark of Pioneer Hi-Bred International, Inc. ©2005, PHII
lodged plants as ears contact the ground. In either case, delayed harvest allows ear rot problems to worsen, especially if wet conditions develop in the fall. Ear rots reduce grain yield and quality and lead to significant dockage when the grain is marketed. Some ear rots produce mycotoxins, which may cause health problems if fed to livestock.
Research Objective Past research has indicated that the optimal grain moisture content for minimizing harvest losses is about 25%. However, many growers wait until grain moisture content falls below 20% before harvesting, which may subject a crop to significant weathering. In some growing seasons, persistent rains during October and November prevent timely harvests and increase the likelihood for in-field losses.
Study Description Field experiments were established in 2002-2004 at three sites in Ohio - South Charleston, Hoytville and Wooster. The experimental treatments at each location were replicated three times in a randomized complete block arranged in a split-plot layout. Hybrids were the main plots and plant populations the subplots. Four hybrids were evaluated. Stalk strength scores were below average for Pioneer® brand 34B23 and 34M94 and above average for Pioneer 33J56 and 33G26 corn hybrids. Four plant populations were established by overplanting and thinning back to 24,000, 30,000, 36,000 and 42,000 plants/acre. Plots consisted of four 30-inch rows approximately 25 feet in length. Plots were combine harvested three times per season during these target periods: early October (Date 1), early November (Date 2), and early December (Date 3). At Wooster the third harvest was delayed until March 22, 2005 due to persistent wet soil conditions. Data were collected for grain yield, harvest moisture of grain, and stalk and root lodging. Grain samples were analyzed for oil, protein and starch composition and kernel breakage. Stalk deterioration was assessed by several methods, including squeezing the first above-ground internode by hand, using an electronic rind penetrometer and inspecting visually. Samples of stalk tissue were also collected from selected treatments and locations to determine the presence and identity of fungal pathogens.
CROP INSIGHTS
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VOL. 15 • NO. 12 • PAGE
Stalk quality was determined by squeezing the stalk by hand (L), by using a rind penetrometer (R) and by visual inspection. Images courtesy of Peter Thomison, Ohio State University.
Results Did harvest delays affect yield? Yes. Yields averaged across all sites, years, populations and hybrids decreased about 13% between Date 1 and Date 3. However, yield loss between Date 1 and Date 2 was small, about 2%. Most of the yield loss, about 11%, occurred following the November harvest date. Yield losses between the first and last harvest dates ranged from a low of 5% to a high of 24%. Did plant population affect yield response to late harvest? Yes, and the effects of population on yield were greater on Date 2 than on Date 3. Yield losses caused by harvest delays were greater at the two higher plant populations (Figure 1). 210
Grain Yield (bu/acre)
A better understanding of hybrid response to weathering conditions, especially with regard to stalk and grain quality, would help corn growers manage hybrids more effectively in the varying crop production environments of the Eastern Corn Belt. For this reason, a study on corn harvest delays was conducted by Dr. Peter Thomison of the Ohio State University. The primary objective of this study was to determine the effects of harvest delays, plant population and hybrid characteristics on stalk disease incidence, stalk lodging and ultimately grain yield and quality
200
194
196 197
194 193
194
191
190
188 191
187
180
24,000 ppa 30,000 ppa 36,000 ppa 42,000 ppa Average
173 174 161 168
170
167
160 150
Harvest Date 1
Harvest Date 2
Harvest Date 3
Figure 1. Effect of plant population and harvest date on grain yield. Averaged across 4 hybrids and 8 site years, 2002 to 2004. Date 1 = early/mid Oct. Date 2 = early/mid Nov. Date 3 = after mid-Dec.
2
®Registered trademark of Pioneer Hi-Bred International, Inc. ©2005, PHII
Between Date 1 and Date 3, yields decreased about 10% at 24,000 and 30,000 plants/acre, whereas at 36,000 and 42,000 plants/acre, yields decreased about 15 and 18%, respectively.
Was yield response to harvest date affected by hybrid? Yes, but typically not until after the first harvest date. After Date 1, the response of individual hybrids to harvest date was directly related to the stalk strength rating of the hybrid. Hybrids with below-average stalk scores suffered nearly double the yield loss between Date 2 and Date 3 compared to hybrids with above average stalk scores. In addition, hybrids with lower stalk scores were more prone to greater reduction in yield at the two highest populations. For example, at 42,000 plants/acre, the yield loss associated with the delayed harvest of Pioneer hybrid 33J56, averaged across locations, was 22%, whereas the yield loss of Pioneer hybrid 33G26 was generally negligible. Did harvest delays affect stalk quality ? As expected, harvest delays resulted in greater stalk rot and lodging. The greatest increase in stalk rot occurred between Date 1 and Date 2, whereas most of the increase in stalk lodging occurred after Date 2. Averaged across sites, years, populations and hybrids, stalk rot increased from 43% on Date 1 to 83% on Date 2 and 90% on Date 3 (Figure 2). Stalk lodging increased from 4% on Date 1 to 24% on Date 2 and 46% on Date 3 (Figure 3). The major reduction in grain yield associated with harvest delay was attributed to the increase in stalk lodging between Date 2 and Date 3. 24,000 ppa 30,000 ppa 36,000 ppa 42,000 ppa Average
100
% Stalk Rot
80
95
93 80
83
90
72
53 42
43
40 21
20 0
Harvest Date 1
Harvest Date 2
Harvest Date 3
Figure 2. Effect of plant population and harvest date on % stalk rot. Averaged across 4 hybrids and 8 site years, 2002 to 2004. Date 1 = early/mid Oct. Date 2 = early/mid Nov. Date 3 = after mid-Dec.
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VOL. 15 • NO. 12 • PAGE
46 41 33
33
30
27
24
20
20
17
10 3
0
4
4
4
Harvest Date 1
4
Harvest Date 2
Harvest Date 3
Figure 3. Effect of plant pop. and harvest date on % stalk lodging. Averaged across 4 hybrids and 8 site years, 2002 to 2004. Date 1 = early/mid Oct. Date 2 = early/mid Nov. Date 3 = after mid-Dec.
With harvest delays, did plant population and hybrid affect changes in stalk quality? Yes, stalk rot and lodging increased at the higher plant populations, and this effect was magnified by late harvesting. Differences in stalk rot incidence across the plant population treatments were most pronounced at Date 1, whereas differences for stalk lodging were greatest at Date 3. Again, stalk rot and lodging were greater for hybrids with the lower stalk strength ratings. Differences in stalk strength based on rind penetrometer measurements were not consistent across the different harvest dates, hybrids or plant population treatments.
No consistent increase in major stalk rot fungal pathogens was evident following the first harvest date. Fusarium graminearum was the principle fungus isolated from stalks and the incidence of stalks infected ranged from 13% to 73%. Other Fusarium spp. (F. moniliforme, F. semitectum and F. equseti) were present in 3 to 17% of the stalks.
83
58
60
40
52
Did harvest delays, hybrid and plant population influence infection of corn by stalk rot fungal pathogens?
96
89
87
24,000 ppa 30,000 ppa 36,000 ppa 42,000 ppa Average
50
% Stalk Lodged
Between Date 1 and Date 2, little yield loss (
