Summary

 

·         Corn yields are good to excellent in most areas this year, but stalk rots and premature death may lead to severe crop lodging and potential yield losses for some growers.

·         Assessing crop and field conditions is essential to the decision-making process for handling severely lodged corn.

 

Corn field flattened by strong winds. Stalk rots weaken the stalks and predispose the corn crop to this type of lodging.

·         Harvesting lodged corn is more efficient if appropriate tech-niques are followed, proper equipment settings and adjust-ments are made, and specialized reels and cones are used.

 

·         Some yield losses may be expected when corn is severely lodged, especially when green corn stalks are lodged.

 

·         Grain quality will be reduced when ears are on the ground or near it (within eight inches.) This corn should be dried using a continual-flow dryer at temperatures below 160 degrees F.

 

Introduction

Root lodging induced by corn rootworm damage to roots.

 

Corn with high yield potential may be especially vulnerable to  stalk or root lodging as the ear develops and becomes weight-bearing on the plant. A number of factors may lead to  to corn lodging, including the following: 

·         Root lodging from corn rootworm feeding on roots

·         Diseases such as anthracnose, Gibberella, Fusarium and

Diplodia causing stalk or root deterioration

·         Wind blowing over corn plants that are weakened

by rootworm feeding or stalk rots

·         Strong winds blowing over green corn stalks before maturity 

Harvesting and handling grain from a lodged corn crop may be difficult, especially if the lodging occurred early in the season, or is so severe that the crop is flat or nearly flat on the ground. When lodging occurs, growers should carefully assess plant and field conditions and schedule the worst fields for early harvest. Harvest speed and direction of travel may need to be modified. Equipment must be adjusted properly, and specialized reels and cones may be necessary to bring the stalks into the corn head. If grain quality is reduced, proper drying and handling can prevent additional deterioration. These techniques to evaluate and manage a severely lodged corn crop are further discussed in this Crop Insights.  

Assessing Plant and Field Conditions

Step 1. The first step in the process of assessing a lodged corn crop is to identify the extent of the problem. Is the lodged corn isolated in only one area of the field or spread throughout the field? Are only one or two fields affected, or is the problem prevalent in many or all fields?  

Step 2. The next step in assessing the problem is to identify the type of lodging. Determine whether the corn is root or stalk lodged or both. Check to see if stalks are crimped while still green, or whether stalks are broken completely off. Are the roots secure in the soil or easily pulled out? Determine the height of the plants and especially the ears above the ground surface. Are the ears on the ground or four, eight or twelve inches above it? 

Step 3. The third step is to determine the developmental stage and the condition of plants and ears. Look for diseases such as anthracnose, Gibberella, Fusarium or Diplodia that could cause continued deterioration of the stalks (see Butzen and Dolezal, 2000). Assess the stage of development when the plant lodged. Determine the moisture content of the grain, which will help to decide when to harvest.

 Harvest Considerations 

Harvest timing. Lodged fields should generally be harvested as soon as possible, which may be earlier than grain moisture would dictate. The goal is to gather the crop before further reduction of stalk integrity or grain quality. However, if stalks are green or wet it is usually beneficial to let them dry for seven to ten days if possible. This will help move the plant material through the combine and minimize the amount of vegetative plant material in the harvested grain. In some cases, grain may be allowed to mature before harvest if this can be done without further significant reduction in crop quality. 

Lodged or standing fields first? In most situations, it is better to harvest lodged fields or field areas before the well-standing fields. This strategy must be evaluated on a case-by case-basis, however. If better-standing corn is ready for harvest, it may be more efficient and cost effective in some cases to harvest it first, before lodging increases there.  

Speed and direction. In order to pick up and save more ears from lodged plants, slower than normal ground speeds are required. A general recommendation is to harvest at speeds of two to three miles per hour. Under severe stalk lodging conditions, harvesting against the direction of the lodging is usually an advantage. For example, if the corn plants are lodged toward the east, begin harvesting from the east. Harvesting from the west in this example may further lodge the plants, making it almost impossible to pick up the ears.  

Strategies for flat fields. If the crop or ears are eight to ten inches or more above ground level, then it will likely dry to some extent and the corn can be harvested with a low-profile corn head. If the crop or ears are four to six inches or less above ground level, then the corn will not likely dry and a reel mounted on a corn head or a soybean platform may need to be used to get the crop harvested. Some fields may lodge worse as time progresses, especially if a stalk rotting disease such as anthracnose is present. Watch these fields closely. You may need to compromise between letting the corn dry and harvesting before stalk lodging becomes worse.  

Soybean platform head may help. If plants are extremely lodged and stalks and roots are badly deteriorated, a high number of ears may be lost over the outside snouts of a regular corn head. This is especially true if roots are easily pulled from the soil during harvest. In such cases another harvest option is to use a soybean platform head to completely cut the plants off. This may reduce the instances of corn trash plugging the head as well. 

Equipment Settings and Adjustments 

The following equipment settings and adjustments are recommended when harvesting severely lodged corn: 

Concaves. Removing every other wire from the concave improves grain quality and helps prevent matting. However, this allows more cobs in the grain, which increases drying requirements and may reduce grain quality during storage. 

Head speed. When ground speed is reduced, it is also necessary to reduce gathering-chain speed and snapping-roll velocity to maintain a synchronous relationship.  

Head clearance. Adjust the gathering chains and the rolls inward as closely as possible to adequately grip rotten stalks with no center core. Stalks in this condition collapse to a thickness of approximately 1/8 inch when squeezed.  

Head height. Combine snouts and gathering chains should be positioned as closely to the ground as possible to pick up down corn.  

Deck plates. Hydraulic deck plates will be an advantage because plates can be instantaneously adjusted to strip the ear from the stalk and leave the trash behind in the field.  

Add-on snouts and reels. Use plastic snouts and reels to help pick up lodged corn and move it off the corn head and into the combine. Below is a list of manufacturers and dealers for combine snouts and reels along with some information and experience with use of the equipment. 

The Kelderman reel for the corn header has worked very well for harvesting severely lodged corn. The reel moves the corn off the header and into the combine to allow the combine to continuously move forward. Without the reel the operator would need to stop repeatedly to clear the corn head of stalks and ears that pile up. 

Kelderman Equipment             2686 Highway 92 East  
Oskaloosa, IA  52577-9685      Phone: 800-334-6150
http://www.keldermanmfg.com

 

The Meteer corn reel is very similar to the Kelderman reel. Its revolving fingers help to feed lodged corn into the head, saving down corn that would otherwise be lost. Speed of travel must be reduced, however.

 

Meteer Manufacturing     RR1, Box 221     Athens, IL  62613

Phone: 217-636-8109      http://www.meteer.com

 

Kelderman corn reel for harvesting lodged corn.

The Roll-A-Cone Manufacturing Company has two different types of plastic cone attachments, one for a corn head and the other for a soybean-type head.

 

Role-A-Cone for harvesting down corn

Roll-A-Cone Mfg. Co.    Rt. 2, Box 25    Tulia, Texas  79088

Phone: 806-668-4722      http://www.roll-a-cone.com

Refer to the reference manual entitled “Quality Grain Care – A Grower’s Quick Reference” by John Gnadke. Page 38 discusses combine settings for high-moisture corn (22 to 35 percent) and page 48 discusses combine settings for better quality food corn. Also be sure to contact your equipment dealer for expert advice on setting and adjusting harvest equipment. 

Yield Losses From Lodging 

The earlier that lodging occurs in the development of the plant, the greater the resulting yield losses. This is because lodging disrupts the flow of water and nutrients from the soil to the ear. 

There are no reliable studies that have measured yield losses from corn lodging that occurs between pollination and maturity. However, when lodging occurs while stalks and plants are still green (“green crimping”), the effects may be similar to that of frost or other premature death of the corn plant. It is therefore worth reviewing two pieces of information that may provide some indication of yield loss when plant death occurs before maturity. 

The chart below shows the amount of expected yield loss if plant death or nutrient and water flow is completely disrupted in the plant such as with a severe frost. Note that if plants have kernels with ½ milk line (R5.5) the plant still may produce 88 percent of “normal” yield.

Table 1.  Potential grain yield losses after killing frost (both leaves and stalk killed).

Corn development stage	Percent yield loss
R4 (Soft dough)	55
R5 (Dent)	40
R5.5 (50% Kernel milk)	12
R6 (Black layer)	0

Derived from Afuakwa and Crookston, 1984.

Figure 1.  Yield reduction due to premature plant death. Avg. for 6 hybrids over 3 years.  PHII - Plains Sales Area.

 

In a second study corn plants were killed by cutting off the stalk above the ear and removing the living leaves at and below the ear. Yield loss ranged from three to nineteen percent, depending on the stage of plant development when the plants were killed.

 

 Test weight and ear quality. Test weight of lodged corn could be as low as 48 to 50 pounds depending on the hybrid affected and when lodging leads to plant death. Lower test weight grain is more subject to breakage during combining, drying and handling. Cobs may be spongy and grain may be difficult to separate from the cob. Volunteer corn for next year will likely be an issue, but chopping stalks may help.  

Specialty Corn. White and yellow food-grade corn may not make the grade if it does not have the required density or  test weight.  

Drying Lodged Corn

Do not use a portable batch drier if possible. This will further deteriorate grain quality under conditions of wet corn. Lack of drying control is the key issue with a portable drier. Ideally, use an on-farm external continual-flow drier with a three-bin system, with one bin used as a wet holding bin and the other two as cooling bins. Drying temperature needs to be between 150 and 160 degrees F. On-farm drying is especially attractive since some grain terminals may not take wet corn. If growers bring grain into your drying operation, a portable scale will be needed to keep track of weights. The grower should sign an agreement verifying the weight so both parties agree on how much grain was brought in. 

Extremely Lodged Fields 

If lodging is extreme, it may not be profitable to harvest the field. For example, if you are only getting 30 to 50 bushels per acre, test weight is at 48 pounds, and grain moisture is 30 percent the best option may be to leave the crop in the field.

Pencil it out to determine if your decision is profitable.

If it is not profitable to harvest the grain with a combine, one option is to run livestock into the corn field. Know if the crop is insured. Check with your local ASCS office to see if any support is available. 

Safety is Number One Priority! 

There are inherent safety issues when harvesting severely lodged corn. Be sure to stop the combine and engine before making any adjustments or removing piles of corn stalks from the header. Mechanically lock and block the corn head before getting beneath it.  

Keep bearings and chains well lubricated, keep belts tight, replace worn belts and chains and keep all belt and chain guards in place. Other critical safety tips include watching for bystanders and carrying fire extinguishers. Also remember to be patient and take a break to relax for a short period of time before continuing a difficult job. Human safety is the number one priority while harvesting. 

References

 

Afuakwa, J.J. and R.K. Crookston.  1984.  Using the kernel milk line to visually monitor grain maturity in maize.  Crop Sci. 24:687-691.

 

Butzen, S. 1999.  Stalk quality problems in corn. Crop Insights 9 (18). Pioneer Hi-Bred Int'l., Johnston, IA.
http://www.pioneer.com/usa/crop_management/national/corn_stalk_quality_intro.htm

 

Butzen, S. and B. Dolezal. 2000. Managing stalk rot in corn. Crop Insights 10(19). Pioneer Hi-Bred Int’l, Johnston, IA. http://www.pioneer.com/usa/crop_management/corn/stalk_rot.htm

 

Gnadke, J. 1990. Quality grain care – a grower’s quick reference.  Third edition.  Advanced Grain System, Inc. Ankeny, IA.

 

Nielsen, R. and D. Colville. 1999. Stalk lodging in corn: Guidelines for preventive management. Department of Agronomy. Purdue University, Lafayette, IN.
http://nasweb/ais/extbull/1999/in/agronomy/www.agcom.purdue.edu/agcom/pubs/ay/ay%2D262.html

 

Plains Sales Agronomists. 1992.  Yield reduction due to premature plant death. Pioneer Hi-Bred Int’l, Plains Sales Office, Lincoln, NE.