(Above) The root systems of soybean plants with sudden death syndrome will have a deteriorated tap-root and lateral roots will only be evident in the upper soil profile. (Below) Foliar symptoms include interveinal necrosis and spots that coalesce to form brown streaks between the leaf veins with yellow margins. This is the first time this disease has been identified in Nebraska. (Photos by Loren Giesler)

Sudden death syndrome reported, more widespread in eastern Nebraska

Sudden death syndrome of soybean is caused by the fungus Fusarium solani f. sp. glycines. This is a different fungus than the one that causes early season damping off problems associated with soybean stand. This year’s weather pattern -- with early season moisture and moisture at the early reproductive stages -- is conducive to its development. Full symptom expression of the disease is likely evident from mid August to early September. SDS is favored by high yield environments. Soil compaction and high fertility levels also have been associated with increased levels of SDS. One common condition in effected fields has been early planting, which is known to favor the disease. The foliar symptoms start with interveinal necrosis and then spots coalesce to form brown streaks between the leaf veins with yellow margins. Leaves eventually drop with the petiole (leaf stem) remaining attached. The root system will have a deteriorated tap-root and lateral roots will only be evident in the upper soil profile. The root cortex is light-gray to brown and may extend up the stem. Typically, plants can be easily pulled from the ground and a dark blue fungal growth will be visible on the roots. The blue color will not be evident in dry soil conditions.

One disease which can look like SDS is brown stem rot, which we have found in some fields. The key symptom to differentiate the two is internal stem discoloration. If the center of the stem is brown or discolored, it is brown stem rot; if the discoloration is confined to the outer stem margin when split, then it is most likely SDS if the other symptoms match.

We are currently collecting information on how widespread SDS is this year. If you have a field which is exhibiting SDS symptoms, please contact us (402-472-2559, lgiesler1@unl.edu) so we can confirm it and get a better idea of how prevalent this disease is. You also can send a sample of 6 to 10 whole plants (including roots) to the UNL Plant and Pest Diagnostic Clinic. Please put a copy of this article with the sample and you will not be billed for the sample.

Loren J. Giesler
Extension Plant Pathologist

The question is; “Where do these insecticidal seed treatments fit in Nebraska soybean production?” Our major early season soybean insect pest is the bean leaf beetle. In early spring the over-wintered beetles become active and often enter soybean fields as soon as plants emerge. Although the defoliation the beetles cause can appear quite severe, research in Nebraska and elsewhere has shown that it usually does not result in economic damage. Soybean plants can compensate for a large amount of early tissue loss, so it takes a considerable amount of beetle feeding (generally over 50% defoliation) to impact yield.

Coloring of Nebraska's soybean crop had progressed to 15%, ahead of 13% last year but behind 20% average, according to the USDA Nebraska Agricultural Statistics Service. One percent of the crop had begun dropping leaves.

A possible exception to this is in very early planted fields, when plants emerge well before those in surrounding fields. Because the beetles move to soybean fields during seedling emergence, early planted fields usually will have more beetles and suffer the most injury. For those who regularly plant before most of their neighbors and have a history of high beetle numbers, insecticidal seed treatments may be an option. Both products, Cruiser^® and Gaucho^®, have proved effective against early season bean leaf beetle in our insecticide trials.

The other soybean insect pest that some have suggested can be controlled with insecticidal seed treatments is the soybean aphid. Although early season aphid mortality and sub-lethal effects have been observed with insecticidal seed treatments, we do not recommend seed treatments for controlling soybean aphids in Nebraska.

Dr. David Ragsdale and Brian McCornack of the University of Minnesota, have conducted soybean aphid mortality and fecundity (number of offspring) studies to investigate the questions “How long can we expect systemic activity of thiamethoxam to last in the soybean plant?” and “How successful will female soybean aphids be at reproducing on Cruiser-treated soybean leaves?”

In lab bioassays, they exposed soybean aphids to soybean leaves pulled from thiamethoxam-treated plants (50g/100Kg seed) at successively later intervals after planting. They placed aphids on treated leaves and recorded percent mortality and the number of offspring produced per female at 24 hour and 48 hour exposure/feeding times. Ragsdale and McCornack found that soybean aphid mortality was significant up to about 35 days (V3/V4 growth stages), but beyond that point, aphid mortality decreased toward zero and was no longer significant. They also found that soybean aphid fecundity was significantly reduced up to about 40 days after planting. However, beyond 40 days they saw no difference in the number of nymphs deposited by aphids on treated and untreated leaves. The Minnesota researchers concluded that under normal planting dates they did not expect thiamethoxam seed treatment efficacy to hold, particularly under high and/or late season soybean aphid pressure.

In a field study, Dr. Michael Catangui and colleagues from South Dakota State University examined the effect of insecticidal seed treatments (thiamethoxam, imidicloprid, and clothianidin, another neonicitinoid) on soybean aphid populations during R5 soybeans in August. They found that none of the seed treatments significantly reduced aphid numbers or increased yield and concluded that insecticidal sprays would be necessary to control late season aphid infestations. Their findings are similar to our trials in Nebraska.

To date in Nebraska, the soybean aphid has not been an early season pest; it has been a late season pest. Most of our soybeans are planted in May, and we generally don’t begin to see aphids until mid to late July, well past the early vegetative stages. In most fields soybean aphid populations peak in August. This is too long a period of time to expect currently available seed treatments to have a significant effect. In addition, not all soybean fields in Nebraska will have economic populations of soybean aphids, even in the northeast part of the state where we have seen the most soybean aphid injury. This year is a perfect example Why spend money up front when the need may not arise? With the cost of a seed treatment at approximately $12-$14 an acre, it is an expensive “insurance” with a high probability of either not being needed or not being efficacious when used to manage soybean aphid. At current prices foliar insecticide treatments are cheaper than seed treatments and need only be applied when necessary.

In conclusion, we believe that insecticidal seed treatments have a role to play in early planted soybeans for early season bean leaf beetle management, but we do not recommend insecticidal seed treatments for soybean aphid management in Nebraska. Manage soybean aphids by scouting and using economic thresholds. In Nebraska, one well-timed foliar insecticide application, based on two or more field visits, will adequately control soybean aphids and protect yield.

Thomas Hunt
Extension Entomologist
Haskell Ag Lab, Northeast REC
Keith Jarvi
IPM Assistant
Northeast REC

"Grain that is harvested too early will be too wet and too much money will be spent on drying it in the bin," he said. "Let grain dry as much as possible in the field naturally."

However, this means producers will have to pay extra attention to the weather this fall so crops aren't damaged by strong winds or become wetter from rain or an early snow. To make drying in storage bins more efficient, producers can make sure their combines are set properly to clean the grain or use a grain cleaner. This will minimize foreign materials that wind up in the grain bin.

"Residue and trash in the grain bin restrict airflow and make drying more difficult," Jasa said. "Clean grain is better when it comes to saving energy on drying."

Depending on the crops and their rotation, producers also may want to consider not harvesting all of the corn before switching to soybeans. For example, switching to soybeans before all the corn is harvested allows corn fields to continue drying and gives grain driers a chance to catch up. Moisture management on grain will be very important this season to conserve energy, Jasa said.

Farmers also should scrutinize grain hauling costs, Jasa said.

"Make sure you have marketing and storage plans to minimize hauling costs," he said. "Some farmers look at the current grain price, and if they can get a nickel more at another elevator further away they may haul it there. This year, they'll need to make sure it's worth it to make up for higher fuel prices. If it costs 10 cents more to haul it, they would actually be losing a nickel."

While it's probably too late for this year, producers should consider securing diesel, propane and natural gas prices through contracts in the future.

"This was a good year to secure a cheaper diesel price earlier in the year through a contract as diesel prices continue to go up the closer it is getting to harvest," he said.

Another money saver is skipping fall tillage. As the combine is going through the field harvesting the crop, make sure it is properly processing and spreading residue for next year. This eliminates the need to go through the field to shred stalks.

"It's best to skip fall tillage all together to conserve soil moisture, residue and energy," Jasa said.

Jasa also recommended:

• Do routine maintenance on the combine. Make sure the engine is in top shape, filters are clean and everything is properly lubricated.
• Avoid rounded edges on augers and conveyers. Replace rounded and worn edges to maintain proper flow of materials.
• Be sure chains and paddles are in good shape so the combine handles grain properly and money is not wasted on grain and residue slipping through the combine.
• Don't set the thresher more aggressively than necessary to remove grain. An aggressive thresher breaks kernels and uses extra energy.
• As crops dry throughout the harvest season, adjust the thresher because grain becomes easier to thresh the drier it gets.
• Read the owner's manual when making adjustments.
• Make sure all other pieces of equipment, such as grain carts, wagons and augers, are in good shape.
• Don't get fatigued. A sleepy machinery operator will miss adjustments they should be making.

All mechanical grain drying systems use a fan to push air through the grain mass to remove moisture. In deep bed, in-bin drying systems, a drying zone is established and moves through the grain in the direction of airflow. One can monitor the movement of the drying zone through the bin by sampling with a grain probe. Grain above the drying zone remains unchanged or may be slightly wetted by the saturated air that has passed through the drying zone. Grain below the drying zone will eventually come into a state of equilibrium with the incoming air.

In-bin drying

Natural air drying

As stated, natural air drying uses unheated air to dry grain. The time required to push a drying zone through a bin of grain with natural air can be several days to several weeks, depending on the initial and final moisture content of the grain, airflow (cubic feet per minute per bushel, cfm/bu) and air properties (temperature and relative humidity).

Research has found stirring grain being dried with natural air actually prolongs the time required to dry grain because it disrupts the drying zone, resulting in exhaust air leaving the grain mass less saturated.

If a stirring device is installed in a bin being dried by natural (unheated) air, the stirring device should be run during the filling period to reduce the pack factor from the filling operation, redistribute fines and level the grain. Stirring should then be discontinued to allow a drying zone to develop in the grain. Since the bottom of the bin will be somewhat over-dried, a final stirring just before the drying zone is pushed completely through the bin will help equalize the moisture content of the grain.

Table 1. Effect raising the air temperature has on relative humidity. Air Temperature Relative Humidity 50 72 60 50 70 35 80 25 90 18 100 13.5 110 10 120 7.6 130 6 140 4 Assumptions: Elevation 1,000 feet. Dew point 41.4oF.

Heated air drying

Drying time can be significantly reduced by adding heat to the process. Heating air does not reduce the quantity of water vapor in the air but it does increase the amount of water vapor the air can hold by lowing the relative humidity. Therefore heated air has the potential to pick up more moisture per unit volume passing through the grain than unheated (natural) air. When adding supplemental heat, the relationship between temperature rise and relative humidity is not linear (Table 1).

A rough rule of thumb is the relative humidity drops by one-half for each 20^oF rise in temperature. For example, natural air at 60^oF and 50% relative humidity will have a relative humidity of 25% if heated to 80^oF. Adding another 20^oF to raise the temperature from 80^oF to 100^oF cuts the relative humidity by about half again and results in a drop to 13.5%. The third 20^oF rise to 120^oF lowers the relative humidity by about half again to 7.6%. The notable point is the second 20^oF increment of added heat results in half as much reduction in relative humidity (half of half) and the third increment results in only one-eighth as much reduction (half of half of half). To minimize energy cost for drying grain, keep the temperature rise to a moderate level. The biggest savings in drying time versus energy input for in-bin drying systems is achieved with the first 20^oF to 40^oF increase in air temperature.

Table 2 presents the results of a computer simulation comparing the electrical and propane energy costs for batch-in bin drying with natural air at 60^oF and 50% relative humidity compared to heating the air to 80^oF or 95^oF. Note the drying time versus total energy cost comparison in the last column. Boosting temperature by 20^oF to 80^oF resulted in a drying time only 42% as long as natural air with an energy cost penalty of 39%. Boosting temperature by 35^oF to 95^oF resulted in a drying time only 31% as long as natural air drying but with an energy cost penalty of 74%.

Management of stirring devices is different for heated air drying than natural air drying, especially for high temperature drying (over 40^oF temperature rise). The relative humidity of the incoming air is so low with heated air drying, the grain on the bottom of the bin is over-dried by several percentage points by the time the drying front is pushed through the full depth of the grain. Stirring devices, if installed, should be run continuously with high-temperature heated drying systems to help equalize the moisture content of the grain mass and avoid over-drying at the bottom of the bin.

Table 2. Comparison of total energy consumption and cost vs drying time for three drying scenarios. Initial and final kWh - cost $ Gal. LPG Drying Total cost % Time - % cost air temperature (for aeration fan) - $LPG time, hr for energy (vs. natural air drying) Natural air 60oF and 50% RH 3,073 - $246 0 - $0.00 94.6 $246 100% - 100% Heated to 80oF 1,279 - $102 191.2 - $239 39.4 $341 42% - 139% Heated to 95oF 952 - $76 280.4 - $351 29.3 $427 31% - 174% Assumptions: Fan = 25 hp centrifugal. Grain = Corn. Initial moisture = 20.5%; final = 15.5% moisture. Bin diameter = 30 feet. Grain depth = 8 feet. Bushels per batch = 4500 bushels. Electrical: 32.5 kWh per hour for fan operation at $0.08 / kWh = $2.60 per hour. Propane: $1.25 /gallon, 90,000 BTU per gallon.

In-bin layer drying

If a producer has several bins equipped with drying fans and is able to switch over from filling one bin to another in a reasonably short time, filling and drying several bins in layers could reduce drying time and energy consumption by 20-35% as compared to completely filling each bin in turn before beginning to fill the others.

Aeration fans operate on a static pressure (measured in inches of water) versus air output (cfm) curve. Static pressure increases with greater depths of grain in the bin and with higher airflow (cfm) per bushel. The higher the static pressure the fan must overcome, the fewer cfm the fan can push through the grain.

Since drying time is a function of the airflow per bushel (cfm/bu), both factors work in our favor when drying in layers as opposed to starting with a full bin - whether using natural or heated air for in-bin drying.

New Market Journal features Gudmundsen Lab Open House Ethanol production and the use of by-products for feed was the focus of the Gudmundsen Open House. Todd Sneller, administrator of the Nebraska Ethanol Board, talks about energy prices and ethanol. Galen Erickson, UNL extension beef feedlot specialist, addresses nutritional aspects of Ethanol by-products for feed. Terry Klopfenstein, UNL professor of animal science, talks about research on using by-product feeds with forage. Also on the program: Livestock Markets: Beef -- Dillon Feuz, UNL Extension Marketing Specialist Energy Bill -- Nebraska Rep. Tom Osborne Dedication of the Wagonhammer Education Center -- John Owens, UNL Vice Chancellor, IANR Weather -- Al Dutcher, UNL Extension State Climatologist Also watch for the Sept. 9-11 show: "Market Journal at the Nebraska State Fair." For information about broadcast times and availability, check the Market Journal program schedule.

If you live in western Nebraska, you may be under the belief that it has been unusually wet this year. In comparison to 2004, you would be correct. Through August 29, Scottsbluff had received 16.34 inches of moisture, 3.68 inches above normal. In 2004, Scottsbluff recorded 6.50 inches of moisture in the same period. Similar patterns have been noted in the Sidney and Valentine areas. Valentine received 22.67 inches of moisture in 2005, compared to 12.90 inches in 2004; Sidney received 16.11 inches in 2005, compared to 10.34 inches in 2004.

Central and west-central Nebraska precipitation trends are generally closer to normal, but are substantially improved compared to 2004. Grand Island had received 23.84 inches through August 29, compared to 14.07 inches in 2004. Hastings received 17.95 inches, compared to 16.76 inches last year. For the year Grand Island is 4.14 inches above normal, while Hastings is 1.87 inches below normal. Conditions across eastern Nebraska are showing the most variability in precipitation with Lincoln and Omaha showing negative departures for the period of 1.87 and 1.14 inches, respectively. Lincoln received 19.00 inches of moisture in 2005, compared to 16.76 inches in 2004. Omaha received 19.30 inches this year, compared to 21.36 inches last year. The Norfolk area is currently 1.97 inches above normal for the year at 19.91 inches, but down considerably from 2004 when 29.53 inches had been recorded though August 29.

What has been the significance of above normal precipitation across western Nebraska this year? Significant improvements in streamflow rates on the Platte River upstream of Lake McConaughy are being observed. Flow have been averaging 900 cfs during the past couple weeks, compared to virtually no flow during the same time last year. As of August 29, Lake McConaughy stood at an elevation of 3205.2 feet above sea level, compared to 3199.4 feet last year. It is now 7.6 feet higher than the record low elevation set last September at 3197.6 feet above sea level. In terms of capacity, Lake McConaughy is currently 25.5% full.

If current streamflow rates continue through the fall, coupled with normal winter precipitation, it is possible that Lake McConaughy will top 50% of capacity prior to the onset of the 2006 irrigation season. In addition, it has been exceptionally wet in the Wyoming region of the Platte River basin during the past few months. Above normal snowfall this winter could easily translate into a higher proportion of the spring snow melt making its way into the Platte watershed.

The Republican River watershed has begun to slowly respond to the increased precipitation events in 2004, but average flows within the Nebraska border consistently have remained in the lower 20 percentile of historical flow rates. It will be necessary to see a wet fall and winter for substantial improvements to occur within the watershed. Reservoirs levels within the watershed should be improved by the start of the 2006 production season, but will probably not approach the improvement potential of the Platte River basin.

The latest long range weather outlooks for this winter and spring fail to offer any clear indication of defined precipitation pattern across the central Rockies and central High Plains. Temperatures do show a warmer than normal tendency in the December-February period. At present, there is no sign that the upper atmospheric ridge that blocked the movement of significant storm activity into the central United States is trying to re-establish itself. Therefore, the current pattern of frequent storm systems moving into the central United States should continue with a minimum of normal precipitation expected.

Soil water recharge

Since there is no clear delineated precipitation tendency shown for this fall, eastern Nebraska dryland corn producers can evaluate their risk of sub-normal soil moisture recharge through the fall and spring by simply tracking the amount of precipitation received during the October-April period. Studies have concluded that if 12 inches of moisture is received during the off-season, coupled with normal growing season precipitation, normal corn yields can be expected. These 12 inches would translate into full recharge of the top 4 feet of soil profile. For each inch of moisture short of 12 inches in the off-season, coupled with normal growing season moisture, expect a 2.5-5.0% yield reduction.

October and November precipitation are extremely important in the soil moisture recharge equation. If 5.0 inches of moisture is received during the two-month period, there is a 50/50 chance of obtaining 12 inches of moisture through the end of April. If only 2.0 inches are received during the period, there is a 22% chance of obtaining full recharge, increasing to 33% if 3.0 inches are received. If conditions are wetter than normal and there is 5.0 inches of precipitation, there is a 62% likelihood of receiving 12 inches by the end of April, increasing to 72% if 6.0 inches is received during the two-month period.

The data used in the listed risk analysis scenario is based on 110 years of climate data. No forecasting techniques are included in the probability calculations, as they are entirely based on historical climate events. This information simply gives the producer a means of assessing his risk prior to undertaking 2006 productions decisions.

Al Dutcher
Extension State Climatologist

Check now for uniformity of water application

For center pivots, problems with uniformity usually occur in a circular pattern and not in the planted row direction. Because the center pivot cuts across crop rows planted in straight lines, the combine integrates the good and bad areas so that it’s not always easy to tell if water distribution was an issue. Even with a yield monitor, some water distribution problems can be masked by the number of rows entering the combine. In severe cases, water distribution issues can be exhibited by shorter corn or by obvious water stress during the growing season. More subtle problems may be documented by soil water monitoring.

Water distribution uniformity is impacted by elevation changes in the field that are significant enough to cause more or less water to exit each sprinkler than the original system design called for. Pressure regulators installed on each sprinkler will tend to minimize nonuniformity due to field topography. The University of Nebraska recommends that if the field elevation difference results in a change in flow rate that is more than 10% different than the original design, regulators should be installed.

Another source of nonuniform water distribution can be the position and spacing of the sprinklers on the system. For example, low pressure spray nozzles mounted on drop tubes and spaced greater than 10 feet apart can result in water distribution uniformity issues if the sprinkler is operating in the crop canopy. This issue has emerged during the past few years when the number of irrigation events per year has been high and little rainfall has been recorded in many areas of the state. Thus, even minor nonuniform water distribution problems will tend to accumulate over the season. Sprinkler spacings should be 7.5 feet or less if the sprinkler is operating in the crop canopy -- 5 foot spacings are preferable.

Non-uniform yields can be due to a number of factors. If water distribution issues are suspected, the easiest way to evaluate the problem is to isolate and hand harvest a small area or harvest two rows at a time in the suspect area of the field. The best place to determine the direct link between water distribution and yield is where the center pivot becomes perpendicular to the crop row direction. At this point yields can be tied directly to the position on the center pivot and to a series of sprinklers on the system.

If the hand harvest approach is taken, it is best to harvest and shell the ears from two rows of corn at least 20 feet long. After shelling the corn, weigh the corn wet and then take a moisture sample so that the yield can be converted to the standard 15.5% water content. By comparing the yields of side-by-side rows, it is easy to determine if water distribution uniformity due to the sprinkler position and spacing are the cause.

Systems with sprinklers mounted on top of the pivot pipeline can have problems too. In some cases, a series of sprinklers may be installed out of order. To eliminate this possibility, check the computer printout for the sprinkler package and check to see that the right sprinkler is in the right place. Though misplaced sprinklers are not common on new systems, worn out or broken sprinklers are often replaced with whatever happens to be available at the time. Over time this could lead to water distribution uniformity problems that are not the result of the original system design.

Another cause of nonuniform irrigation can be broken or plugged sprinklers. If sprinklers are operated within the canopy, plugged sprinklers or other distribution problems may not be directly observed. The best way to identify incanopy sprinklers that are not operating properly is to walk along the system during the first irrigation. Later in the growing season the sprinkler operation can be evaluated on the access road. Plants can be good indicators too. Prior to harvest try to select a high point such as a hill, pivot tower or the combine, from which you can observe the field and see any potential problems.

Uniformity problems with furrow irrigation will need to be evaluated a little differently. For example, a patchy area in the field could receive too little water as a result of soil compaction. A soil probe will often find any compaction layers that may be causing problems. Compaction also can be traced back to spring tillage operations, especially if the soil was wet when tillage was being done. These areas will show up as straight lines through the fields in the direction of tillage.

If irrigation timing is the problem, those differences should show up according to the width of irrigation sets that are used and will likely be most evident at the far end of the field where water application was less. Seldom will you find uniformity problems at the head end of the field.

Regardless of what type irrigation system is being used, uniform water application is becoming more important as water supplies become more limited and fuel costs increase. As the season draws to an end, make sure you look for crop height differences that may reflect yield reduction caused by nonuniform irrigation practices.

Test corn stalks for nitrogen; adjust rates accordingly

(Above) Take an 8-inch segment of cornstalk from 6 inches to 14 inches above the ground. (Right) Stalk samples should be kept cool and wrapped in paper rather than plastic to avoid mold.

Taking corn stalk samples now can help determine if the corn was under, adequately or over fertilized with nitrogen. If the nitrogen applied this year was greater than that recommended by the University of Nebraska and this fall’s stalk nitrate samples indicated excess nitrogen, consider reducing nitrogen rates for next season.

Table 1. Winter wheat seeding data and yield at North Platte. Seeding date Yield (bu/ac) September 2 2 September 15 27 September 25 42

In one University of Nebraska test a replication located in a low area yielded 70 bu/acre while the entire plot averaged 21 bu/acre because it had more soil water.

The recommended seeding dates for Nebraska’s winter wheat vary substantially from one end of the state to the other – from September 1 in the extreme northwest area to October 1 in the southeast tip – and have been proven and verified through years of research and farmer experience. Some years an earlier seeding may have an advantage and some years a later date may have an advantage, but in the long term, the suggested seeding dates will give the highest average yield.

The recommended seeding date represents a goal for seeding completion. As farm size and the number of acres increases for individual farmers, so does the length of time needed to complete seeding. The goal should be to have all the wheat planted by the ideal date. Plan your field order for planting accordingly. For example, plant higher elevation fields and those containing sandy soil first and leave lower fields and those with higher clay content until last.

Figure 1. Recommended planting dates for Nebraska winter wheat.

If the seeding date is delayed or growing conditions prevent or delay root growth to the dual placement fertilizer band, seed fertilizer placement is the preferred application method (Figure 1). Poor root growth for whatever reason limits root-fertilizer contact and tillering, which affects yield. Much of the grain yield of winter wheat occurs on tillers that develop from buds in the axils of lower leaves. Under normal conditions, as much as 70% of the grain yield comes from tillers. Tillering also enables the plant to adapt to different conditions. Few tillers develop when moisture, nutrition, and other conditions are poor, whereas numerous tillers that increase the yield potential form when conditions are favorable.

Date of seeding greatly affects development of tillers in winter wheat. Seeding during the optimum period enables wheat to form sufficient but not excessive tillers. Early seeding results in too many fall tillers, which may compete with each other, become diseased, and deplete soil moisture so that grain yields are low. Late seeding gives plants little time to develop tillers, resulting in an inadequate numbers of spikes (heads) for high yields the following spring.

Senescence and death might eliminate excessive tillers that form during the fall. Conversely, if too few tillers develop during fall, additional tillers may form during spring; however, the yield potential may differ between tillers that develop during fall and those that develop during spring.

A study by Kansas State University to determine the seeding date effects on tiller development and productivity of winter wheat was conducted in a corn/soybean rotation at Hutchinson, Kansas. Two hard red winter wheat varieties, Jagger and 2137, were planted on four dates in the fall of 1995 (Table 2). The first date, September 28, was during the early part of the recommended period, September 26 to October 20. The second date, October 11, was one day after the Hessian fly-free date, and the last two dates, October 28 and November 11, were after the recommended period. Wheat varieties were planted at 60 lbs/ac of seed in plots. Plots received 70 lbs N/A and 25 lbs P/A before planting and 50 lbs N/A in late February 1996.

Data for Jagger and 2137 were pooled, since results for the two varieties were similar. Nearly equal numbers of seedlings emerged after all planting dates except October 11, when considerably more plants emerged (Table 2). Plants from the first two dates tillered profusely, developing most of their tillers before they became dormant in late fall. Plants from the latter two seedings did not form any tillers before they became dormant, but those from the October 28 seeding developed a few tillers over winter. Only 46% and 65% of the fall tillers on plants from the first two dates, respectively, survived the winter, whereas 100% of the fall tillers on plants from the last two dates survived. About 50% to 60% of the surviving fall tillers from the first two dates formed spikes, while approximately 80% of the surviving tillers from the last two dates produced grain.

Plants from the first three seeding dates developed nearly 600 spring tillers per square yard, but plants from the last date formed only 213 spring tillers per square yard (Table 2). About 30% of the spring tillers from the first two dates, 45% of the spring tillers from the third date, and 68% of the spring tillers from the fourth date produced grain. The total number of productive spikes ranged from 260 to 552 per square yard or 1.8 tillers per plant from the last seeding to 3.4 tillers per plant from the first seeding.

Table 2 also lists the yield from the four seeding dates. These dates need to be adjusted for the area in Nebraska to be seeded.

Several factors were considered when developing the recommended seeding dates (Figure 2). In the Panhandle, the dates depend on elevation. Producers can determine the ideal date for each field by knowing the elevation. Using a starting point of September 15 for 3500 feet, one day should be added for each 100 foot decrease and subtracted for each 100 foot increase in elevation. For the rest of the state, September 25 or later seeding dates are recommended to avoid Hessian fly infestation.

Delayed planting dates also may be due to a need to avoid wheat streak mosaic virus, Russian wheat aphid, crown and root rot, and too much fall growth. Excessive fall growth causes excessive moisture use and stress. There are several other reasons for planting early. One is to get adequate ground cover to avoid erosion from wind and water. Another is to get adequate plant growth to assure winter hardiness. A third reason is to quicken maturity the following summer and avoid excessive heat stress.

The map is a guide rather than an absolute deadline. Each producer should make changes to ensure the planting dates fit the conditions of his or her farm.

Bob Klein
Cropping Systems Specialist
West Central REC

Table 2. Mean date and number of plants that emerged; maximum, surviving, and productive fall tillers; maximum and productive spring tillers; and total productive spikes by Jagger and 2137 wheat varieties planted on four dates (Kansas State University at Hutchinson, Kansas). Date (1995) Spring Fall tillers tillers Total Plants (no/yd2) (no/yd2) spikes Yield Planting Emergence (no/yd) Max Surviving Productive Max Productive (no/yd2) bu/ac Sept. 28 Oct. 12 141 1266 578 281 584 195 476 39.0 Oct. 11 Oct. 18 207 916 594 360 659 192 552 57.7 Oct. 28 Nov. 15 141 183 183 152 600 272 424 54.8 Nov. 13 Nov. 30 143 147 147 117 213 144 260 30.2 LSD (0.05) 38 136 191 92 147 53 106 4.9

If we examine the seed size in the UNL Extension Fall Seed Guide 2005 (EC05-103), the smallest winter wheat seed had 20,110 seeds/lb and the largest had 12,910 seeds/lb. Some years the largest seeds will have fewer than 10,000 seeds/lb. All seed should be cleaned and the small and cracked seeds eliminated. Shriveled seed can reduce yields because germination is slower emergence is reduced.

Table 1. Seeding rate for winter wheat with 18 seeds/foot of row. Row Feet of Wheat seeds/lb spacing row/acre 12,000 13,000 14,000 15,000 16,000 17,000 18,000 ------------------- lb/acre of seed --------------------- 6" 87,120 131 121 112 105 98 92 87 8" 65,340 98 90 84 78 76 69 65 10" 52,272 78 72 67 63 59 55 52 12" 43,560 65 60 56 52 49 46 44 14" 37,337 56 52 48 45 42 39 37

Winter wheat will respond to a limited range of seeding rates without affecting yields. Using seeding rates below that range can lead to excessive tillering. It also may delay maturity, increase weed competition and fail to make use of full yield potential; however, rates above that limited range may increase costs, increase lodging and possibly reduce yields.

Too much competition, even among the small-grain plants, may lead to fewer kernels per head and lower kernel weight. The key is an optimum plant population with uniform distribution for efficient use of available resources.

A review of how seeding rate affects yield potential is helpful. On the average, there are 22 seeds per head and 5 heads per plant, or 110 seeds per plant. With an average seed size of 15,000 seeds per pound or 900,000 seeds per bushel, a pound of average-sized seed with 80% germination and emergence has a yield potential of approximately 1.5 bushels per acre. Seeding 40 pounds of seed with a weight of 15,000 seeds per pound has a yield potential of 60 bushels.

Seed cleaning and sizing is essential to remove straw, chaff, dirt, stones, weed seeds, and broken, diseased or small shriveled kernels. Generally, seed cleaning will add 1 to 2 pounds to the seedlot’s test weight by removing the small kernels. Taking a germination test is essential to determine the seed viability. After seed germinability has been determined, the seeding rate can be determined. Seed for planting should be above 85% germination.

There are several views on how many winter wheat seeds the grower should plant per acre. Floyd E. Bolton, crop scientist at Oregon State University, says 18 seeds per foot of row seems to be the point of diminishing yield increases, no matter what row spacing from 6 to 18 inches. For dryland winter wheat in western Nebraska row spacings of 10 to 14 inches are recommended. Narrow row spacing offers an advantage for weed competition. For irrigation, row spacings of 6 to 8 inches are preferred. Following is a table on the pounds of seed/acre for 6 to 14 inch row spacings and seed sizes of 12,000 to 18,000 seeds/lb based on 18 seeds per foot of row. If planting is delayed, increase seeding rates up to 50% on dryland fields and up to 2.7 million seeds per acre on irrigated fields to offset the reduction in tillering that occurs with cooler temperatures.

Tom Dorn, Extension Educator in Lancaster County: Corn is fully dented and most varieties are very close to maturity. At this point rain is not going to have much effect on corn yield. Group 2.2 - 2.5 soybeans are starting to turn color and group 3.0 - 3.5 beans are still filling the pods. All varieties of soybeans in areas receiving rain this past week will benefit and have increased yields. Group 3 and longer beans could still use a couple more inches of rain, if it comes right away. Most fields of grain sorghum have turned color and are in mid to late dough stage or beyond, depending on variety. Grain sorghum yield potential is about average. The soil moisture conserved by no-till farming is going to show in the combine tank this year.

Gary Lesoing, Extension Educator in Nemaha County: The rains received in mid-August were very beneficial to this year’s crops, especially soybeans. The soil moisture conditions are generally favorable for continued normal crop development. Most soybeans are in the pod filling stage. In scouting fields I have seen fairly high numbers of bean leaf beetles, with significant defoliation and some pod damage. I also have seen an increase in soybean aphids, although levels are well below treatment levels. Last week most fields had populations of less than 50 per plant, but there were a few plants with populations of almost 100 aphids per plant, still well below the treatment level of 250 aphids per plant. Corn is maturing and yields should be quite variable, depending on rainfall, hybrid and planting date. In some fields there should be some very good corn yields, but in other fields the hot, dry stressful weather in July will take a toll. Since the rains pastures have had good regrowth and some fourth cutting alfalfa has just been cut. In some drier areas in adjacent counties, corn has been harvested for silage.

Darrel Siekman, Extension Educator in Merrick County: It has rained about an inch, allowing many producers to start picking up irrigation pipe on the corn. Soybeans will probably need another irrigation or two depending on the rainfall. This last rain is a big help to pastures, newly planted alfalfa and rye. An early corn harvest is imminent.

Douglas Anderson, Extension Educator in Nuckolls and Thayer counties: Some silage -- a very small percentage -- is being chopped for green feeding to feedlot steers. Other fields will be cut as fields dry down. Good rains have boosted hopes of dryland beans and sorghum. Irrigation is almost done in wide areas of Nuckolls and Thayer counties. Alfalfa is responding and will probably have a third cutting.

John Hay, Extension Educator in Pierce, Madison and Wayne counties: Crops in northeast Nebraska are quite variable, depending on soil type and rainfall. Dryland fields in Pierce County are looking rough, especially those in sandy areas. Yields will most likely be down from last year, but probably will be somewhat close to the long-term average. Few insects are causing harm. Aphids are prevalent, but in low numbers. Their season is ending soon and we wouldn’t expect them to be a major problem. There are a few bean leaf beetles, but not really enough to do much harm. Pierce County received nearly 2 inches of rain last week which shut some pivots off and will really help finish off the season. My sentinel soybean plots are turning color and thankfully we haven’t seen any rust.

Sugarbeet growth will continue until harvest, which begins in early October. Water use will average between 1.0 and 1.5 inches a week in September. The biggest concern for sugarbeet growers without a well will be whether adequate soil water will be available for harvest. Alfalfa water use will average between 1.2 and 1.6 inches per week during September.

As the case with any crop, cooler than normal weather will mean less water use and hotter weather will mean more water use. Irrigation wells will keep the crop going until frost. For those without wells, precipitation is needed to meet crop water needs and avoid a premature end to the growing season.

C. Dean Yonts
Extension Irrigation Engineer
Panhandle REC

The carryover volume doesn’t mean 2005 was a “business as usual” year. Irrigators still faced water restrictions and limitations. In anticipation of water shortages this year, a number of acres were planted to spring crops to reduce irrigation needs. Those crops were nearly mature before water entered the canal systems and as a result, water available for those acres could be used on remaining acres.

The irrigation districts are counting on precipitation this fall to help finish crops and avoid late season water stress. This winter, the districts also are hoping for an above average snowfall that will come closer to meeting their normal diversion needs of 1.1 million ac-ft of water. Currently, total water in storage in the North Platte system stands at only 69% of normal. Without above normal snowfall in the Rocky Mountains this winter, the North Platte projects will face another year of short water supplies and North Platte Valley irrigation districts could see their carryover supplies diminish.

C. Dean Yonts
Extension Irrigation Engineer
Panhandle REC

UNL’s Institute of Agriculture and Natural Resources will have more than two dozen exhibits and displays covering topics and issues that impact a large cross-section of Nebraskans. Topics will include:

• Soybean Rust: UNL’s Mobile Diagnostic Lab Monitors Nebraska’s Soybeans
• Food Processing Center: Adding Value to Your Commodity
• Managing Soybean Aphids in Nebraska
• Precision Ag: Technology in Crop Production
• Using Climate Forecasts to Improve Ag Decision-Making
• Economics of Agriculture and Natural Resources
• WeedSoft: High Tech Integrated Crop Management
• Agricultural Tax Management
• Antique Tractors: Memories in Paint and Metal
• Lake Algae Testing, Staying Safe For Fun
• Nebraska’s Water: Our Precious Resource
• New Seed Varieties Grow For You
• Discover 4-H, Discover You
• Pesticide Storage Security

Join Market Journal live

This year's theme is "Making the Critical Difference." The keynote address will be given by Christine Burton, assistant deputy minister of Manitoba Agriculture, Food and Rural Initiatives in Manitoba, Canada. Burton will talk about why women's contributions often are under-valued, the changing role and influence of women in rural development, and how women can make their voices heard on a broad scale.

Registration is $75 before Sept. 3 and $85 afterward. The fee includes workshop materials, registration, breaks, lunch and dinner on Sept. 15, and breakfast and lunch on Sept. 16. Lodging is available by contacting the Kearney Holiday Inn at (800) 248-4460.

Corn conditions rated 5% very poor, 9% poor, 21% fair, 47% good, and 18% excellent. Irrigated fields improved to 83% good or excellent while dryland fields remained at 35%. Ninety-five percent of the crop was in the dough stage, ahead of 91% last year and the average at 93%. Sixty-nine percent of the crop had dented, ahead of 44% last year and 59% for the average. Three percent of the corn crop had reached maturity, ahead of 1% last year but behind 8% for the average.

Soybean coloring had progressed to 15%, ahead of 13% last year but behind 20% average. One percent of the crop had begun dropping leaves. Conditions rated 4% very poor, 11% poor, 28% fair, 42% good, and 15% excellent. This remains above average but below last year.

Sorghum conditions rated 4% very poor, 11% poor, 30% fair, 45% good, and 10% excellent, better than last year and average. Ninety-eight percent of the crop had headed, ahead of last year and the average at 93%. Sorghum coloring was at 47%, ahead of last year at 24% and average at 40%.

Dry bean conditions rated 2% very poor, 7% poor, 27% fair, 52% good, and 12% excellent. Twenty-eight percent had turned color. Twelve percent of the dry bean crop had begun dropping leaves.

Alfalfa conditions rated 5% very poor, 15% poor, 36% fair, 36% good, and 8% excellent. Third cutting was 92% complete, ahead of last year at 81% and the average at 82%. Fourth cutting was 10% harvested.

Proso millet harvest progressed slowly to 3%, ahead of last year at 2% but behind the average at 9%.

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Copyright 2005 by the University of Nebraska

Published by University of Nebraska Cooperative Extension in the Institute of Agriculture and Natural Resources Cooperating with the counties and the U.S. Department of Agriculture

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