|
Management
Weed Control
Fertility
Wheat Production
Disease Management
Insect Control
Alfalfa
Ag Updates/Briefs
|
| ||||||||||||||||||||||||||||||
Skip-row planting is beneficial in dry conditions because it conserves available water early in the season in the unplanted rows. Since plant roots can’t reach and use the water early in the season, more water is available to the plant in July and August, typically the state’s driest months. If drought continues, dryland farmers in eastern Nebraska may want to look at the practice.
Skip-row planting of corn wouldn’t be feasible had it not been for the release of Roundup Ready corn. Roundup Ready corn allows for the use of glyphosate, a relatively inexpensive nonselective translocated herbicide. Roundup Ready Corn 2 adds to the practice by allowing a higher rate of glyphosate and applications later in the season. Not all glyphosate brands may be labeled for Roundup Ready Corn 2. Roundup Ready 2 corn has the NK-603 event. Seed bags may not have the RR 2 logo but all seed identified as GA-21, the old event on Roundup Ready corn, has to be identified as such. See Table 1.
| ||||||||||||||||||
Skip-row planting provides protection from wind erosion: if plants dry up, little is left behind to protect the soil. However, they’ll be more residue where water is available, helping protect the soil from wind erosion.
One may even consider planting in the skip rows the next year and making the previously planted rows the skip rows. This would result in continuous cropping. Research is planned to evaluate this practice. For the trials, fields were conventionally planted and plants in the skip rows were removed July 2. It is estimated that three additional inches of soil water would have been available if the plant two rows, skip two rows system had been used from the start of the season.
In a plant-two, skip-two system every row would be an outside row. In Iowa State Research corn rows bordering soybean (see Figure 2) produced 20% more on average than rows 3 and 4. We try for 0.5 lb ears for maximum production, but these outside rows would weigh 0.6 lbs. Would rows with no crop next to them produce even higher ear weights under optimum conditions?
Table 2 lists ear weights and yields for a plant-two skip-two row system with several plant populations. Figure 3 illustrates how skip-row planting might be achieved with various sized planters. Only with a six-row planter, which effectively become an eight-row planter, do you benefit from planter size. With the six-row planter you need to extend the markers to skip over the two rows not planted. When possible, GPS should be used for guidance rather than a disc marker which plants weed seed.
In summary, to make the skip-row system work:
Bob Klein
Extension Cropping Systems Specialist
West Central REC
Alex Martin
|
Past research in Nebraska on medium- and fine-textured soils did not find the use of starter fertilizer to be economical, but this research was conducted primarily under tilled conditions. Results of some studies in other states show a higher probability of corn response to nitrogen, phosphorus, and sulfur in starter fertilizer under no-till conditions. Some studies, but not all, find the placement method to be important, and there is some indication that soil type and topographic position could be important.
Fourteen trials were conducted in eastern Nebraska in 2002 and 2003 to determine corn response to starter fertilizer under no-till conditions. Eight trial sites were on farmers’ fields and three each were conducted at the Haskell Ag Lab near Concord and the Agricultural Research and Development Center near Mead. Sites were selected to represent diverse soils and topographic positions.
Eight starter fertilizer treatments were compared:
Results
Soil pH ranged from 5.4 to 6.8 (Table 1). Soil organic matter ranged from 1.9% to 3.3%. Bray 1 phosphorus ranged from low to very high and was higher in the 0- to 2-inch depth (median = 35 ppm) than in the 2- to 8-inch depth (median = 9.6 ppm). The potassium level was high at all sites.
On average, there was a corn yield increase of 7.5 bushels per acre with starter fertilizer, with a slightly greater increase with in-furrow placement of nitrogen plus phosphorus as compared to other starter treatments (Figure 1). Response was greater under irrigated conditions (Figure 2) than under dryland conditions although several dryland trials experienced severe water deficits. Most of the response occurred where soil Bray-1 phosphorus was less than 15 ppm (Figure 3). This suggests that phosphorus is more important than nitrogen in the starter fertilizer.
| ||||||||||||||||||||||||||||||||||||||||||
Conclusion
The increase in corn yield under irrigated conditions, especially if soil phosphorus is less than 15 ppm, is sufficient to justify applying phosphorus and maybe nitrogen in a starter fertilizer (e.g. 10-34-0 or 11-52-0) at about 10 lb phosphate per acre. Yield increases with starter fertilizer under dryland conditions were smaller and less frequent but starter fertilizer use may be profitable in adequate rainfall years. In-furrow placement was as effective, or more effective, than over the row or 2x2 placement.
Charles S. Wortmann
Extension Nutrient Management Specialist
Fusarium
If conditions are cool and without excessive moisture, Fusarium will be our main seedling disease problem. Fusarium symptoms tend to be tan-to-reddish brown lesions that cause the root or mesocotyl to shrivel. When infections move into the crown the crown tissue will be darker than a healthy crown which is light to tan. The decayed crown cannot support the moisture needs of the plant after the weather warms up so plants will suddenly wilt and die. A damaged crown can lead to later problems as the fungus develops and spreads as stalk rot.
Pythium
If conditions are wet and cool, Pythium will be our main problem for seedling disease. Wet soil conditions and soils with high clay content that do not drain well are favorable for Pythium. Several species of Pythium can rot the seed prior to germination or attack the young seedling before or after emergence. Symptoms of Pythium are typically a brown discoloration and rotting of the exterior portion of the root and mesocotyl. Like Fusarium, these infections can spread into the plant’s crown. Crown infections cannot be differentiated based on symptoms. Early season damage from Pythium will also result in more stalk rot as the plants mature.
Management
Fungicides are the main seed treatment to prepare for potential damage from seedling diseases. While most corn seed is treated, the treatment may not last long enough to protect the seedlings past the critical stage if development is slowed by cool temperatures. In fields with a history of significant Pythium problems, producers might consider increasing the rate of mefenoxon (Apron) on the seed. After a stand has been identified as having a seedling disease problem this spring, careful cultivation to promote nodal root development can help plant recovery.
Loren J. GieslerCorn seedling diseases and protective fungicides
Should wet and/or cool weather continue into planting, corn stands could be affected by seedling disease. Damage to the seed or mesocotyl while the seedling is still strongly dependent on the seed for nourishment will typically result in severe stunting and/or seedling death. The critical growth stage for this type of injury is usually before the V2 stage. Anytime corn is developing slowly, it is at greater risk of such damage. The two main seedling disease problems in Nebraska corn are Fusarium and Pythium.
Extension Plant Pathologist
|
Corn flea beetles overwinter as adults in protected areas near corn fields. They become active in April and feed on a variety of grasses before corn emerges. Corn flea beetles can directly injure corn by feeding on seedling plants; however, probably more importantly they vector the bacterium which causes Stewart’s wilt. (For more information, see the NebGuide, Stewart’s Wilt of Corn in Nebraska, G1462.)
To minimize damage:
Bob Wright
Extension Entomologist
| ||||
Check alfalfa for winter injury
|
Evaluate alfalfa stands early this spring. For maximum yields, older, dryland fields need 40 new shoots per square foot coming from two or three plants. If you find fewer than 30 shoots, new fields may need to be planted. Very productive sites, such as irrigated and sub-irrigated fields, should have at least 55 shoots per square foot coming from four to six plants. Consider planting new fields if your current stands are thinner than 40 shoots. A loss of about one tenth ton in yield can occur for every lost shoot below these numbers.
Check for these densities in several areas of your fields when the early shoots are 4 to 6 inches tall. Since some shoots begin growing later than others, stands with enough plants but slightly low shoot density may be alright, especially if the height and distribution of shoots is fairly uniform. But, if plant density is low, or shoot growth is not uniform, yields probably will decrease.
Checking your fields now will allow time for changes in your cropping plans.
Bruce Anderson
Extension Forage Specialist
Certainly your own personal needs and objectives determine whether
clear seeding or a companion crop is better for you. My personal
preference, though, is to clear seed whenever practical. When you clear
seed, alfalfa production begins much sooner, with 2 to 4 tons possible the
seeding year. Companion crops usually prevent any alfalfa harvest the
first year and often cause thinner stands. Also, yields and stands in
following years almost always are better with clear seeding than when using
a companion crop.
Did you notice that I call oats a companion crop instead of a nurse
crop? That's because companion crops like oats don't nurse new alfalfa
seedlings at all. Instead, they act like weeds, robbing alfalfa seedlings
of moisture, sunlight, and nutrients during the seeding year. Such behavior can hardly be called
nurse-like. However, companion crops can help stabilize erosive soils and provide grain and straw.
Consider your operation's needs and goals when selecting between these options. If you mainly want alfalfa, plant only alfalfa. If erosion is a problem, add 20-30 pounds of oats, but kill or cut the oats early
rather than taking grain. Likewise, if you want oats, plant only oats. Then seed alfalfa into the stubble next August.
Bruce Anderson
Choosing a herbicide strategy to deal with weeds is not always easy, given the many options that should be considered. Factoring in the economics such as herbicide costs, fuel and time, combined with biological and environmental factors, makes the job tough enough; however, when you consider that within that environment, you include weed species spectrum, soil type, organic matter, herbicide efficacy, herbicide restrictions, annual precipitation, precipitation at time of application, and the ability to make timely treatments, there’s no easy decision. After factoring in all of these variables, often there is still no perfect choice.
Corn /weed competition
All weeds are not created equal. Each weed species competes differently with corn with some species being much more competitive than others. For example, common sunflower has a competitive index of 10 and is much more competitive than lambsquarters, which has a competitive index of about 2. Understanding the differences between each species and their competitive factors can be very important in determining what weed management strategy will provide the best return on investment.
Since weeds are not created equal we should acknowledge that neither are crops. Each crop differs in its competitive ability as well. Corn is one of the most competitive row crops planted in Nebraska. The relative competitive load necessary to cause a specific yield loss quantifies the competitiveness of a crop. For corn, it would take a competitive load of about 36 per 100 ft2 to cause a 5% yield loss (100 ft2 is approximately 40 feet of row in 30-inch rows) Sunflower, however, has a competitive index of 10, therefore it would take 3.6 sunflower plants per 100 ft2 (3.6 x 10 = 36) to cause a 5% yield reduction in corn. This is assuming that the weeds emerge at the same time as the crop. Accurately calculating yield loss, especially when several species of weeds are present in the field, can be difficult. WeedSOFT, a computer aided weed management decision support tool, can be purchased from the University of Nebraska to supply this information at the click of a button. Using this type of technology allows for more accurate yield loss analysis, providing better information to make weed management decisions.
Early preplant and
preemergence weed management
Controlling weeds before they become a problem just makes good sense. As the saying goes “an ounce of prevention is worth a pound of cure” and this is true with weed control in corn. Various techniques are available and depending on individual circumstances, one may be better than the other. Producers need to determine their seasonal goals before committing to any one strategy.
Before we discuss all the strategies available, be sure to refer to Table 1 for an explanation of the terms and acronyms used with preemergent corn weed control.
Early preplant herbicide (EPP) applications 10-30 days before planting offer many advantages, especially for no-till farmers. Early preplant treatments will kill winter annuals, including henbit and mustards, and early summer annuals, including giant ragweed, common sunflower and lambsquarter. This early control can be very important, especially in a dry year, when these weeds can quickly rob precious soil moisture. An early preplant treatment also will reduce most, if not all, weed competition as the crop emerges from the soil. Although this early competition may not be the most critical with respect to yield, it can quickly reduce yield as corn enters the two-leaf stage. Another advantage is that in years with limited moisture the herbicide has a greater chance of being activated before the crop emerges. A disadvantage of the early preplant treatment is decreased longevity of the residual activity. Common sense tells you the earlier a herbicide is applied to the soil the earlier it will stop working. Postemergence programs need to be carefully evaluated before making such a decision and some knowledge of the weed history in the field will be helpful.
Preplant (PP, PPSA, PPI) is similar to early preplant as many herbicides used are the same. Treatments are typically made 0-10 days before planting. Preplant doesn’t give you the advantage of catching early weeds but at the same time it may give you the needed residual for setting the stage for a good POST treatment.
A preemergence treatment (PRE), applied after the crop is planted but before emergence, offers many of the same advantages. An additional advantage is that it allows the producer to increase the longevity of control provided by the herbicide. This works well with conventional till fields. This also provides increased management flexibility later in the season as summer annuals begin to emerge.
Table 2 lists labeled preemergence herbicides and their application timings. As always, read, understand, and follow the label supplied with each product. For further evaluation of herbicide efficacy on weeds and weed/crop competition, see the Guide For Weed Management in Nebraska (EC130), available for $3 from your local Extension Office.
Brady KapplerTips for clear seeding alfalfa
When many folks plant a new field of alfalfa, they also seed a
companion crop like oats to control weeds and erosion. Others clear seed
alfalfa alone, without a companion crop, often using herbicides to control
weeds. So which method is better?
Extension Forage Specialist
Strategies for early season weed control in corn
Warmer weather across much of the state has been tempting many producers to hook up their planters. Of course, with warm weather weeds can’t be far behind, especially the early germinators like lambsquarters, giant foxtail, velvetleaf, and sunflower.
Weed Science Educator
Alex Martin
Extension Weed Specialist
|
Results from studies on the effects of removing crop residue from the row area in no-till systems have been inconsistent in the Corn Belt. In most studies, the crop residue was removed at planting time. In Iowa, removal of residue from a six-inch band resulted in increased corn plant emergence, but only occasionally increased yield. In southern Minnesota, corn yields increased an average of five bushels per acre with row cleaning, but the benefit of row cleaning was greatest when no starter fertilizer was applied.
As part of the Nebraska Soybean and Feed Grains Profitability Project, Jerry Mulliken has conducted replicated trials on his farm in Dodge County for six years to evaluate the effect of row cleaning on corn yield following soybean. For five years, he cleaned a six-inch band 14 days before planting when pre-plant herbicide was applied. In 2003, he compared row cleaning two weeks before planting with row cleaning at planting.
Mulliken cleans the row space with a notched or tined furrow opener running just below the residue layer, while disturbing less than the top inch of soil. He estimates the added cost of row cleaning to be $3 per acre. The average gain in corn yield with row cleaning has been five bushels per acre. Mulliken conducted the trials with 4-6 gallons of 10-34-0 applied in the seed furrow to both the strips with and without row cleaning.
Row cleaning is sufficiently promising that no-till producers may want to test it by conducting replicated comparisons on one or more of their fields. In the meantime, we are conducting trials at the Rogers Memorial Farm to determine the effect of row cleaning with earlier planted milo. Combining row cleaning with another operation such as pre-plant herbicide application or planting is important to reducing costs. Row cleaning on highly erodible land can result in increased soil erosion, especially when planting up and down slopes.
Charles S. Wortmann
Nutrient Management Specialist
Warm dry conditions this spring in western Nebraska will encourage early growth and increase the need for timely moisture. Subsoil moisture in much of western Nebraska is not adequate to carry the winter wheat crop very far into the active spring growth period. Fields fallowed with herbicides, and that had crop residues, contain more soil water than conventionally fallowed fields. Growers will be dependent once again on timely precipitation this spring. Last year, Mother Nature provided excellent growing conditions for the winter wheat crop. We are unsure she will be so generous again this year.
Drew Lyon
Dryland Crops Specialist
Panhandle REC
Bob Klein
Cropping Systems Specialist
West Central REC
Lenis Nelson
Crop Variety Specialist
Watching for early season wheat diseases
|
One of the earliest diseases to occur in seedling wheat will be the soil-borne mosaic virus which is already visible in Oklahoma and Kansas. From a distance wheat fields affected by soil-borne mosaic show areas of yellow or pale green wheat. These areas often conform to low areas such as terrace channels or drainage paths. Sometimes the pattern may be generally distributed across a field.
So as to not confuse this disease with nutrient deficiency, closely examine plants in the affected areas. They are often stunted and the leaves will show a light green mosaic pattern. Losses are generally not severe unless the variety is very susceptible and the incidence of disease in the field is high. Since this is a virus, nothing can be done to control it once the crop has been planted.
For more information, see the NebGuide, Wheat Soil-borne Mosaic Disease (G74-202, revised in 2001), available from your local Cooperative Extension office.
Last fall Oklahoma reported a fairly high incidence of leaf rust, but apparently it did not overwinter well. The latest reports have leaf rust at a low incidence in Oklahoma. In Texas the incidence appears to be scattered with some areas of south Texas reporting severities of 60% on the more susceptible varieties. As of last week no leaf rust had been reported active in Kansas.
Stripe rust incidence is light across southern Texas and has not been found in either Oklahoma or Kansas. Development of both rust diseases south of Nebraska will continue to be monitored as the season progresses. If rust looks like it will be a problem, we will provide advance notice in CropWatch in sufficient time to apply a foliar fungicide.
John Watkins
Extension Plant Pathologist
Winter annual weeds typically germinate in the fall and then produce seed in the spring to
early summer. As annuals their job is to produce seed so the species can survive another
year. Since weed seeds can last three or more years in the soil, control measures will need
to be extended over several years.
If you have warm season grasses in your pasture, there are several control options.
Glyphosate is available until “greenup” begins. Use 16 to 24 ounces if weeds are small or
if there are only winter annual grasses. If weeds are bigger or you have tough broadleaves
like henbit or marestail, add 1 pint of 2,4-D ester (4L) to the 16 to 24 ounces of
glyphosate. Another option for warm season pasture is a prescribed burn. If the pasture
has not been overgrazed and there is enough fuel, a prescribed burn will do a great job of
controlling winter annuals and stimulating warm season grasses.
For cool season pastures or for mixed pastures of cool and warm season grasses, neither
glyphosate or a prescribed burn are options. Broadleaves can be controlled by using 1-1.5
pints of 2,4-D ester (4L) plus 0.5 pint of dicamba. Henbit control will not be as high as
other broadleaf winter annuals, but it is about the best you can expect with herbicides in a
cool season pasture. If you have winter annual grasses, herbicide treatments will not
provide sufficient control; however, there are management options such as grazing early
and grazing heavy. Of course there is a fine line between heavy grazing and over grazing.
You just need to keep the winter annual grasses from going to seed as much as possible.
Once the winter annual grasses are knocked down and the pasture grass is greening up,
stop grazing the pasture for a month to six weeks to let the desirable pasture grasses
recover and begin to develop.
Remember, pasture weeds are symptoms of management issues. Overgrazing in the fall
can provide a great opportunity for winter annuals to germinate. Just a little 2,4-D or
dicamba in the fall can provide good control of winter annual broadleaves. Whether
applied in the spring or fall, herbicides always work better when weeds are small and
actively growing.
Controlling weeds in pastures is not a one year job, but rather will take several years of
diligent control followed by annual maintenance to keep pastures in good condition.
Brady Kappler
Right now is a bit too early to burn warm-season grasses. Burning now will open up the
ground to a weed invasion and soil erosion soil and allow valuable moisture to evaporate. The
best time to burn warm-season grasses is when they just start to grow, usually in late April to
early May. Burning then will result in rapid greenup and thickening of desirable
warm-season plants.
When planning and conducting a burn, be sure to do it safely. Always obtain a burn permit
from the appropriate local authorities. Never burn unless weather conditions, topography, and other factors
enable you to control the fire and always include someone experienced in prescribed burning as part of your burning crew.
Bruce Anderson
Steve Pritchard, Extension Educator in Boone and Nance counties: There’s good topsoil moisture, but limited subsoil moisture. Cutworms are a major problem in many alfalfa fields, as evidenced by delayed greenup. Extensive spraying is underway. Producers are starting to do some field work - fertilizer applications and disking. Many producers are preparing fields for seeding alfalfa, oats and other small grains.
Karen DeBoer, Extension Educator in Cheyene County: The main activity is preparing ground for planting crops this spring. The wheat is greening up and in some places, wheat that was planted later does not look as good as the earlier planted wheat. Moisture is needed in all areas of the southern Panhandle.
Duane Lienemann, Extension Educator in Clay and Webster counties: We’re seeing quite a few army cutworms in wheat, especially in southern Webster County from Guide Rock to Red Cloud with some reported in the center of the county. We also are finding some in alfalfa. Wheat levels have been above the threshold in some areas and fields have been treated; most alfalfa levels have been below the threshold.
This week areas of the county received 0.5 to 1.5 inches of rain, helping the winter wheat to quickly add density and fill in between rows. The moisture also is helping June grass, cheatgrass and other annual bromes get a good start in pastures. Some producers are planning to use flash or rotational grazing to control these early invaders.
As we enter what would be our fourth season of drought, producers are planning accordingly. There has been some talk of overseeding older alfalfa stands with Italian rye grass so it could be grazed, if necessary, or hayed. This would help provide some rest for pastures.
While some producers applied fertilizer just before the rains, others are delaying application due to current high prices and a concern about the potential for drought. If dry conditions prevail, they don’t want to incur an unnecessary expense and create the potential for high nitrates in cornstalks they might need to graze later.
We’ve seen an increase in the number of wheat acres planted. Winter annuals, such as pennycress, are visible in wheat and alfalfa and should be treated.
Some no-till farmers, especially on irrigated acres, are looking at high tonnage levels of residue and hitting the ridges with roller and flail choppers to break down residue.
Nebraska corn growers expect to plant 8.0 million acres, down 1% from last year. Of these acres, 41% is expected to be planted to insect resistant (Bt) varieties, 15% to herbicide resistant varieties and 8% to stacked gene varieties, compared to 36%, 11% and 5%, respectively a year ago.
Expected soybean plantings of 4.65 million acres in 2004 would be the third highest on record, up 2% from last year, but 6% below the 2001 record high. Of these acres, 89% are expected to be planted to herbicide resistant varieties, up from 86%.
Sorghum growers expect to plant 550,000 acres, 17% less than in 2003, but 22% more than in 2002. Hay acreage for harvest, at 3.1 million, would be down 2% from last year. Oat planting intentions, at 155,000 acres, are down 30% from 2003. Dry edible bean producers intend to plant 145,000 acres, down 6% from last year. Sugar beet plantings of 45,000 acres would be down slightly from 2003, while sunflower intentions, at 55,000 acres, are down 17%.
Resistance Management for YieldGard RootwormTM Bt Corn (NF04-594)
2004 Beef Report Summaries (G78-425)
2004 Nebraska Swine Report (EC04-219).
Drinking Water Treatment: An Overview (EC03-703)
Bovine Spongiform Encephalopathy in the United States (NF01-455)
Winter annual weed control in pastures
Winter annual weeds are one of the weed problems that many people, who use pastures
for livestock, tend to overlook. Weeds like downy brome, wild oats, pennycress, henbit,
and marestail pop up in pastures all over the state. Many people feel that since they
flower early and are gone by prime grazing season, they are not a problem; however, as
these weeds increase, they crowd out the desirable grasses and restrict the development of
quality pastures.
Weed Science Educator
Use care when burning CRP
Prescribed burning CRP grasslands can improve stands, prepare for interseeding, control
weeds and trees, enhance wildlife habitat, and improve forage quality. But it must be done
safely. Fire is a useful tool in managing CRP or other fields that have become overgrown with dead plant material. This mulch can smother plants and new seedlings. Fire removes this mulch,
enabling stands to thicken, and can reduce the invasion of woody plants, weeds, or cool-season
grasses into warm-season grasses. These less desirable plants are injured or killed by
a well-timed burn.
Extension Forage Specialist
Field reports
Paul Hay, Extension Educator in Gage County: Recent rains in southeast Nebraska have helped activate the wheat and alfalfa herbicides as well as dry fertilizers that had been applied. Monsanto and Pioneer have agreed to fund 50 soybean cyst nematode samples collected by Extension personnel in the Missouri River Valley and river bottom and nearby creek valleys from Rulo to Peru. We’ve collected 14 so far and will report results in CropWatch as they become available.USDA reports prospective plantings
Nebraska producers expect to increase acreage planted to soybeans and winter wheat (‘03 planting) while decreasing corn, hay, sorghum, oat, dry edible bean, sunflower, and sugar beet acreage, according to a March 31 report from USDA Nebraska Agricultural Statistics Service.Hot off the press
The following new or newly revised publications are available at local Cooperative Extension offices or on the Web.
 |
About Crop Watch |
Agricultural News |
Events |
Archives |
Markets Ag Links | Weather | Photos | Search Lisa Jasa, Crop Watch Editor | Publications | IANR |
 | ||
| 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 | ||
| The University of Nebraska-Lincoln does not discriminate on the basis of gender, age, disability, race, color, religion, marital status, veteran's status, national or ethnic origin, or sexual orientation. | ||
