Aug. 22, 2003

Corn condition continued to decline and rated 12% very poor, 13% poor, 24% fair, 36% good, and 15% excellent, above last year but slightly below average, reported USDA's Nebraska Agricultural Statistics Service.

Lessons learned with Clearfield wheat in 2003

Wheat cultivars with this gene may be treated with Beyond herbicide with minimal risk of crop injury. Beyond will seriously injure or kill winter wheat cultivars without the tolerance gene. In field research in western Nebraska and throughout the western winter wheat belt, CPSW provided excellent (95%+) control of jointed goatgrass and downy brome when weeds were treated with 4 ounces of product per acre in the fall or early spring. Fair to good (80%+) control of feral rye required an early fall application with 5 ounces of product per acre. It provided optimum control of feral rye with little wheat injury when Beyond was applied before rye plants had produced a tiller and wheat had at least three leaves emerged. Some wheat growers in the Nebraska Panhandle reported inconsistent control of feral rye with Beyond herbicide in the 2002-2003 crop. Cold weather conditions within a few days of application may help explain some of the inconsistent performance. Although feral rye control with Beyond is not at the same level as with the other winter annual grasses, it is still the best selective control method available for feral rye at this time. Each grower will have to decide for themselves as to whether 80-85% control of feral rye is worth the $20+ per acre treatment cost.

Management tips Aug. 22-Sept. 5 Treat wheat seed with a seed treatment fungicide before planting. In a dry year this may help reduce the risk of crown and root rot brought on by drought stress. It is also good insurance against common bunt and loose smut. To reduce the incidence of winter kill and crown rots, make sure the drill is running "tail down" when seeding wheat. By putting extra weight and downpressure on the press wheels, seed-to-soil contact is improved and the seedbed is firmed up. A firm seedbed heaves less with freeze/thaw and wetting/drying, reducing damage to the roots and crowns. The firm seedbed is less likely to dry out compared to a fluffy one, further reducing damage to the seedling wheat.

Among weed control specialists, the biggest concern with the Clearfield production system is the potential for developing herbicide-resistant weeds. Because Beyond provides such excellent control of jointed goatgrass and downy brome, it will exert a tremendous selection pressure for resistance. Beyond belongs to a class of herbicides known as ALS-inhibitors. Other herbicides in this class, such as Glean and Pursuit, have a history of quickly selecting for resistance in weed populations. Examples include ALS-resistant kochia, prickly lettuce, and pigweed. In the case of jointed goatgrass, resistance also may occur through pollen transfer. Jointed goatgrass and wheat share a common genome, the D genome, acquired from a common ancestor. Research has shown that there is a slight chance of moving the resistance gene from a Clearfield cultivar to jointed goatgrass within several generations. Without adequate safeguards, it is likely that weeds resistant to Beyond will be common in just a few years.

In order to delay the onset of herbicide resistance, fields treated with Beyond should not be treated with another ALS-inhibitor such as Ally or Peak. If additional weed control is needed, for example to control warm season broadleaf weeds like kochia or pigweed, use herbicides with a different mode-of-action. Herbicides containing 2,4-D or dicamba would be good choices for additional weed control.

The BASF Clearfield stewardship program for wheat requires the use of only certified seed in order to prevent the pollen flow required to produce a jointed goatgrass plant with resistance to Beyond. Growers will not be allowed to save back any grain for seed. The stewardship program also does not allow for using CPSW more than twice in a four-year period. University researchers in the Great Plains are concerned that this requirement is not adequate to sufficiently delay the onset of herbicide-resistant weeds. They recommend that the CPSW not be used more than once every three years. This would prevent growers in the winter wheat-fallow rotation from using the system every time they grow wheat.

Another concern with this system is the high cost of the herbicide. The herbicide costs about $4 per ounce or $16 per acre for a 4-ounce per acre rate.

In northeast Nebraska, populations jumped during the week of August 10-16. We have been "treated" to an amazing example of the reproductive potential of these aphids. Some growers have opted to spray their fields, while some have decided not to. Talking to quite a few consultants, growers and dealers has led us to conclude that populations had not been very high until that week. Soybean aphids are being reported in other areas of the state but are expected to cause less damage where plant growth is more advanced.

At this point, many growers in northeastern Nebraska are considering the potential for damage and whether treatment is warranted.

Heavy rainfalls may wash aphids off the plant, however rain has been spotty. Several fields scouted on Monday and Tuesday showed a huge leap in lady beetle and parasitoid numbers and we believe that many aphid populations are now stabilizing or even declining. Looking for predators, especially lady beetles, should be a key factor in deciding whether to treat. Fields where the aphid populations appeared to be decreasing had one or more lady beetles per foot of row visible on the tops of the soybean plant.

This week's hot weather may have provided another natural control method by reducing the aphids' reproductive potential. Aphids prefer moderate temperatures for the most rapid reproduction. The looming question now is "When will aphids leave the fields?," and unfortunately we don't have a sure answer.

The Catch-22 is that the longer you wait to treat, the less likely the return on investment as the beans continue to mature and the aphids get nearer the time where they will leave the fields to search for overwintering sites.With most beans currently in the R5 stage we feel that at least 400 or more aphids per plant would be necessary to get an economic return from treating (this is assuming that populations are still increasing in that particular field). Fields that are delayed in maturity (less than R5) may benefit more from treating as the yield potential may be affected more.

Soybean aphids represent a new pest that is behaving in a way that has not been seen before. We can only make educated guesses, put out test plots, and make careful observations that will help in future decision-making.

Previous research and a sample taken recently from soybean fields on UNL's East Campus indicate that these are greenhouse whiteflies, Trialeurodes vaporariorum.

Whiteflies are sucking insects that feed on plant juices in both the immature and adult stages. The adult stage is about 1/16th inch long, with four whitish wings and a yellowish body. The wings are held roof-like over the body and are more or less parallel to the leaf surface. The adults are easily disturbed and often fly up as you walk through a field. The nymphs feed on the undersides of leaves. They are flattened and look like scale insects.

There are no published economic thresholds for greenhouse whiteflies in soybeans, and from all indications, the soybean aphid is probably the greater concern in Nebraska soybeans.

Visit UNL exhibits, talk with specialists

The Institute of Agriculture and Natural Resources (IANR) will offer more than 20 exhibits and displays as well as five live issue-based Market Journal broadcasts. Some of the displays will be interactive, include short demonstrations, or offer educational materials to provide more information on a specific topic. A selection of free Extension publications and CropWatch materials also will be available.

Exhibits related to crop production will include: Insect and disease management in crops; Precision agriculture: High technology down on the farm; Marketing tips for crops and livestock; Drilling for Nebraska's precious water; Quality seed - your crop's foundation; Farm financial analysis; Nebraska's research in water quality; New designs for pesticide labels; Conserving Nebraska's natural resources; Integrated crop management; and CropWatch/Market Journal.

Other exhibits will target rural issues, livestock production and opportunities at UNL. They will include: Building strong families during hardships; Educational opportunities at UNL: an investment for Nebraska; Nebraska livestock production; Livestock biosecurity; Cost share funds for livestock producers; LEAD: developing Nebraska's leaders; Food preservation through irradiation; the International Quilt Study Center; and Discover 4-H, Discover You.

If you or someone in your family is interested in pursuing educational opportunities at UNL, representatives from the College of Agricultural Sciences and Natural Resources and the Nebraska College of Technical Agriculture (Curtis) will be available to discuss their programs.

Soybean and sorghum also have declined during the last six weeks with only 34% of the soybean crop and 15% of the sorghum crop now rated good to excellent. Rains Aug. 18-20 in the eastern third of the state may bring some relief.

The situation in Nebraska is similar to that in parts of Kansas, Iowa, Missouri, Minnesota, Illinois, and Wisconsin. The National Agricultural Statistic Service reported that nationally corn and soybean condition declined for the fifth consecutive week. Reports from the top 10 producing states indicated that the corn crop had dropped to 60% good to excellent, down from 74% on July 13. Soybeans rated 56% good to excellent, down from 70% on July 13.

A review of state reports indicated that most fields in the northwest corner of Missouri were expected to produce little if any grain. Iowa fields were rapidly deteriorating on the upper halves of sloped fields and soybean aphid infestations were increasing to the point that aerial spraying was required. Minnesota and Illinois fields were showing signs of moisture stress. Corn and soybeans in Wisconsin were exhibiting severe stress, particularly in the sandier soils.

Ratings for Nebraska's irrigated corn crop were considerably better than the dryland crop, with 77% of the crop rated good to excellent. Limited water to no available water were reported across the Panhandle, southwest, south central, and southeast Nebraska. Soil moisture was virtually non-existent across much of the state as of August 17. Almost every station within the High Plains Climate Center's soil moisture monitoring network indicated little, if any moisture below 12 inches. Any moisture in the top 12 inches resulted from scattered thunderstorms in the last 7-10 days.

During the next two weeks, warm temperatures are projected to continue, but 100+ temperatures appear doubtful. Drier than normal conditions are projected until Labor Day weekend when a robust storm system is forecast. Otherwise, any precipitation is expected to be widely scattered, with the best likelihood occurring across the western third of the state as a result of monsoonal moisture and weak upslope flow. Unfortunately, for many dryland farmers, the recent moisture and predicted late August precipitation may be a little too late.

Everywhere you look, dryland alfalfa has stopped growing. Many of us have alfalfa fields with plants six to twelve inches tall getting more and more purple by the day. With little relief in sight, what should we do -- hay it, shred it, graze it, or just leave it?

First the good news: while it stays dry you can do whatever you feel like doing and you aren't likely to hurt your alfalfa. The bad news is that if it stays dry you won't do it much good either. So my recommendation is to use it or lose it.

As your alfalfa continues in a dormant state, it will slowly lose feed value and tonnage due to continued maturation as well as leaf loss from insect feeding, diseases, and old age.

A yield of at least one-half ton per acre probably would be needed to justify the fuel, labor, and other expenses involved with harvesting hay. Grazing might be relatively cheap in terms of out-of-pocket costs if you already have portable electric fence and don't need to transport cattle or water. Dry, bloomed-out alfalfa has a pretty low risk for bloat. It's not foolproof, but common sense animal husbandry should enable you to graze it safely.

If you can't hay or graze, it's probably best to just leave it alone. Shredding will give you a cleaner, higher quality hay once your alfalfa receives enough rain for regrowth and it probably will start regrowing just a bit faster. In most cases, however, it's not worth it when you consider the cost and time involved in shredding.

For tilled seedbeds (usually fallow) where the seed can be placed in firm soil at the correct seeding depth for the winter wheat variety, the crop producer's best option is probably to go ahead and seed even if the soil is dry and the wheat seed will not germinate immediately. Wheat requires 41% seed moisture for germination which is 9% more than corn (32%) but 10% less than soybean (51%).

The maximum depth a winter wheat variety with a short length coleoptile can be planted is 2 inches in a silt loam soil. In extremely fine-textured soil with a high clay content, reduce planting depth by up to ˝ inch. In coarse-textured soils with lots of sand, increase planting depth up to ˝ inch. For winter wheat varieties with medium length coleoptiles these seeding depths can be increased by ˝ inch; for varieties with long coleoptiles seeding depth can be up to 3 inches with the adjustment for the soil texture. Warmer soil tends to shorten the coleoptile length. The coleoptile penetrates the soil and results in seedling emergence. If the seed is planted too deep, beyond the elongation of the coleoptile, seedlings cannot emerge and the result will be a poor stand.

If the seedbed is loose and the seed would be placed in loose soil, delay seeding until there is moisture is received to firm the seedbed. Seed placed in a loose seedbed is one of the leading causes of winter injury - root and crown rot.

Before beginning to plant, make sure openers and disks are not worn. For hoe drills, good quality spear point or eagle back openers usually improve performance. Hoe drills, especially those with wider row spacing, are able to plant the seed deeper because they can build a ridge and plant in the furrow. Slow ground speed so adjacent rows are not covered with soil. The seeding depth then becomes the soil cover over the seed. If the seedbed was not tilled too deep, it usually is possible, with the hoe drill, to place the seed in firm, moist soil. Deep tillage or applying anhydrous ammonia with knives can dry out the soil, so it could be impossible to place the seed in firm moist soil even with a hoe drill.

As with everything, there are drawbacks to the hoe drill. The biggest is that if a hard rain occurs, the ridges will be destroyed and the seed, or developing plant, will end up under too much soil cover.

Seeding with a disc drill in a loose seedbed almost guarantees disaster and should probably be delayed until there is moisture.

For continuous cropping do not till. If you do till, the seedbed will dry out to the depth of tillage. The soil should be firm after soybeans are harvested. If planting winter wheat this year, make sure the drill is running lower in back than normal. Transfer more drill weight to the back of the drill and add extra weight to the drill. This will allow for penetration into dry, hard soil, forcing the seed into the soil and insuring seed to soil contact. Also, don't plant wheat too shallow. When using disc drills, plant at a depth of 2 inches.

Do not seed winter wheat much earlier than the suggested seeding date for your area. Early seeding leads to problems with diseases such as wheat streak mosaic and insects such as the Hessian fly.

As with all these rules there are exceptions. The biggest exception is to make sure you seed by the required date for crop insurance in your area.

If you seed more than a week to 10 days after the recommended seeding date, use row-applied starter fertilizer. This is important even if your soil tests high in phosphorus. Also, since less tillering occurs with later plantings, it is usually beneficial to increase seeding rates. Plan to seed about 1.4 million seeds per acre dryland and 2.0 million seeds per acre under irrigated conditions. With late seedings, narrow rows are preferred -- 7.5 inches for dryland and 6 inches or less for irrigated.

However, as the filling rate increases, it takes more tractor packing weight to avoid trapping undesirable amounts of air inside the silage pile. If bunkers are filled faster than they can be packed well, many desirable nutrients will be lost due to excessive respiration, heating, fermentation, and mold.

So, how much tractor weight is needed? Research shows that if you multiply the number of tons of silage being filled per hour by 800, this will equal the total weight needed by packing vehicles to do a good job of packing. For example, if you are filling a silo at 40 tons per hour, multiply 40 by 800 to get 32,000. This represents the pounds of packing vehicle needed. This might be accomplished with one bulldozer or two medium weight tractors.

When you pack, spread out each load so you have less than six inches of fresh, unpacked silage under the packing wheels. This also will help reduce air pockets.

Inoculating silage

To make good silage, sometimes inoculants are needed to improve fermentation. There is no clear-cut, consistent way to predict when inoculants will be most useful. Silage fermentation is just too complex.

Inoculants primarily reduce storage losses. Fermentation starts and ends quicker with inoculated silage so more silage remains for feeding. And some inoculants can improve feeding value, although results are a bit inconsistent.

Inoculants do consistently improve wet silage, especially sorghum silage. If you start chopping a little early to prevent silage from being too dry at the end, inoculants should help. When you begin chopping, grab a handful and squeeze it tightly in your fist. If free juice squeezes from the forage, it is wet enough to benefit from use of an inoculant.

In the past, inoculants rarely improved properly made corn silage - silage at the right moisture, chopped fine, packed well, and sealed tight. Nor did they improve dry silage. However, recently developed inoculants with more effective strains of fermentation bacteria are producing slightly better quality silage.

If you use an inoculant, make sure it contains live bacteria and provides at least 100,000 colony-forming units per gram of wet forage when applied at the recommended rate. You need plenty of live bacteria for the inoculant to work well.

The Aug. 26-27 event will offer realistic solutions for producing higher crop yields while keeping production costs economical, said Keith Glewen, extension educator in Saunders County.

The benefits for agricultural professionals from attending Solution Days 2003 will be well worth the time invested, said Norm Husa, chairman of the Nebraska Soybean Board. Sound advice from expert presenters coupled with up-close plot tours will provide an excellent learning opportunity, he said.

Topics will include weed resistance management, components of corn and soybean yield, water management and use, seed treatments, refuge acres, and resistance management.

Presenters include industry consultants and University of Nebraska specialists. The program is from 9 a.m. to 2:30 p.m. each day with in-field presentations.

To reach the Syngenta farm near Goehner, take exit 373 on Interstate 80 and go one-fourth mile south.

Meetings will be held Sept. 4 near Mead; Sept. 10 near North Platte; and Sept. 17 at Bridgeport. Morning programs start at 10:30 and afternoon programs begin with lunch at noon and end at 3:30 p.m.

The registration fee is $30 for the full day and $20 for the afternoon program. Space is limited for the morning program. Lunch will be provided to both morning and afternoon participants. Please pre-register by calling the Extension Office in the host county at least two days before the event.

Oat harvest for grain was nearly complete with 97% combined, behind last year and average. Sorghum condition declined and rated 15% very poor, 29% poor, 41% fair, 15% good, and 0% excellent, above last year but below average. Seventy-two percent of the acreage was headed, behind last year at 80% and average at 85%. Heads were turning color on 9% of the acreage, behind last year at 22% and average at 14%.

Dry bean condition rated 4% very poor, 8% poor, 27% fair, 53% good, and 8% excellent. Eighty-one percent had set pods, behind last year at 90% but ahead of average at 79%. Plants were showing color on 10% of the acreage, behind last year at 16% and average at 12%.

Alfalfa condition declined and rated 15% very poor, 27% poor, 35% fair, 21% good, and 2% excellent, above last year but below average. Third cutting activities were 61% harvested, behind last year at 71% but ahead of average at 59%. The hot, dry weather continued to indicate little or no third cutting for many dryland producers.

Soybeans are in the critical stage for seed fill and are just staying green. They will suffer if the dry weather continues. Alfalfa third cutting is coming off, regrowth will be marginal and there will not be another cutting unless it happens to rain. Pastures are done for those who do not rotate or have intensive grazing systems set up. Producers needing additional feed could use their corn for silage; however, most farmers will probably take what grain they can get from the field. Regarding insects, all soybean fields have aphids and some grassy areas have grasshoppers.

Noel Mues, Extension Educator in Furnas County: After receiving timely rains this spring, it has turned extremely hot and dry during July and August. Crop conditions declined as the month progressed. Surface water irrigators will be far short of required water as we head into the final stages of the growing season. Livestock producers will need to seek alternative feed sources as pastures dry up. With the low water levels in area lakes it is obvious that the drought still has a strangle hold on much of the central and western United States. On the bright side, an excellent wheat harvest was reported by most area producers with yields in the 50’s and 60’s common throughout the area.

Ron Seymour, Extension Educator in Adams County: Irrigated corn is in excellent condition and in the late dough to early dent stages. Due to drought stress, dryland corn is in poor condition and only about 10% of the crop will have any significant yield. Soybeans are maturing, with the irrigated crop in excellent condition. Soybean aphids have been identified in a number of fields, but not enough were found to initiate insecticide applications. Recent rainfall has helped some of the grain sorghum fields but the crop is still under significant moisture stress in a number of areas.

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