Soybean Aphid Update

Yes, it appears the soybean aphids are finally going to up and leave area soybean fields. In untreated plots at the Haskell Ag lab, numbers have dropped from over 1000 per plant to 300, with the combination of predators, parasitoids and maturing beans finally making a significant dent in populations. We are in great need of numbers, yield data, and other information to help us understand the impact of soybean aphids in area fields. For example, we do not know how harmful the aphids are in irrigated fields, where moisture shortages are not a concern. Not knowing the true impact of aphids in irrigated fields could cause significant overtreating. Ideally we would need aphid numbers at the time of treatment, date of treatment, variety, irrigated or dryland, and yield data from untreated and treated areas. We will of course get data from our plots at the Haskell Ag lab, but the more data we receive the better our knowledge will be in the future. (KJ)

Don't Stop Irrigating Soybeans Too Soon This Season

Continuing drought and lagging crop development in several areas of Nebraska make it especially important for soybean growers to carefully plan their final irrigations and not stop watering too soon. Final irrigations need to be based on soybean plant needs and not dates on the calendar, especially for crops planted late.

While irrigation has ended for corn, soybean irrigation may still be needed for the next couple of weeks in the eastern two-thirds of the state. Peak moisture needs of soybeans usually follow those of corn by about three weeks. Most of the soybean crop's water needs are during pod fill. Irrigation will help with pod fill, but not add any more pods.

Producers often are surprised at how many inches of water are needed to finish out the soybean crop. Timing also is important. Shutting off too early reduces bean size, sometimes greatly reducing yield. Irrigating later than necessary reduces room for storing off-season precipitation, increases the potential for leaching nitrogen and adds to production costs. Finding a balance between the two requires knowing how much water is available in the root zone and how much more water the crop will need to reach maturity. Water requirements to reach maturity depend on the crop growth stage. It's especially important to note that even though soybeans may appear to be shutting down when they start turning yellow, they still need about two inches of water to reach maturity. The last irrigation usually can be applied two to four weeks before soybeans are mature, depending on the water-holding capacity of the soil. This will leave room for storing off-season precipitation. For more information on predicting final irrigations, including determining soil moisture, consult Nebraska Cooperative Extension NebGuide G82-602-A, Predicting the Last Irrigation for Corn, Grain Sorghum and Soybeans, available online at http://ianrpubs.unl.edu/irrigation/g602.htm , or G84-690-A, Estimating Soil Moisture by Appearance and Feel, available online at http://ianrpubs.unl.edu/irrigation/g690.htm. Both are also available at local extension offices.

More details about scheduling the last irrigation, including a worksheet to help determine last irrigation, are available in Crop Watch, Extension's crop production newsletter, on the Web at http://cropwatch.unl.edu/archives/2004/crop04-20.htm#irrigation. (BK)

Helping Cattle Adapt To And Cope With Winter Stress

Cattle producers that are under-prepared for cold, wet fall and winter weather often see decreased feed efficiencies and fewer cattle feeding profits. For every animal that dies as a result of climatic effects, the overall economic loss to the feedyard can approach several thousand dollars. This includes the dead animal, plus the loss of performance of other cattle in the feedlot. Rarely are environmental conditions perfect for feeding cattle, however, differences between a good winter for feeding cattle and a bad winter for feeding cattle can be small. As opposed to a winter that is just cold or snowy, the combination of climatic factors and how often environmental conditions change are of greater concern.

In general, winters that result in significant stress in cattle fall into two categories: 1. Winters in which we have above normal snow and snowstorms are particularly stressful if there are three to five significant snow events during the season, and periods in which snowstorms occur at five to ten day intervals. Under these conditions, which are particularly stressful on animals, temperatures often cycle between slightly above normal to well below normal, with sudden drops in temperature accompanied by high winds and blizzard conditions. 2. Winters that usually cause even greater problems for cattle feeders are those in which we have early and above normal moisture. These winters can even be accompanied by normal to above normal temperatures. Above normal late fall precipitation frequently results in muddy lot conditions. If moisture continues throughout the winter, feedlot surfaces and cattle never get dry, resulting in poor cattle performance and compromised immunity in young cattle into spring.

In the early 1980's and 1990's we experienced very wet winters, while during the winter of 1996-97, the Northern Plains suffered from frequent snowstorms and high winds. Also, in 2000-01, many cattle feeders had to contend with muddy pens from late fall into spring, as a result of an above normal moisture pattern and limited freezing of feedlot surfaces. While producers can't eliminate cold stress, using bedding, providing wind protection, and increasing pen space can help cattle adapt to cold conditions.

Providing a small amount of bedding for cattle during very cold and/or wet days can make a big improvement in gain and feed efficiency. When used properly, bedding can increase returns $10-15/head, above bedding costs, during bad winters. If you're going to use bedding, put it in the pen after you feed, not before. Regardless of season, dry areas are always needed to allow animals to spread out and lay down. Dry feedlot surfaces will allow cattle to stay dry and the hair coat to insulate the cattle against cold conditions. The more you concentrate the animals, the more problems you will have if wet weather persists. Under wet conditions, pen space requirements need to be doubled from ~200 to 400 ft 2 of space per animal. Also, providing windbreaks for newly received cattle will help get new cattle on feed and other cattle to stay on feed. Cattle that are within 45 days of harvest are very susceptible to going off-feed under both heat and cold stress and can also benefit from shelterbelts. Cattle that are to be finished in January and February will generally benefit from being fed in pens with wind protection. Wind protection is less important for cattle that have been accustomed to feedlot conditions, eating well and finished in warmer months of the year. Dr. Terry Mader, University of Nebraska Beef Cattle Specialist