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Agro-Connect ask the expert archive

Agronomy experts from university and industry sources respond to common questions from readers.

A quick glance at your field probably won't give you the information you need to decide whether to replant soybeans this year because you're likely to underestimate your existing plant population. Before you act, you should think about any factors that caused stand reduction, the percentage of population lost, and the costs of replanting. Several university experts offer advice including an interactive tool that could help you decide.

The first thing to know about maximizing soybean yields is that the two biggest profit makers are planting date and row spacing. That probably doesn't surprise many farmers. Two other very profitable practices: fungicide seed treatments and inoculation, says Ohio State University Extension agronomist Jim Beuerlein.

Farmers who do their own spraying have had lots of experience choosing nozzles. However, most of that experience has been with choosing nozzles for herbicides, not fungicides. "Fungicides will be a new experience for most soybean growers throughout the Corn Belt," says Greg Shaner, a Purdue University Extension plant pathologist. Here's help:

Nitrogen costs are high this spring, a situation that has many farmers looking for ways to apply only the nitrogen their crops really need as a way to maximize the economic benefit. A preplant N test could help you answer the question of how much you need.

Many soybean growers are wondering whether it would be a good idea to save application costs by tank mixing rust-controlling fungicides with herbicides this growing season. The answer is no, for at least three reasons: improper timing, drift, and labeling precautions, say University of Wisconsin Weed Scientist Chris Boerboom and Plant Pathologist Craig Grau.

Attacking winter annuals and simple perennials and biennials in the fall, rather than waiting until spring, is the most effective way to control the weeds, says Jeff Stachler, Extension Weed Specialist, Ohio State University. You will get a better kill with a fall program.

Timing is critical for corn growers, because the payoff from your corn crop is right around the corner. Harvest timing is primarily determined by moisture, says Dave Welch, district agronomist for Mycogen Seeds. Yet, timing harvest is different for every farm, based upon the farm's grain handling capabilities. Learn some factors that can make a difference in whether to harvest early, and get a rule of thumb on how to to know if stalk rot is serious enough to balance out the cost of harvesting higher moisture grain.

With growers getting the corn crop in the ground early this year, there is reason to be optimistic about this year's yield, says Les Hartwig, district agronomist for Mycogen Seeds Due to cool and wet weather, initial potential for a record corn crop has decreased. Still, corn will grow in cooler temps. Learn how temperature affects corn growth.

Several different species of weeds can cause problems for corn growers and they vary according to geography, says John Long, district agronomist for Mycogen Seeds. Know your situation before making a treatment and look at your fields to see what weeds are present, he says. Use an integrated pest management approach for the specific weed issues you find. Try to choose the product with the best potential on the weeds you have - doing so can save several dollars per acre.

Don't make a final assessment on the extent of damage and stand loss too quickly, says Peter Thomison, crop scientist with Ohio State University Extension. Replant decisions should be based on strong evidence that the returns to replanting will not only cover replant costs but also net enough to make it worth the effort, he says. Thomison offers some advice and tools to help you decide if replanting will pencil out in your favor.

The task of choosing a guidance system can be challenging and overwhelming because different brands offer different features," says Matthew Sullivan, precision ag expert from Ohio State University. "Buyers need to decide what their needs are and then choose a guidance system that matches their farming situation." Sullivan offers eleven things you should know before you buy.

Q. How important is seed placement when it comes to yields? A. Improper seed placement caused by a poorly maintained planter can result in yield losses of up to 20%, says Stephen Smith, agronomy services manager for Mycogen Seeds. Smith says there are a few steps you should take before your planter rolls to make sure maximize the benefits of proper seed placement. Plus he offers a rule of thumb to help you pick your optimal planting speed.

Killing grasses and broadleaf weeds with just one application is popular among growers because it can eliminate overall expenses and save time, says Bruce Maddy, customer agronomist for Dow AgroSciences. Single-pass, soil-applied herbicide programs can work in corn - so long as the proper conditions exist, he says. Here are some factors to consider to decide if a one-pass application will achieve effective weed control without compromising yield and profit.

One of the basic principles taught in crop clinics is that postemergence herbicides are more effective on small weeds than large weeds, says Bob Hartzler, Extension weed scientist with Iowa State University. According to this rule, a herbicide applied to a two-inch weeds will provide better control than a herbicide applied to five-inch weeds. Unfortunately, life isn't as simple as we'd like, and many other factors can be as important in determining how well a herbicide kills weeds as weed size, he says.

How can you get started strip-tilling? Like any farm operation, attention to details helps to ensure success, says Tony Vyn, Purdue Cooperative Extension. "My first suggestion for someone who is new to the practice is don't start too early in the fall. It's tempting to start immediately after the combine leaves the field, but doing so can make it hard to maintain adequate berm height and soil looseness the following spring at planting time," he says.

Air temperature at the time of a foliar herbicide application can have a dramatic impact on the level of weed control achieved, says Bryan Young, Southern Illinois University. The exact response of a weed to a herbicide applied under cool conditions is difficult to predict but can include: no control; reduced control; slower herbicide activity but no change in final control; or complete control. Cool air temperatures tend to have a greater impact on weed control for systemic herbicides than for non-systemic herbicides, he says.

Do you have a question about an agronomy topic? Email We'll send some of the most common questions to professionals in the industry and see what they say. Look for answers in upcoming Agro-Connect Ask the Experts columns.

Agronomy experts from university and industry sources respond to common questions from readers.

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