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Corn+Soybean Digest

A Front-Row View

Don't let crop scouting slip down your priority list. Truth is, with the plethora of resources available at your fingertips, scouting is probably one of the easiest things you can do. It can provide the most payback in identifying potential problems before they reach economic thresholds.

To get a first-hand view of the ins and outs of crop scouting, Corn & Soybean Digest spent a day with an expert in the field. Krista Hamilton is pest survey coordinator for the Wisconsin Department of Agriculture, Trade and Consumer Protection. She surveys agricultural fields to determine crop insect levels, identify potential problems (new pests and diseases moving into the state) and provide producers weekly summaries of pest trends in various areas.

She's been in a lot of fields throughout the state during her 10 years on the job, so she can give a unique perspective on how crop scouting can be integrated into a producer's activities, how easy a program can be to implement and where to go for additional information.

Her job is part investigator, part analyst and part historian. Her routine is to scout fields during key insect life stages to assess population levels. As an investigator, she uses this data to determine if insect infestations are likely to rise above economic thresholds. As a historian, she adds her information to a database that stretches back more than 50 years, giving researchers information on past insect population levels.

“I think producers are hesitant to scout because they don't know where to start,” Hamilton says. “Some think scouting will require too much time, while others are unsure of what they are looking for, or if they can accurately identify what they find.”

In many cases, scouting a single field may take no more than 15 minutes. The frequency will depend on pressure, conditions and time. “Most states have pest bulletins that indicate the key times to scout, and what pests to look for at those times,” she says.

And protocols for scouting — including the number of plants to examine, how to interpret the results and times of the season — have been readily identified by universities and are available online. “There are specific protocols for scouting that can be adapted to your farm,” she says.

For instance, during our scouting trip, Hamilton was conducting the state's annual European corn borer survey. This exact survey has been conducted by Wisconsin since 1942, using the exact same protocols. The same areas of the state are mapped, a field is targeted and Hamilton looks at 25 plants in a single row to identify corn borer injury.

“The survey gives us an estimate of fall population densities of corn borers and the amount of damage,” Hamilton says. “The survey will also give us an idea of what to expect from the first flight of moths next spring and the potential impact of first-generation corn borers in 2009.”

Ten years on the job has given Hamilton plenty of experience in moving through a field. She quickly looks at every stalk, then counts the borer-damaged plants. Time in the field: under 30 minutes.

“Farmers believe they have to look at a lot of plants in the field,” Hamilton says. “The truth is that you need to check a representative sample to determine pest populations. And that is all spelled out in the survey protocol for a particular pest.”


To be certain, it can be confusing identifying pests. Here, too, is a downfall to many a producer scouting regimen. “If you're unfamiliar with the pest you're trying to find, scouting can be confusing,” Hamilton says.

But with practice, and using available resources, identification can become second nature. “Once you've seen corn borer damage, it's relatively easy to identify the next time,” she says. “And pest bulletins also can identify the insect development stages and precisely what signs and symptoms you should be looking for in your fields.”

Add to the arsenal of scouting equipment a digital camera. “If you're unsure of how to interpret what's occurring in the field or what pest is causing the damage, take a digital photo and e-mail it to your county agent or state entomologist. They can usually identify the pest quickly,” Hamilton says. “I receive several photos each week. It's a great tool.”

Even though transgenic corn hybrids give tremendous protection against many insects, scouting those fields is also important. “It tells you if your product is working as it's supposed to, and you might even find a new insect or pathogen that could be causing a problem,” Hamilton says. “There are things you can see in the field that aren't evident from the road.”

After identifying the next stop on a map, she pulls up to the field. Before she enters, she's already taking mental notes.

“See the silks,” she says, pointing to corn silks that have been nipped off. “This indicates corn rootworm beetle feeding. The crop may be a Bt-rootworm transgenic, but that doesn't protect it against silk feeding.”

But we're tracking down the corn borer, so we continue into the field. Twenty-five plants later there's no evidence of corn borer injury. However, there are plenty of corn rootworm beetles milling around.

“While there's no way to predict with certainty next year's corn borer infestation levels based on populations this year, this survey tells us the amount of damage caused by second-generation corn borers,” Hamilton says. “The results also indicate to producers, in some cases, if planting a transgenic is well worth the cost.”

It's unlikely that producers scouting their own fields will log the 16,000-plus miles that Hamilton sees every year. And new insects, such as the soybean aphid and western bean cutworm, are adding to the number of pests that Hamilton and her colleagues across the Midwest search out each year.

“I'm continually learning in this job,” she says. “And as you continue to scout, you become practiced at identifying problems, and you have a better idea of what is happening out in your fields.”

And that can pay off by nipping problems before they create a serious economic impact.

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