There's more to scouting your fields than you think

Sunday, April 3, 2011

Few farmers make good field scouts. Hiring someone to do it for you may be a better choice

by PAT LYNCH

How many times have you read a conclusion to an article which advises you to "scout your fields to find out?" It is certainly the way to watch for insect buildup, weed escapes and diseases initiation. You also can scout for timing of fungicides or herbicides.

But there is more to scouting than the above. Few farmers make good field crop scouts. Most do not have the time when scouting is critical. Some cannot distinguish between pigweed and nightshade or ragweed and red clover at the cotyledon to first leaf stage. This is the stage when you have to know what you have.

Most growers cannot distinguish between the start of Septoria and powdery mildew on wheat. Nor do most know where you check for the start of these diseases.

Scouting for weeds is simple if you know how. Too many times, someone walks into a field and sees some weeds and decides to re-spray everything. Or they check part of the field and finding no weeds presume it is weed free.

A good scout will check all relevant parts of a field. They will be able to calculate the density of each weed species. A low level of many grasses that have escaped in corn or beans probably will not affect yield. Broadleaf weeds have a bigger impact on yield. Their seeds survive in the soil longer than grass seeds do.

The advent of glyphosate-resistant weeds has made good scouting more important than ever. Hired scouts may not notice the first ones, but I believe they will find them quicker than fields that are not scouted.

There are two other reasons why you should hire someone to scout your fields rather than do it yourself. Many producers' eyes are not trained to see certain things. A scout who is checking fields every day can spot the smaller weeds more easily than someone who is not doing it as regularly. The other is record-keeping. Few producers who do check their own fields keep adequate records. You will remember if a farm has group two resistant nightshade or glyphosate-resistant giant ragweed, but you will not remember other weeds there.

A good scouting program includes taking populations and stages. You need this information to get some idea of the difference between seed drop and stand. You also need to know the difference in emergence. A crop that emerges over an eight-day period can lose six to eight per cent of its yield. It is easy to calculate emergence time based on staging at the three-to-six leaf stage of corn. Later, it is harder.

Insect scouting is challenging. You have to know army worm will probably show up in lodged wheat first. You can find army worms every year if you know where to look. Then you have to check for parasites. I know of fields where army worms were found and unneeded spraying occurred because the impact of parasites and the stage of the armyworm were not understood. And I cannot imagine too many growers using a sweep net properly.

Scouting for soybean aphids is one of the times when growers can do their own scouting. But, even then, you have to be able to count and monitor them from day to day.

There are many tasks you can let others do so you can manage your crops. Field scouting is one of these. BF

Consulting agronomist Pat Lynch, CCA (ON), formerly worked with the Ontario agriculture ministry and with Cargill.