Plants can get sick, just like their plant parents
As we roll up our sleeves for the COVID-19 vaccine, we’ve learned a real-world lesson about the importance of prevention when it comes to our health.
Iowa farmers also consider prevention a top priority as they care for their crops and fields, explains Daren Mueller, Iowa State University associate professor of plant pathology and microbiology.
Farmers work throughout the seasons to prevent plant disease, just like how vaccines help prevent us from getting sick, Mueller explains.
“We all got a heavy dose of learning about (preventing) viruses. And, you know, plants get sick too, and they can get sick with the same pathogens and the same insects and the same issues too,” Mueller says.
This summer, you may see farmers or aerial applicators spraying fields to control weeds and insects when you drive out into the country.
Sometimes, farmers need to apply pesticides to grow safe, healthy food. Without pesticides, farmers would lose a significant portion of their food crops, which leads to food waste and rising costs at the grocery store.
However, pesticides are only one tool that farmers use to keep their crops healthy, Mueller says. Much of the work that Iowa farmers do to promote crop health isn’t as obvious as we drive past farm fields.
Farmers use what’s called integrated pest management (IPM) year-round to keep crops healthy while protecting the environment. (A pest is any insect, fungus, bacteria, weed or disease that hurts a plant’s health or yield.)
Mueller explains that IPM involves multiple strategies to best manage the health of crops in the most ecological and economical way possible.
IPM practices are tailored to each farm and, often, each acre of a field to target certain pests and to minimize the impact on water quality, wildlife and the environment.
“When you’re growing a crop, there’s a production side, and there’s a protection side. So (IPM) is anything on the protection side that would help make that plant stay as healthy as possible,” Mueller says.
Again, IPM isn’t just about using pesticides. In fact, pesticides are often a last line of defense. Farmers use a whole toolbox of IPM strategies to keep their crops healthy.
For example, farmers select crop varieties, or hybrids, that are resistant to certain troublesome pests in Iowa farm fields, Mueller explains. (Just like how a backyard gardener picks a tomato hybrid that’s resistant to blight.)
Farmers also adjust their planters to tighten the row spacing in the fields. Then as crops grow, the plants create a “canopy” that shadows over the space between the rows, blocking out weeds.
In addition, more Iowa farmers are planting cover crops in the fall to discourage pests and weed growth during the late winter/early spring months. Cover crops were planted on more than 2 million acres in Iowa last fall, up from only about 10,000 acres a decade ago.
Farmers also try to encourage beneficial insects that act as natural predators to pests that can harm crops, Mueller says.
Throughout the growing season, farmers walk or “scout” their fields routinely to look for any insect or disease problems before pests get beyond control.
Often, farmers and agronomist will count how many harmful insects they can find in a square foot of a field. If the number of harmful insects is too high, or above the “ economic threshold,” then action may be needed, such as spraying a pesticide.
However, if the number of insects in a field is below the economic threshold, then the farmer may decide it’s not worth the cost or effort to use a pesticide, Mueller says.
Each year, farmers face different pest pressures on their crops, just like how some years, we have more mosquitoes in Iowa after a wet spring, Mueller says.
The choice whether or not to use a pesticide ultimately depends on the individual farmer, who uses real-time data and science to make decisions to protect their crop’s health.
“In farming, there are a thousand decisions that happen every day. So sometimes, when you see people out spraying (pesticides) in the spring, they’re balancing those 999 other decisions,” Mueller says. “(For example), they may be dealing with the risk of whether you should spray now or in the next four days because it’s going to be windy.”
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