Insecticides and Crop Scouting - Parrish and Heimbecker, Limited

Scout to spot insect outbreaks early

Be prepared, but check thresholds before you spray

Crop scouting is the best way to get to know field conditions, identify insects present, determine threshold levels, and know when to act to protect yield. It’s the economically and  environmentally sound prerequisite to making pest management decisions, reducing uncertainty, and ensuring you spray only when necessary. By utilizing Integrated Pest Management (IPM) strategies, you can control and prevent problems before the occur.


Familiarize yourself with problematic and beneficial species 

It’s important to develop tolerance for insect presence in your crops. Get to know both the problematic and beneficial species. Not every insect is there to cause harm. Many help, acting as natural predators to protect your crop or pollinating your plants. Terrestrial and avian animals also provide pest control—birds eat worms and grasshoppers, for example.

Crop scouting can help you build both knowledge and tolerance, and be prepared when action is truly necessary. Talk to an agronomist trained in thresholds and beneficial species, and ensure they are not focused on boosting product sales. When you must spray, time your application to protect beneficial insects. Otherwise, spraying may destroy those too, making the situation worse when pests move back in and there are no natural predators left to control them.

Carry a scouting kit  

Carry a scouting kit that contains the tools you’ll need to collect, record and preserve samples: clipboard, paper, pen, tweezers, paper or clear plastic bags, 10X magnifier, sweep net, pocket knife, flagging tape, and a pest identification guide. (Field heroes has an excellent FREE guide that can be ordered here).

Scouting tips 

  • Begin scouting weekly at emergence, more often in higher value crops and those more susceptible to attack. 
  • Assess overall field appearance, then check edges, centre, low and high areas.
  • Choose an appropriate scouting pattern, considering the field shape and ease of access, such as a W, X, Y or Z pattern (for uniformly distributed insects). 
  • Check specific areas for insects that populate those (high, low, wet or dry sections). 
  • Count mobile insects based on number present per square metre. 
  • For less mobile insects, shake the plant and count them on the ground.  
  • Swing a sweep net at arm’s length through the canopy to sample mobile or small insects (such as lygus bugs). 
  • Check plants from roots to shoots, on upper and lower sides of leaves, flowers and pods, for damage or abnormalities. 
  • Check at least five locations in fields under 100 acres, at least 10 in larger fields. 
  • If you find something suspect, contact your P&H Representative to help with assessment. 

Insects to be aware of this year:

Western Bean Cutworm – found in corn and edible beans. Focus scouting efforts on later planted corn. Begin scouting when the first moths are noticed and continue until after the moth population peaks. Moths will target pre-tassle corn to lay their eggs.

Armyworm – found in cereals, corn, and hay. When your cereal crop matures, they will move to the next tender grass species. Early infestations are often found at the field edges.  Armyworms feed almost exclusively at night.  If possible, scout in the early morning or early evening.

Soybean Aphids – as the name suggests, found in soybeans. First, walk to a random spot in the field. Pull a plant, turn it upside down, and give it a quick scan to see where the aphids are located. The current threshold for late vegetative through R5 stage soybean is 250 aphids/plant with 80% of the plants infested and populations increasing

Treat problem pests when thresholds are present 

Your P&H Representative can provide help you identify the insect and provide treatment recommendations. P&H provides a variety of pest management options from suppliers such as BASF, Corteva, FMC, Bayer, Syngenta and Nufarm. Contact your local P&H to discus crop protection products that fit your farm.