Updated by: Dr. Art Shaafsma from The University of Guelph, Ridgetown Campus,
Wireworms were active last week so it would be a good idea to get the baits out ASAP if you want to exceed the 50% neonic rules. Baits work better for wireworm than digging, but while you install baits and find the right number of wireworms you are done. Baits result in fewer false negatives, saying they are not there when in fact they are. The most reliable bait we have found is a 1:1:1 mix of corn, wheat and edible bean seed (you can substitute soybean for edible, and the most important ingredient is the wheat). The seed can be bin run, commercial grain untreated, with decent germination (>75%). Pre-mix seed and soak overnight. For best results put about 1 cup of soaked bait into the bottom of a nylon mesh bag (onion bag) and roll it up into a “sausage”. I prepare and fill the bait bags the day before and soak everything overnight. Lay the bait-bag “sausage” on the bottom of a trench about 3 inches deep, and mound loose moist soil on top (about 2 inches of soil on top of bait bag.
This spring I had the most success placing traps in the sandiest parts of fields immediately adjacent to perennial grasses (along grassy waterways, ditch and fence lines, laneways, yards, and tree lines). I also trapped them more often in soils with the highest organic matter, but these low areas would need to be well drained. A good compromise would be to install the trap just inside the area where the soil color shifts from light to black. In some smaller low spots you could squeeze in two traps 10 m apart to comply with the regulations. Avoid the driest soils and the soils that tend to flood.
Leave the baits out for at least 7 days and preferrably 8-10. You want the seeds sprouting and developing roots, but not too much root mass or it will make the assessment more difficult.
You could place the soaked bait directly in the trench without a bag, but then be prepared to more than double the time required to dig it up and sort through the materal.
I have observed that once a wireworm finds the bait it tends to stay around because food is plentiful.
Time saving sequential sampling. The regulations state that the baits have to be placed in the field. The only restriction is that there must be at least 5 traps, the traps must be at least 10 m from the nearest neighboring trap and you must report their location. Upon assessment you must report five results . If you find 5 wireworms in the first trap that you assessed then you can report 0 in the remaining traps without assessing them and reach the threshold required. Likewise if you report 2 in the first trap and then 3 in the second, you can report 0 for the remaining traps.
Problems with Vermin: Raccoons, squirrels, skunks, rodents, turkeys, deer, dogs all seem to be attracted to these baits. Avoid areas of the field where these vermin are common. If the risk is high increase the number of traps you put out proportionally up to double the number. When it comes time to assess, you may only assess 5 traps so pick the most likely to contain wireworms from the traps that have not been damaged by vermin.
Grubs should also be big enough to find by now if they are there, these are best found by digging up plants, and sod around field edges near treelines on knolls.