Top Crop Manager

Features Agronomy Insect Pests
Treated seed packs a punch

Introductory year sent insects packing.


November 12, 2007
By Top Crop Manager

Topics

A prolonged cold, wet spring put the pressure on corn plants in 2004. It also
put new Poncho, a commercially applied systemic insecticide treatment, to the
test. Corn plants were slow to emerge and seedlings stalled in cold soils, leaving
the small vulnerable plants susceptible to a host of insect pests.

Despite the tough conditions, growers are reporting corn that was treated with
Poncho seed treatment produced uniform stands and once warm weather arrived,
showed strong vigour.

Bob Stewart farms near Chatham, Ontario, and was impressed with his corn establishment
this year. "It was the first time in about five years I didn't have to
spray for cutworm," says Stewart. He grows his corn on a ridge-till system,
alternating six rows of corn and six rows of beans. While the system can yield
great results, it also creates the perfect environment for cutworm. To protect
his crop in the past, Stewart used to spray a contact insecticide and it was
not a job he looked forward to. Application had to be done while the insects
were feeding which meant spraying from about nine o'clock at night until three
or four in the morning.

"I was skeptical about a seed treatment protecting a growing plant from
insects, but my fields had virtually no missing plants and I was hard pressed
to find a cutworm," says Stewart. "Early feeding produced small holes
in the thumb leaf and that was enough to take them out. I was ecstatic with
the results."

Protection that yields
Poncho provides both contact and systemic protection. Once the seed germinates,
the active ingredient translocates up the hypocotyl to the crown and provides
protection of the young green tissue. "The insect has to feed to die,"
explains Dr. Art Schaafsma, University of Guelph researcher at the Ridgetown
campus. "They take a few bites out of the seedling, but not enough to cause
harm."

Poncho is registered at two rates. At the low rate of 0.25mg active per kernel,
or Poncho 250, the product will control wireworm, seed corn maggot, black cutworm,
white grub, European chafer and corn flea beetle. Poncho 1250 is applied at
1.25mg active per kernel and controls all of the above insects plus corn rootworm.

Schaafsma has worked with Poncho since its early development days eight or
nine years ago.

In 2002 and 2003, Schaafsma and his research associate, Dr. David Hooker, conducted
on-farm insecticide trials at 38 sites across Ontario. "Poncho provided
yields up to 20 bushels per acre higher than untreated seed and in general,
the low rate of Poncho protected corn establishment, growth and yields,"
says Hooker.

Drop dead effective
"Overall, Poncho is one of the best materials I've seen to control wireworm,"
he says. "And 2004 proved it in spades. The extended cold period meant
corn wasn't growing much but wireworms were busy. Despite the conditions, I
saw no missing or unthrifty plants in Poncho treated corn."

European chafer pressures were heavy in 2004 and warm weather that extended
into late fall means larval mortality will be low. Schaafsma recommends that
if a grower had chafer pressure in 2004, chances are you are going to see more
of them next year. Poncho at the low rate is labelled to provide protection
against European chafer pressures up to one per square foot.

European chafers like to lay their eggs in sandy parts of fields and also near
tree lines: at least 1.5 times the height of the trees away. If scouting shows
three to five chafers per square foot, you will want to use the high rate Poncho
1250. Flea beetles were also prevalent during 2004, says Schaafsma. Flea beetles
feed on plant tissue leaving tiny holes that do not cause much damage. But they
regurgitate bacteria from their gut onto the leaves potentially transmitting
Stewart's wilt. Most field corn hybrids carry resistance to Stewart's wilt but
in sweet corn and seed corn crops, it can be a problem.

In the US, corn rootworms were horrible and seed treatments were taxed heavily,
says Schaafsma. The crop goes in the ground much earlier than in Ontario and
the delay between when insecticides are applied and when corn rootworms emerge
is lengthy. Sometimes, the material can run out prior to when it is needed.
Seed treatment doses are much lower than in-furrow insecticides and so have
an even greater challenge. But Poncho-treated crops held their own.

Strong seed trade and grower endorsement
In its first year of introduction, Poncho took the trade by storm. Even with
a late registration, the product sold out early. Seed companies are anticipating
even more demand next season and as such are encouraging growers to order Poncho-treated
seed early.

"There's increasing grower acceptance, especially once they have experience
with it. Our growers are reporting good results this year. They're saying things
such as they've always struggled getting stands in certain fields and assumed
it was damping off or something else, never considering insect pressures. In
2004, their stands of Poncho-treated corn were great," says Tim Weller,
location manager for Pioneer Hi-Bred's production facility in Chatham. "Growers
hate using insecticides in the hopper box and Poncho offers a great alternative."

Monsanto Canada treated a significant amount of last year's seed with Poncho
and is offering it next year on 52 of its 56 Dekalb hybrids and on the entire
supply of certain hybrids. "We're recommending it for most situations,"
says Jamie Rickard, seed marketing manager with Monsanto. "It's a good
product and our first season met expectations. Seed sat in the ground longer
than we like because of the weather and chafer and cutworm pressures were high,
but we heard no negatives coming from the field. That meant the product worked
and we did a good job of application."

Gary Lannin is the seed and technology sales manager for Monsanto and he heard
a number of comments from growers who were very pleased with populations achieved
in 2004 with Poncho-treated seed. "Some growers have said they've never
had such good stands and visually, it looked like every seed they planted emerged
and produced a healthy plant," says Lannin.

The most important thing for growers to remember is that seed treatments can
affect plantability. "To ensure that you have accurate seed drop, you need
to use graphite or talc to lubricate seed or planter parts," says Tim Moyes,
territory sales manager for Poncho. "Vacuum planters tend to under-plant
and finger planters tend to over-plant. Graphite lubricates the planting mechanism
at the bottom of the planter and is recommended for finger planters. Talc lubricates
the seed and is best for vacuum planters. The best advice is to follow the recommendations
of your planter manufacturer."

Mystery effect
Something else is going on with Poncho-treated corn crops in northern growing
regions, too, reports Art Schaafsma. He co-operates with several US corn rootworm
researchers and many have noted that even in the absence of insect pressures,
Poncho-treated corn crops look much better in early season than non-treated
crops. Researchers in the US midwest and further south have not noticed a similar
effect. "We're doing a co-operative study to sort out what's going on,"
says Schaafsma.