KINBURN - The bad new is that Bruce Hudson has European corn borer (ECB) in his fields.
The good news is that destructive insect is limited to the "refugia" planted around the Bt hybrids that comprise 80 per cent of his corn acreage.
Hudson, of Panmure Farm, near this West Carleton community, has been planting Bt corn for the past six years and has increased the acreage of his NK Bt hybrids each year to the recommended maximum of 80 per cent of his acreage.
His farm had been plagued for years by heavy ECB infestations and he told The AgriNews during a tour of his property Aug. 29 that he could never get a satisfactory answer as to why his acreage seemed to be a favourite lunching spot for the larvae that use a corn plant as their host, tunnelling into stalks and attacking the ears of open husk varieties.
Research has failed to come with a definitive answer on the how, what, when, where and why of ECB infestations.
Private agronomist Paul Sullivan of Kinburn, who helps Hudson with his crop decisions, said during the tour that infestations seem to be totally random although certain weather conditions - particularly still June nights - tend to increase infestations.
Hudson, a big, beefy man, is dwarfed by the stalks towering over him in one of the fields used for NK’s ECB scouting program and says his results "easily match NK research" figures which show that Bt corn yields an average of an extra 8.9 bushels per acre over matching non-Bt hybrids.
Bt is scientific shorthand for bacillus thuringiensis, a naturally occurring soil bacterium from which a protein is extracted and through biotech introduced into hybrids which, when planted, produce their own proteins to repel the corn borer.
This protects the crop from the borer, which spends the majority of its life burrowing inside the corn stalk where traditional spraying programs can’t reach it.
It’s the same protein and bacterium that organic farmers, who have proven its safety, have been using for decades. Cathy Soanes, NK’s technical information manager, told The AgriNews from her Arva, Ont., office that Bt has been used for over 40 years and had proven to be a "perfectly safe" control mechanism.
The majority of Hudson’s corn is used for feed on his 120-head feedlot and 150-sow farrow-to-finish operation with about 100 to 200 tonnes sold
locally, much of that Ritchie’s. He says he sees an immediate advantage to the Bt varieties, especially in feeding hogs. The Hudsons also grow sweet corn and the lack of Bt varieties for this consumer crop provides a dramatic infestation comparison, he says.
When asked about the randomness of ECB infestation, Sullivan and NK agronomist Jim Simonds of Kemptville said it is an unpredictable pest, with tests showing different levels "from field to field and area to area".
One development that is starting to be seen as a trend is that first-year corn is not immune to infestation, as many think. Early planted fields also probably need Bt varieties as much as any other land, they said. This trend was in evidence in 2000 when wet weather delayed planting and the incidence of corn borer dropped accordingly.
Tunnelling through the stalk is the major damage created by the ECB larvae as they eat their way through the host plant. This creates a weak stalk and can lessen nutrient flow to the plant’s peripheries. There is also secondary damage created when the larvae hatch from the underside of the plant’s leaves, where the adult moth lays them, and bore into the stalk. These entry points - the surest way of detecting the presence of ECB - can create an easy entrance for stalk rot and larvae feasting on the cob, particularly those with open husks, can increase the incidence of ear mould.
Growers should check their fields twice for infestations, at pollination and just before harvesting. Soanes says scouting in September is especially important because damage is more manifest at this time of the year and growers have to consider this when deciding when to take their crop off.
Scouting will tell whether a heavily damaged crop should be taken off quickly rather than left standing to achieve the false economy of cutting dry-down costs.
Damaged stalks and ear drop will significantly reduce yields, leading to a situation not unlike that old television ad of "you can pay me now, or you can pay me later".
Tell-tale signs of infestation are the entry points, ear mould, stalk rot, drooping plant tips, damaged tassels and brittle nodes.
But the only sure way to detect their presence it to cut a stalk, slice it and check for tunnelling left behind by the one- to one-and-a-quarter-inch larvae.
The signs were evident in six of the 10 stalks - N17-K5 non-Bt, a Liberty-resistant variety - cut from Hudson’s 12-row refugia headland and in all six of the stalks from non-Bt hybrids cut earlier the same day near Napanee.
Simonds says it’s a safe bet, from ECB scouting reports of over 1,000 fields over the past five years, that all non-Bt fields in Eastern Ontario have some degree of infestation.
Results from scouting fields are sent to Soanes. The length of tunnelling, size of the larvae, soil types, tillage practices and crop rotation practices are fed into the company’s database, which is now large enough, Simonds says, to be able to provide meaningful findings.
Hudson’s is one of 560 farms involved in the scouting project The program started in 1995 as a master’s program for Tracey Baute, a field crops entomologist with OMAFRA. She scouted 80 locations over two years. NK expanded the program in 1999 through its dealers, and 300 locations were scouted. Last year this grew to 400 and this year its stands at 560 across the province’s most intensively planted corn acreage.
From the Archives:
AgriBusiness, September 2001
