Fewer borers damage corn
But there are hot spots where growers will have to harvest early to avoid dropped ears and broken stalksBy TOM BUTTON
How lucky are you? In most Ontario corn fields this fall, damage from corn borers is slight. Overall, borer-related losses are predicted to be as low as realistically possible.But there are hot spots-individual fields where micro-climatic conditions have sparked severe corn borer injury will likely be as bad as recent years.
Knowing whether your field has borer damage could affect yield and harvest ease. If damaged fields are left as late as clean crops, there's a serious risk of dropped ears and broken stalks, warns Cathy Soanes, agronomist with Novartis Seeds.
Soanes supervises a team of 60 seed dealers who are walking 320 fields this year as part of the biggest borer scouting project in the province's history. Initial results show that, on average, 10.4 per cent of plants are infested.
Most areas, however, also have scattered fields where more than 20 per cent of plants are damaged, Soanes reports.
Also critical is the type of damage. If 10 per cent of plants have limited leaf feeding, the impact on yield may be minimal. If 10 per cent of plants have ear damage, on the other hand, it could lead to a 10-per cent yield loss.
If damaged ears turn mouldy, the economic consequences could be even greater, especially for pork producers.
Albert Tenuta, pest specialist for the provincial agriculture ministry at Ridgetown, says an overall 10-per cent average is good news for many growers who stayed with conventional hybrids instead of paying the extra $8 per acre for Bt genetics. Yield losses overall should be lower compared to recent years.
In fields with heavier pressures, however, losses could easily reach five to eight per cent or more, he notes.
"It isn't safe to assume that just because other fields in your area are relatively clean that your field is clean, too," warns Tenuta.
Part of the reason why one field gets hit worse than others has to do with weather, he explains. The adult borer moths need clear, calm nights for their mating flights and to fly into fields for egg laying. If local conditions favoured the pests, borer infestation could be severe.
Some fields have a built-in higher risk, however, he says. For instance, fields that are planted earlier than their neighbours may attract more moths. As well, as the season progresses, moths may seek late-planted fields, since plants will still be tender.
Borer moths hide in weeds during the day, so fields that have a grassy border or abut weedy woodlots or fencerows may see more egg laying. So may fields that have more in-crop weeds.
Tenuta and Soanes recommend keeping an eye on fields. From the laneway, look for broken tassels that may indicate weak stalks caused by borer tunneling. Also be on the alert for red leaves, caused when sugars get trapped in the leaves because borers have cut off channels that would otherwise take those sugars to the ears.
If you see broken tassels or red leaves, get out of the truck and into the field, Soanes says. "You may have to get ready to harvest that field the first day you can."
Tenuta also recommends scouting fields by quickly inspecting 10 plants in each of at least five locations across the field, and then calculating the percentage of infestation. Look for pinholes in leaves and also for the build-up of brown excrement (called frass) in leaf axils.
If borer damage is severe, it may be worthwhile to harvest the field early and pay the higher drying fees rather than wait and risk losing yield to ear drop and lodging.
Tenuta warns, however, that growers who find clean fields this
year
shouldn't jump to the conclusion that Bt hybrids won't pay next
year. "We
appear to be near the bottom of the borer cycle," he says. "But
that
doesn't mean anything in terms of how much damage we might see
next year.
"It's all going to depend on the weather during the moth
flights."
back
Need help choosing hybrids?
The new Ontario corn brochure will be packed with data to help
growers
pick the best hybrids for their farms
By TOM BUTTON
Get ready to spend some extra time studying corn hybrids this winter. The old brochure from the Ontario Corn Committee is blossoming into a 16-page booklet with reams of data.For the first time, the report will carry yield results from each of the 20 test locations, as well as averages for all tests within each maturity zone. In the past, the committee published only the averages.
The new report will also feature extra codes so growers can spot hybrids with special traits, such as herbicide resistance or high-oil genetics.
With over 400 hybrids under test this summer, the Ontario performance trials keep getting bigger. This year's 10-per cent hike officially kills speculation that the tests would collapse following de-regulation of corn licensing two years ago, the committee says.
The upshot is that corn growers will have access to unbiased, third-party comparisons of corn hybrids, says Neil Moore, OMAFRA crops specialist at Port Perry and chairman of the provincial corn committee that supervises the trials.
Ken Hough, agronomist for the Ontario Corn Producers Association, says the increased number of hybrids shows that companies recognize the importance growers attach to performance trials.
In a survey earlier this year, the corn association found 83 per cent of growers consider the test report important. Only 17 per cent said they don't use the report.
This winter's report will be the largest ever because of the number of hybrids and an increase in the number of corn companies -19 companies, up from 17 last year.
Most companies say that although the trial system is voluntary, they intend to stick with it as a key part of marketing strategy. Zeneca Seeds, for example, puts new hybrids into the trials after one to two years of in-house testing. By the time the new hybrids have three years of testing and are included in the brochure, the company is ready to start limited sales.
"The growers need it; the industry needs it," says Len Hawkins, Zeneca sales manager. "You'll see all of the companies continue to support the system. It's exactly the kind of independent validation of our hybrids that we need."
The companies pay the $85,000 cost of operating the trials, Moore says. Fees range from $45 to $60 per test location.
Hough thinks growers will like the location-by-location reporting. For instance, instead of having an average of the tests at Ridgetown and St. Thomas, a grower at Thamesville will be able to check out the yields at each site. Not only would Ridgetown be closer, but the grower would also have a better feel for growing conditions and how they may have influenced hybrid growth, Hough says.
The bad news this year is related more to weather than industry
politics.
Because of drought and frost, three locations had already been
abandoned by
the end of August. It's expected several more may be dropped
after harvest
because of too much stress-induced yield differences among the
plots. "We
can't control Mother Nature," Moore says.
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SEEDBED
By Keith Reid
Getting wheat off well
Too often, wheat is the forgotten crop in our rotations. We throw
the seed
on the ground after the beans come off, spread a little nitrogen
next
spring, combine it in the summer, and then complain about the
poor yields
for the rest of the year.
With a little more attention to management, wheat should be a crop you're proud of, rather than one you merely tolerate. A big part of this management is ensuring proper fertility.
Building a strong foundation
The key to fall growth is establishing a strong root system and
crown that
will support a flush of top growth next spring - in other words,
looking
after the parts of the crop we don't usually look at. A large
vigorous crop
of green may be showy, but it isn't necessary; indeed, in areas
with snow
mould it isn't desirable.
Wheat will consistently respond to additions of phosphorus, the nutrient most commonly associated with root growth.
The most efficient way to add phosphorus is with the seed, either as a liquid or granular fertilizer. Rates should provide 15 to 30 pounds of phosphate per acre, or more if the soil test calls for it. What type of fertilizer you choose to use doesn't matter; the key is application. This banded phosphorus is immediately available to the young seedling, and is protected to some extent from immobilization by the soil. It would take a much higher rate of broadcast fertilizer to give a similar benefit to the plant.
Potassium as antifreeze?
Traditionally, we added potassium to fertilizers for winter wheat
to help
with winter survival. After all, it works for forages, right?
Trials in
Ontario have shown that, while adequate potassium is important,
it is not
as critical as phosphorus.
Potash may have a role, however, in disease resistance in winter wheat. There is little research in Ontario, but trials in Western Canada and in the northeastern U.S. have shown reductions in disease when potash is applied. We don't know for sure if this is the effect of the potassium, the chloride, or both working together. More research is required to sort out what is happening, and what rates and application timing are needed for best effect.
What about nitrogen?
We know that wheat is very responsive to nitrogen, but the
question of how
much is needed at planting, and how much should be applied in
the spring,
always comes up. Trials at Guelph and Ridge-town have shown no
advantage to
applying nitrogen at seeding, compared to applying all of the
nitrogen in
the spring. The exception is that a little bit of nitrogen (one
part N to
four parts P) will increase the uptake of phosphorus when the two
nutrients
are applied together.
But some farmers are applying significant amounts of nitrogen - up to the entire crop requirement - in the fall. This is based on Prairie practices, where a large part of the nitrogen for spring crops is applied in the fall as anhydrous ammonia.
This gets one job out of the way, I suppose, and it utilizes an inexpensive source of nitrogen. It will work effectively in some years, but there's a serious danger that the nitrogen will be lost through denitrification or leaching before the crop can make use of it.
On the Prairies, fall application of anhydrous ammonia does not start until the soils have cooled to below 5 C, so the ammonia won't be immediately converted to nitrate. Obviously, we would like our wheat in the ground before the soil is this cold. Fall application of nitrogen also increases the risk of ground water contamination, as well as a loss of production through nitrogen deficiency.
Plain and simple, large rates of nitrogen in the fall are a bad
idea, both
for your environment and your bank account.
Keith Reid is OMAFRA soil fertility specialist, Walkerton
(kreid@wcl.on.ca)
back to September 7, 1998 Issue