Problem weeds take root
Localized weeds are tough, competitive and could gain a toehold in a field near youBY TOM BUTTON
Corn and soybean growers who think the Y2K bug is the worst they have to fear from the new millennium should start walking their fields.The next generation of weed control headaches is taking root today. These weeds are tough, they're competitive, and if they aren't eliminated before they gain a toehold, they can be darn near unstoppable.
"I'm working with a couple growers who have biennial wormwood," reports Peter Sikkema, weed researcher at Ridgetown College. "It's a real problem....If they don't control the wormwood, they might as well not plant, but there's very little I can tell them to help.
"Unfortunately," Sikkema adds, "that's the kind of weed control problem we're seeing more and more."
Because new, problem weeds are also low-acreage weeds, it isn't practical for researchers to set up intensive tests to see which herbicides give the best control, or for companies to register new chemicals.
Herbicide experts such as OMAFRA's Hugh Martin identify three key scenarios that make fields vulnerable to today's localized weeds: frequent repetition of the same herbicide program, reduced tillage and reduced rotations. The best preventive, Martin says, is to keep the weed control program flexible. "Don't always hit the weeds the same way." Use different chemicals and timings.
When unrecognizable weeds are found, a call to the pesticide dealership will usually bring out company technical staff who can identify the weed. Government crops advisers can also help. If still stumped, weeds can be dug up and sent to the Pest Diagnostic Clinic at the University of Guelph. Call (519) 767-6256 for details and costs.
Often, says Cargill agronomist Jim Shaw, the experts will know a lot about the field's history simply by identifying the weed. "Tufted lovegrass is the result of using a lot of Pursuit," Shaw says. "In most cases, so is three-seeded mercury."
No-till brings on perennials such as dandelions and sowthistle and biennials such as wild carrot as well, but is also linked to annuals such as spreading atriplex.
The spread of no-till annuals can be an unpleasant surprise. Many no-tillers have switched to post-emerge sprays to get in-crop suppression or control of perennials such as quackgrass and milkweed. For spreading atriplex, however, the best control options are pre-plant and pre-emerge with sprays including metribuzin, Broadstrike-Dual and linuron.
University of Guelph weed specialist Clarence Swanton says growers shouldn't abandon no-till because of weed control. Overall, he says, no-till reduces weed pressures by forcing seeds to overwinter on the soil surface, where many are killed by weather extremes, eaten by birds and rodents, or attacked by moulds.
Swanton has counted seeds in Elgin county plots that had been no-tilled for eight years and compared the results to plots that had been plowed for the same years. Plowed plots had 5,000 seeds per square foot. No-till plots had 400.
The seed bank in no-till plots, however, had more than twice as many species, averaging 38 compared to the 15 in the plowed plots. No-till plots had escapes from 27 species, compared to seven for plowed soil.
Weed experts are getting more identification calls. When Sikkema hits the meeting circuit, he's finding a big change. "I used to talk about general weed control," he says. "Now, as soon as I start talking, the questions start coming about how to handle problem weeds."
Guelph and Ridgetown have set up a new weed control program for problem weeds because these weeds are too low-acreage to attract interest from the companies. Targetted weeds include groundcherry, horsenettle, broad-leaved plantain, heath aster and more than a dozen other tough weeds.
© copyright 1999 Agricultural Publishing Company Limited.
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Fusarium fungicide falls flat at PMRA
Michigan and Minnesota wheat growers will be spraying Folicur to protect their crops from fusarium head blight this June. Ontario growers can only pray for dry weather.Folicur is the best-tested fungicide for controlling fusarium, says Art Schaafsma, disease specialist at Ridgetown College.
Folicur is illegal in Canada, however. It's been on the market in Europe for 20 years, and several U.S. states have convinced the Environmental Protection Agency to make it available under a emergency registration.
North of the border, the Ontario wheat board had been working with Manitoba growers to get similar fast approval, but the bid fell flat. Canada's Pest Management Regulatory Agency would only issue a trial permit for research use in 1999.
"Now we have to hope for a temporary registration for the year 2000," Schaafsma says. "Folicur is the only realistic shot we have, at least until the breeders come up with resistant varieties."
Fusarium is Ontario's worst wheat disease. It's sporadic, however, with little damage in dry years but epidemics in years such as 1997 that have wet Junes.
The fungus strikes at flowering, when the heads are fully exposed and the anthers are starting to emerge. The spores - which Schaafsma says are "everywhere" - are benign if they land on anthers that are dry. If the anthers are continuously wet for 12 to 24 hours, however, the spores will germinate and invade the wheat plant.
If the crop has been treated with Folicur just before it gets to that sensitive stage, it will be able to shrug off most of the fusarium attack, no matter how much rain falls or how long the crop is wrapped in mist.
Schaafsma's tests show that Folicur will stop 50 to 90 per cent of the infection. It will also top most of the production of toxic contaminants, including vomitoxin. Control rates depend on timing and coverage, and also vary by variety. In general, varieties with better genetic tolerance to fusarium also show a higher control rate when sprayed with Folicur.
Crops would have to be sprayed at 50 per cent flowering. Spray rigs would also have to be set up with paired nozzles facing forward and rearward in order to cover the entire head.
Water volumes would be critical, too, Schaafsma says. Rates above 25 gallons per acre could actually help fuel the disease by giving the spores the water they need to germinate.
To date, the only registered use for tebuconazole - the active ingredient in Folicur - is in the seed treatment Raxil. Bayer says that if wheat groups get Folicur registered, it will import the fungicide for Ontario and Manitoba. Cost in the U.S. is $13 per acre.
"It won't be as simple as just going to the field and spraying," Schaafsma says. "We'll need to monitor the weather and be very precise with our applications, but it will be worth it if we can put the brakes on fusarium." - Tom Button
© copyright 1999 Agricultural Publishing Company Limited.
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Moisture key to double cropping
An early wheat harvest could prompt many growers to roll out the soybean planter in JulyBY TOM BUTTON
With wheat crops racing toward a harvest that appears to be at least a week ahead of normal, 1999 could provide another opportunity for double-cropping soybeans. The question is:Will there be rain?
Double-cropped soybeans in 1998 yielded anywhere from seven to 40 bushels an acre. On average, it takes 15 bushels to pay for seed and field operations, including planting and harvest.
"It comes down to whether you're willing to take the risk," says Chris Brown, provincial government crops adviser at Woodstock. "If you don't get moisture, you aren't going to get a crop," says Brown. And an early frost can be devastating.
In Essex county last year, Claire Sherk harvested 40 bushels an acre from 100 acres of double-cropped soys planted on clay. Another 30 acres on black sand yielded 33 bushels despite heat stress.
Sherk had his wheat in the bin by July 7, but immediately got a six-inch cloudburst that delayed soybean planting for a week. He used a litre of Roundup for weed control, then went straight into the wheat stubble with a no-till drill, planting the 3200 heat unit variety CX260C at 75 pounds per acre. Soys were harvested October 30 and 31 at 12.6 per cent moisture.
Sherk figures his costs at $30 an acre for seed, $20 for planting, $15 for weed control and $32 for harvesting, for a total $97 per acre. While he knows there's risk from dry weather and early frost, Sherk says that needs to be balanced with the potential of "a significant profit." With soys at $9 per bushel, he reaped a net $263 per acre on the clay and $200 from the sand.
Brown recommends growers keep their eyes on the weather forecasts, and also on their costs. Wheat harvest must be early, but there must also be enough moisture in the soil or in the forecast to get the crop off to a fast start. The combination, Brown says, "is about one year in 10."
Unlike corn, which is driven almost totally by heat unit accumulation, soybeans respond to changes in day length. That's why growers need only lop 200 to 300 heat units off their varieties.
Even so, getting the crop to harvestable moisture is a race against the calendar.
It takes 51 days to go from full bloom to full maturity, including nine days to get from full bloom to early seed development, followed by 15 days to full seed development, another 18 days to get to the beginning of physiological maturity with 50 per cent leaf yellowing, and a final nine days to complete maturity.
Brown warns that frost during early seed development can cut yield potential by 50 to 60 per cent. Frost at full seed development can cut yields 20 per cent. Once the crop gets to beginning maturity, yield losses may be less than five per cent, but there could still be extra drying costs and discounts due to green beans.
The goal is a healthy yield. Even if the crop must be plowed under, however, Brown says it will have long-term benefits for the soil. As a green manure, the crop will boost organic matter. Through the summer, the growing crop will also keep soil micro-organisms healthier than if the field was left bare.
Key advice is to keep cost to a minimum. It may make more sense to use bin-run seed, providing the parent stock was from a variety with the right maturity rating. It can also be a good idea to bale the straw and to scout for weeds that may have been lurking under the wheat canopy and that will be ready to take off when they're exposed to sunlight.
"A lot also depends on the other jobs that need your attention," Brown adds. "If you have a forage crop ready for cutting, that's where your priority should be."
© copyright 1999 Agricultural Publishing Company Limited.
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Crop adviser's certification threatened
Maverick consultant Merv Erb is still getting under the skin of the pesticide industry. Now, the Fertilizer Institute of Ontario is trying to strip Erb of the right to call himelf a certified crop adviser (CCA)."It is common knowledge amongst several Ontario retailers that Erb recommends special mixtures and application rates that aren't on the label," TFIO executive vice-president Tom Sawyer wrote in a letter to the CCA's standards and ethics committee.
"Erb has clearly shown no respect for the laws of Ontario and Canada," Sawyer wrote, adding that Erb has been convicted of smuggling U.S. pesticides into the province.
The action would be a moral victory: It couldn't put Erb out of business. And it may backfire. Erb is getting vocal support from farmers and the chairman of at least one commodity group.
The CCA program is a voluntary certification system for crop consultants. It's run by the American Society of Agronomy in co-operation with state and provincial committees.
To qualify, consultants must pass a difficult two-part exam. Failure rates have exceeded 50 per cent. Candidates must meet criteria for education and field experience, and they also must live up to the society's ethics bylaws.
A committee insider said charges against Erb boil down to his actions eroding the public's faith in agronomists, primarily because of his conviction for smuggling. Most of Erb's off-label recommendations appear to be for below-label rates. While they're technically illegal, Canadian officials have made it clear they won't prosecute farmers for applying less pesticide than they're allowed to.
Erb's case is being tried in Michigan, where he earned certification in 1994. The reason for crossing the border, he says, is that Ontario didn't start up its CCA program until 1996.
A stream of letters has also crossed the border to support Erb. Alex Hart, chairman of the Ontario Colured Bean Growers Association, wrote that Erb "may have put his foot over the line from time to time." But, he added, "without his knowledge and great desire to see the Ontario farmer be sucessful, our coloured bean industry would not be as advanced as it is today."
"Erb's knowledge of crop and pesticide recommendations is second to none," wrote farmer and custom applicator Don Good. "His integrity is above reproach."
Dresden's Gord Brooksbank, honoured several times for environmental stewardship, wrote "he may have broken the law, but only to get safer and better products into Canada...to punish him further is very unjust."
Varna's Bev Hill wrote that while he hasn't been a client of Erb's, he has "solicited his advice on numerous occasions. His advice has always provided me with excellent results with significant financial savings. If [his off-label recommendations equate] to reduced pesticide use and reduced costs and acceptable results, then I would suggest" his counterparts follow suit.
It's expected the Michigan ethics committee will rule on the case within a few weeks. It can strip Erb of his CCA designation, suspend him or issue a reprimand.
Erb says he is taking the challenge in stride. Whatever the outcome, he says his practice of recommending below-label rates will continue to be a flashpoint for the rank-and-file pesticide industry. "The battle rages on," he says. Sawyer, meanwhile, is retiring at the end of July. - Tom Button
© copyright 1999 Agricultural Publishing Company Limited.
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Foliar fertilizers failing tests
Faith in foliar fertilizers has fizzled after two lacklustre years of on-farm corn and soybeans tests. A third year of trials is under way, but consensus is the strategy is headed nowhere."We'd need a 20-bushel yield response in soybeans this year in order to make it economically viable on average," says Peter Johnson, OMAFRA crops specialist who oversaw Middlesex foliar trials over the last two years. "You should never say 'never,' but it's a real long shot."
The University of Guelph is gearing up for complex tests using radioactive nutrients to track how much nitrogen can be absorbed by corn leaves. Researchers will also continue with their third year of yield studies at Woodstock.
A team led by ministry corn specialist Greg Stewart will also look at changing the way the fertilizer is applied. Instead of spraying only at the six- and 12-leaf stage, they'll also spray after silking to see whether they can pump more nitrogen into the ear.
"I don't want to pre-judge it, we still have another year to go, but we haven't seen any response with our work to date," Stewart says.
Foliar recipes vary, but typically include high-grade urea along with U.S. additives including Sol-u-bor and Tec-ma-gam. Costs for a single application are about $21 per acre, although it's often recommended that the mix be applied two or even three times.
In 77 on-farm plots last year organized by the Innovative Farmers Association of Ontario, soybeans that had been sprayed with foliar fertilizer yielded 43.8 bushels. Soybeans that hadn't been sprayed yielded 44.2 bushels.
Results in corn were similar. Plots that received two foliar applications at a cost of $46 per acre yielded 132.3 bushels. Plots that weren't sprayed yielded two bushels more.
In tests by the Middlesex Soil and Crop Improvement Association over the last two years, single foliar applications gave a 1.4 bushel yield decrease in soybeans. A double application gave an average 0.1 bushel benefit.
At best, Johnson says, the benefits of foliar fertilizing are hit and miss. But since it would take a seven bushel yield increase to pay the cost of a double-spray foliar program, and since there haven't been any yield increases in the first two years, Johnson calculates there would have to be a 20 bushel increase in the third year.
Stewart says there's little scientific back-up for foliar fertilizing wherever it's been tested.
"Foliar fertilizing is an appropriate strategy for some of the minor nutrients," Stewart says. "When you're talking about macro-nutrients, the quantities that the plant needs are much larger than they appear to be able to take up through their leaves.
"That," he adds, "is why plants have roots." - Tom Button
© copyright 1999 Agricultural Publishing Company Limited.
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