Corn rootworm is still the toughest corn pest in Ontario, even though the vast majority of the province's corn growers have stopped applying insecticides to kill it.

For farmers who need to plant corn on corn, the choices are as hard as ever. The new solutions insect researchers had hoped would end the game of rootworm roulette aren't going to be much help after all.

Rootworm control is as big a gamble as ever. There are even fears that rootworms may make short work of the enormous scientific effort going into the new transgenic, biotech hybrids.

Only seven per cent of the province's corn crop gets treated with rootworm insecticides, estimates Tom Hartman, crop insect expert for the provincial agriculture ministry. That's down from nearly one-third of the crop 10 years ago.

Yet of every 10 acres that get treated, only one acre gets an economic benefit. The other farmers are throwing their money away and they may be destroying beneficial insects that would keep other pest insects in check.

There's no easy, practical way, however, to tell which fields really need insecticide.

The simplest control strategy is rotation, as most farmers have learned. Rootworm only attacks crops that are planted in fields that had corn the year before, allowing eggs to hatch in the spring.

So many farmers are rotating, the total rootworm population is dropping, says Cliff Ellis, insect researcher at the University of Guelph.

"The insect needs continuous corn to maintain its numbers," Ellis says. "There just isn't that much continuous corn left." Oddly, the population is falling, even though farmers are using less insecticide. Ellis isn't surprised. "The insecticide only killed the insects in a narrow band near the seed," he explains. The rest of the field still produced huge numbers. Rotations, however, stop the pest.

In the late 1980s, researchers learned that insecticides paid for themselves on about one-quarter of fields. Today, they only cost out on one-tenth of fields because there are fewer insects.

Ellis has struggled to find a way to determine which acres need insecticide. Farmers can scout their fields in August to count how many beetles are on their plants. If they find an average one per plant, they should put insecticide in their planters the following spring.

But few farmers scout their fields, either because of time or they aren't really sure what to look for.

Ellis and Hartman have also studied the use of sticky traps and have confirmed U.S. reports that if a trap catches an average 27 adult bugs in a week, the farmer should treat the corn the following spring. But that technique has little better future than scouting, Ellis says, since farmers aren't much more likely to check traps than scout fields. Ellis had higher hopes for egg monitoring, whereby a laboratory technician would check the number of eggs in a soil sample, and tell farmers whether to spray. After three years of research, Ellis and Hartman are giving up.

"Right now, farmers have to choose whether to use insecticide as an insurance policy, or to gamble that they won't be part of that 10 per cent that needs insecticide," Ellis says. "We were hoping for a more rational management system, but it doesn't look like we're any closer."

Bruce Hunter, research manager of Ciba Seeds, says his company and others are on the brink of releasing new hybrids that use a gene from a bacterium called Bt to produce their own insecticide.

"Corn rootworm is our next target," says Hunter, whose company will be the first to launch biotech hybrids this spring that use the Bt gene to make them resistant to European corn borer. Ellis fears that if most farmers plant hybrids with Bt resistance, the same thing will happen when farmers overuse their chemicals. "We'll be exerting tremendous selection pressure in favour of rootworms that can survive the gene," Ellis says. "The jury is still out, but the gene may be a very short term solution because the insect may quickly develop its own resistance."

Hunter says the company doesn't know how fast resistance will occur. "We know it's an issue...we know it's a possibility," he says. "We're funding a lot of research in this area." Ellis says until the answers are known, farmers should stick to their current emphasis on rotation. "What we're really doing is managing the population," Ellis says. "It's the best strategy."

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Revival in sight for sweetener industry

By MARIE CARTER Special to Farm & Country

Two current research and development projects into alternative crops may sweeten the pot for Ontario farmers.

Research is underway in Ontario to develop at least two new crops, stevia and chicory, for production of natural, low-calorie sweeteners and other products.

Leading the way is Tiverton-based St. Lawrence Technologies, part of the Kincardine-based Canadian Agra Group. In other countries, there is often government protection of the sugar beet industry.

Currently, the Delhi Research Station is involved with both Royal Sweet International Technologies and St. Lawrence Technologies in two separate projects to develop new all-natural, low-calorie sweeteners. Stevia is the subject of a "large program" begun in 1994, with staff from the Delhi Research Station and from Royal Sweet, says Jim Brandle, an Agriculture Canada researcher.

Chicory has been the focus of a three-year study of St. Lawrence Technologies.

Stevia naturally sweet
Leaves of the stevia plant, a perennial herb that grows to 50 to 60 cm in height, have been used as a sweetener for centuries by the Guarni natives of Paraguay. Stevia first came to the attention of Europeans in 1888 when it was discovered in the Paraguay highlands.

Stevia has been approved for human consumption in southeast Asia.

A stevia extraction process is being developed by Royal Sweet in partnership with the Alberta Research Council and the National Research Council; a processing plant will be built in Alberta in 1996. The refining process for stevia is chemical-free. The final product has many advantages, including stability. Because it doesn't break down with heat, it can be used in cooking; it also has an indefinite shelf life.

Stevia has yet to be registered for use in North America and Europe and it could be between three and five years before it turns up on store shelves.

Royal Sweet's preliminary trials for stevia began in 1994. The Tobacco Diversification Program has been involved in offsetting growers' start-up costs during the first year. Last year, 15 acres were grown in four-acre plots mainly in the Norfolk sand plain area - once prime tobacco country. "We hope to scale that up 10-fold next year," says Brandle.

The crop could be a boon to former tobacco growers looking for alternative crops. "Tobacco kilns for drying and the management skills necessary for transplanted crops are much the same," says Brandle. Stevia is planted using the plug system - much like tomato plants - making it an alternative crop for plug growers, as well.

Last summer's hot, dry weather was a challenge in growing many crops, including stevia. Nevertheless, says Brandle, "the growers did an excellent job and leaf yields of 2,800 kg per hectare [1.1 tonnes per acre] were achieved. Some problems were experienced with leaf spotting, but researchers have the problem in hand."

Plug plants of stevia were shipped to growers in mid-May and planted using a three-row transplanter set for 21-inch rows and eight-inch plant spacing. Land had been heavily manured to increase soil organic content. As well, 40 kg of phosphorus, 40 kg of potash and 60 kg of nitrogen per hectare (35, 35 and 53 pounds per acre) were applied. Some growers also side-dressed nitrogen. With no chemical weed control registered for stevia, the crop had to be cultivated mechanically and by hand. With the dry weather, up to seven irrigations were required.

Stevia was machine harvested in September. The plants were then dried in bulk (tobacco) kilns at 104 F for 24 hours. The leaves were separated from the stem by threshing and shipped for processing.

Cost of production has proven to be high, says Brandle, "but production research should decrease those costs over the next few years." Even so, he's optimistic that stevia can eventually be a cost-competitive alternative to the low-calorie sweeteners currently on the market.

Multi-purpose chicory
"Chicory is a particularly good opportunity for Canadian agriculture...we have a competitive edge over the U.S.", says Roger Cook of St. Lawrence Technologies. Production of chicory is well suited to southern Canada and northern U.S. "We obviously don't want to miss this opportunity for the development of a chicory industry here," says Cook. Chicory production has shown good income potential for farmers. In Belgium, one tonne of chicory earns a Belgian farmer 2,500 Belgian francs (C$113), compared to about 1,800 Belgian francs (C$81) for sugar beets.

Witlof or Belgium endive varieties of chicory have been grown as a salad ingredient for years. In St. Lawrence's current research, however, the plant's root is being refined and developed into two products: a high-fructose syrup similar to corn syrup; and inulin, a dry white powder and a natural carbohydrate, like starch, used as a food ingredient. Inulin is attracting the most attention, says Cook. It has tremendous potential and could eventually have as many uses as starch, researchers believe. The extraction of inulin would also make high-fructose syrup economically feasible as a by-product.

St. Lawrence researcher Chester Myers says inulin has potential as a "functional food" - a food additive that makes foods "good for you" by helping the growth of good "bifidobacteria" in the stomach and by adding fibre. Functional food health benefits cannot yet be claimed on Canadian packaging. But in Japan, where functional foods were "born", says one Agriculture Canada report, "the market trend for functional foods is constantly rising."

"It's phenomenal the number of phone calls we've received." says Myers.

Inulin also helps prolong shelf life. Ice cream, jam and yogurt with 10 to 12-per-cent inulin can withstand long preservation periods without any changes in taste or appearance. Inulin can also be used as a fat replacement in dietetic ice creams. Production of sorbitol, used in chewing gum, gelatin and chocolate, is also possible through fermentation of the raw inulin juice. Other inulin uses include food fibre and filling agents.

St. Lawrence Technologies began the chicory research and development project three years ago. Last year, traditional varieties of chicory such as Witlof and Magdeberg along with newer European varieties were grown in six experimental plots including August Sacher's farm at Rodney, and John VanDeWiel's farm at Drumbo.

"We're clearly planning to build a processing plant in Canada," says Cook. Eventually, it could take up to 7,500 acres to keep one processing plant running. No plans have been announced, however.

Researchers are now evaluating planting time and density, herbicide performance, time of harvest and equipment, and crop yield and storage.

"Generally, the crop is well suited to growing conditions [climate and soil types] typical of the test sites," says Cook.

St. Lawrence Technologies, with the support of the National Research Council and OMAFRA's Food Processing Research Fund, is also processing its chicory crop in a pilot plant to produce inulin powder and high-fructose syrup. The process is similar to sugar beet refining.

High-fructose syrup, when produced as a by-product, also has market potential. Currently, the baking and beverage industries use "commodity" syrups, usually corn syrup, as a sweetener. Chicory high-fructose syrup is 70 per cent sweeter than corn syrup.

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Crops and trees grow in European trials

By NORMAN DUNN Special to Farm & Country

Wheat and barley grown between rows of trees have been yielding more than crops in open fields in British trials.

The so-called silvo-arable system, with crops and fast-growing trees cultivated in the same fields, is planned for demonstration on farms throughout Europe. Researchers at the Department of Biology at Leeds University have been cropping winter wheat, spring barley and combining peas in rotation between rows of trees since 1990. Now, application has been made to the European Union to finance a Europe-wide project called 'Farming with Poplars' which will feature a series of 30-acre demonstration sites in England, Northern Ireland, France, eastern Germany, Hungary and Poland.

In the British trials, poplar trees have been planted every 20 feet, four inches in rows 32.5 feet apart. Because the trees occupy a 78-inch-wide strip of land, 26 feet remains for each crop alley. University of Leeds experts estimate that silvo-arable alleys should in future be at least 39 feet wide, and that 60 feet will be more suitable in the future to accommodate larger, high-capacity farm machinery.

At Leeds, the 1994 winter wheat harvest yielded four tons per acre under the silvo-arable system, or three per cent more than control trials of same variety wheat grown in the open fields. See Table 1. Last year, wheat yields were almost the same between the two systems, at 3.6 tons per acre. These yields were achieved with typical British fertilizer application on both systems of 133 pounds per acre, 46-per-cent N urea in spring followed by two dressings of ammonium nitrate of 222 pounds per acre and 89 pounds per acre respectively. No herbicides were applied in the autumn, but spring sprays included a Clormequat straw shortener mixed with Starane (Fluro-xypyr) and Harmony M (Thifensulfuron + Meta-sulfuron) herbicides.

Insecticides are used when required for the crops between the trees. But one advantage of a silvo-arable system is that the natural predators of crop pests can be encouraged along the tree strips.

The Belgian poplar hybrids are ready for harvesting at around 25 years when trunk diameter can reach 24 to 28 inches. Even in the north of England, growth in moist and sheltered conditions averages 6.6 feet per year. There is a good market for the timber for fruit and vegetable crates and pallets because poplar timber has little or no resinous smell to taint foods, says David Corry, silvo-arable research manager with the University of Leeds. Poplar timber is also pulped for paper making.

Corry adds that strips can greatly help with viability of growing poplars. Normally, with a final spacing of 26 X 26 feet, a stand of the trees in a pure forestry enterprise has about the same output per acre as our silvo-arable set-up at 20 feet, four inches X 32 feet, five inches, he says.

Even a few years of arable cropping among the young trees at the beginning can make the economics of tree growing on farm land much more attractive, he says. Without the crops income, the tree harvest would have to carry rent of land over 25 years, plus interest on the cost of establishing and tending the trees. Where the tree rows are more widely spaced, arable cropping can be carried on for longer.

Corry says establishing strips of trees across the fields lessens soil erosion risk. The tree root systems can also act as mineral scavengers, taking up excess nitrates from fertilizer given to arable crops and preventing excess run-off into ground water.

Norman Dunn is Farm & Country's European correspondent based in Ludwigshafen, Germany.