Try growth regulators to prevent lodging

For European farmers, growth regulators are standard practice to help reduce the incidence and severity of lodging.

Growth regulators are designed to limit the internode elongation of plants by reducing the extension of the cells — in other words, to shorten the growth habit of the crop. This strengthens the straw, which helps improve standability.

Growth regulators have, to this point, been used more extensively in Canada’s horticultural industry for applications such as keeping ornamental nursery stock short and bushy rather than tall and leggy, to better suit the tastes and requirements of home gardeners.

The Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) is now studying adapting the use of growth regulators for use in wheat. After only one year of trials the results are still inconclusive but encouraging, says Peter Johnson, a cereal crop specialist with OMAFRA who is heading up the research. “What I will say is that if the growth regulator works properly it will only shorten the crop about three to four inches at the most or about the length of the head,” he says. “It doesn’t always shorten the crop, but what is intriguing is that even when it doesn’t shorten the crop, it will thicken the straw. So you can have a crop that doesn’t look like you have done anything to it and it will still stand better.”

Johnson doesn’t expect growth regulators to be the complete answer to the problem of lodging. If there is excessive nitrogen the crop will lodge even with the use of growth regulators, but Johnson does feel that there is lots of scope to play around with application rates to help reduce lodging potential in most situations. Future trials will focus on fine tuning growth regulator applications with nitrogen rates to achieve optimum results under different conditions.

Johnson doesn’t see any impediment to using these types of products under prairie growing conditions. “These products are used in Finland and other northern climates, so as far as latitude and the shortness of the growing season is concerned, I doubt that would have any impact on the effectiveness of the product for use in Western Canada,” says Johnson.

Many different generic brands of growth regulators are available in Europe and elsewhere, but for his trials Johnson is using the two brands which are currently approved for use in Canada. The first product, Cycocel (also known as CCC) has chlormequat chloride as its active ingredient and is currently registered for use on wheat, but with varietal limitations on the label. The other product is Ethrel, which contains the active ingredient ethephon.

Ideally, Cycocel is applied just as the growing point is above the ground or when the plant has around five leaves. Nighttime temperatures need to be above zero C. It can be applied later, up to the second node stage, but will be less effective. Ethrel, on the other hand, is applied later — at the flag leaf stage, but conditions cannot be excessively warm, as when the temperature exceeds 28 C there is a significant risk of phytotoxicity in the plant.

The high cost

A big impediment to widespread use of growth regulators at the moment is cost. To use Cycocel at its recommended one litre per acre rate currently costs around $38 to $40 an acre, making it cost prohibitive, even at the half litre rate which Johnson believes would be acceptable under Ontario conditions most of the time. In Europe the same product competes with many generic versions and costs around $5 per acre. Johnson believes that once generic versions become commercially available in Canada, the product will become more attractive for farmers.

“The patent is off chlormequat chloride and therefore generic products could be brought in and labelled here. There is at least one and perhaps two companies working on that very thing,” says Johnson. “These companies are looking at the cereal market rather than the horticultural market because it is a much larger market. There is a pretty good chance that the price per acre will drop dramatically if they are successful in getting those products here and labelled for use here.”

Increased combine speed

A small number of Ontario farmers are already using growth regulators on their wheat for another reason, says Johnson. “We do have growers who swear that if you use the growth regulator the crop will combine easier, just because it has that resilience and it doesn’t break up as much in the combine, so you have a little less challenge separating the grain from the straw,” he says. “I haven’t done any work to support that from a scientific standpoint but I do know some growers who say that is the main reason they use a growth regulator, because they can combine more acres per hour.”

So, although there is still much fine tuning to be done, some Ontario farmers are already using growth regulators and interest is growing. “We have gone from a standard N rate of 90 to 100 lbs. to 120 to 130 lbs., and are looking at going to 150 lbs. N/ac,” says Johnson. “We’re trying to push wheat production here in Ontario, just to keep it somewhat economically competitive with corn and soybeans. And the only way to do that is to increase N rates and as soon as you increase N rates then lodging becomes an issue. So farmers here are tremendously interested in these products.” †

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