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A natural plant growth regulator that works

A simple seed treatment


November 14, 2007
By Rosalie I. Tennison

8aA simple seed treatment that would save seed growers money and still give them
the desired results sounds too good to be true. But, such a product exists,
the drawback is it is not registered for potatoes in Canada. The reason for
that is economics and marketing. This simple plant growth regulator is so inexpensive
and effective that it is not worth the expense to register it or incur the inevitable
expenses of packaging and marketing once registration is achieved. So, what
could be an economic boon for growers is a marketing flop for manufacturers.
However, late in 2005, one researcher reports that an application has been made
to PMRA to register the hormone, but that is still no guarantee of availability
in the near future.

The product is gibberellic acid, a naturally occurring phyto-hormone that is
used in the US for seed potatoes and many orchard crops and is not registered
in Canada, except for cherries. According to Dr. Loretta Mikitzel, who has worked
with gibberellic acid for about five years, if Canadian seed potato growers
could have access to it, they could reduce their management costs. "Growers
can manage size by planting closer together or plant larger seed pieces to encourage
more growth," she says. "But, these methods increase management costs
because more seed is needed. Gibberellic acid can be applied as a seed piece
treatment and it will moderate tuber size naturally. The best part is that it
is inexpensive."

Gibberellic acid is a natural plant growth regulator that, once applied to
the seed, will increase the number of stems and tubers, resulting in smaller
tubers. Mikitzel tried the acid as a dry compound mixed with water and then
sprayed it on the seed pieces to ensure even coverage. She tested it on nine
different varieties and noticed some variance in the results between varieties,
but always the results were positive. "As long as there is a percentage
increase in the results," she says, "it pays." She noted that
the size of the potatoes were shifted downward by at least one ounce which would
be a valuable result for any grower.

Mikitzel also tested the compound at increasingly higher concentrations and
determined that, if used at the recommended rates, there is no carryover. She
admitted there is carryover when the acid is used at the highest concentrations,
but, she adds, those rates are exponentially higher than any rate that a grower
would need.

In Manitoba, Blair Geisel of Gaia Consulting has also been working with gibberellic
acid. While his approach is slightly different, his results closely matched
Mikitzel's. "We had to adapt our method of application to meet the needs
of commercial growers," he says. "We found that not all varieties
respond in the same way, so, if it becomes available to growers, some study
would have to be completed to determine the effective rates for each variety."

Again, the downside of this good news story is that growers cannot get their
hands on it. Mikitzel suggests that grower pressure could convince a manufacturer
to package the product in useful quantities. Gibberellic acid is a compound
that needs to be packaged and it is not something that is readily available
in gardening stores or from an agri-retailer. Despite its potential, this simple
growth regulator is not available and hundreds of seed growers are missing an
opportunity to save some money on crop management.

Geisel suggests gibberellic acid has many applications beyond the seed industry.
There is a demand for small potatoes for the table market and gibberellic acid
could help maintain the desired small size. It also could keep varieties, such
as Shepody, to a uniform, manageable size for the French fry industry. "There
are many applications for this product in all areas of the potato industry,"
he says. "It's so useful because it doesn't affect yield, it just gives
a smaller size profile. It's a useful product that is effective and the price
is right."

Until the proposed registration application moves through the system and approval
is received, this useful tool remains on the shelf. Researchers who work with
it believe gibberellic acid offers growers high value at an economic cost, but
growers cannot get it. Pressure from the folks who need it most might help speed
up the process but, in the meantime, it sits on the shelf. -30-


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