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Control the pasmo in your flax

Left untreated, the pasmo fungus can take five to seven bushels per acre from 
your flax yields. Luckily, farmers have effective fungicide options


Flax is an increasingly popular crop. With growing demand from Europe, the U.S. and China, flax is likely to stay in high demand (with attendant high prices) for the foreseeable future. It also produces a high profit per acre compared with grains and works well in crop rotations to break disease and pest cycles.

While flax grows well in Canada’s cool and wet climate those same conditions are also a great growth environment for funguses. One of the greatest fungal threats to flax in terms of yield loss is pasmo. Known scientifically as Septoria linicola, pasmo attacks the aboveground parts of flax causing circular brown lesions on the leaves and alternating green (healthy) and black (diseased) bands on the stem. The infected tissue is covered in tiny black fruiting bodies, which bear the spores of the fungus and spread it to other plants when conditions are right.

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Pasmo spores are dispersed by wind and rain and can overwinter in crop debris at the end of the season. High levels of rain and warm temperatures favour the disease and can cause it to spread rapidly through a ripening crop. This is particularly a problem in the harvest season in Canada.

There are ways to fight pasmo in your fields and to prevent it from being introduced if it’s in your area. You can seed early to avoid the high moisture conditions of the Canadian fall. You can also use clean, fungicide-treated seeds and wait at least three years between flax crops, especially if you’ve had an outbreak of pasmo.

However, three years between flax crops may be longer than you’re willing to wait. Farmers looking to grow flax more often need to consider broad spectrum fungicides.

The headlines on Headline

One fungicide that is proving highly effective against pasmo is Headline. Developed and marketed by BASF’s AgSolutions division, Headline is a systemic fungicide that can move through leaf and stem tissue, making it effective no matter which part of a flax plant it is applied to. It works by stopping spore germination, preventing an infected plant from infecting others, and keeping spores from taking root on a healthy plant. It also stops cell respiration in living fungal colonies, killing the fungus on infected plants. According to BASF, this produces increased yield because plants that are not fighting infections are able to devote more energy to growth.

That all sounds pretty good but just how effective is Headline? After all, no chemical producer will come out and say that a product of theirs is below par. We’ve had the benefit on the Prairies of several years of fungicide testing by the Indian Head Agricultural Research Foundation (IHARF). These trials tested various fungicides on flax in a range of growing conditions, with areas of each crop left untreated for contrast.

IHARF shared the results of their latest round of field studies with us. In years with heavy fungal infections Headline-treated flax showed very strong yields compared to untreated flax, in some cases as much as great a difference as five to seven bushels per acre. This was consistent with the results of previous years. The yield boost was strongest in the years of heaviest fungal infection, and less pronounced in years with lighter infections.

Based on prices we’ve looked at Headline costs around $15/acre per application, with two applications per year recommended for flax, coming to $30/acre per season. With a likely boost of five bushels per acre, and a bushel of flax selling between $11 and $15 in the past year, the average yield boost will more than cover the cost per acre.

Flax is a high-yield crop with consistently good prices over the last several years. To get maximum value it’s worth taking care to prevent fungus infections, from timing your planting to utilizing a fungicide like Headline.

About the author

Columnist

Michael Flood is a business writer and columnist. You can reach him at [email protected]

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