Scout daily for signs of fusarium

It is not time to start carving the tombstone for cereal fusarium, but a new fungicide might give farmers another tool.

Fusarium head blight is present in 60 percent of the wheat grown in Manitoba, 10 percent in Saskatchewan, and two or three percent in Alberta. The disease has crept along the darker soil zones from the Red River Valley, where it arrived in the late 1980s, to its most recent appearance in Alberta’s Peace River district.

Along the way, it has left a swath of discouraged farmers and frustrated agronomists.

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Manitoba agriculture estimates that fusarium has cost the western farm economy $30-$50 million annually since 1993 when an epidemic did more than $100 million damage.

But now farmers have a new chemical to help clear the blight.

Folicur by Bayer, registered under an emergency use permit applied for by the Manitoba and Saskatchewan governments, has been released this year for aerial and ground application.

Bayer director of sales for Canada, Stan Prokopchuck, said the Pest Management Review Authority granted the provinces’ request even though a full data package for the product was not yet complete because there was no other effective product and because the fusarium problem was so bad.

Gary Platford, a fusarium researcher formerly of Manitoba Agriculture but now self-employed, said during a presentation at the Western Canada Farm Progress Show in Regina last week that testing done by Manitoba last year shows Folicur reduced the incidence of fusarium-damaged kernels by up to 50 percent and cut the amount of vomitoxin by a third to half.

Fusarium spores arrive first by air or contaminated seed and are later spread through water splashing from raindrops and gusty winds. The fungus lives in plant debris at the soil surface and infects emerging seedlings. A percentage of the young plants die, cutting average stands and yields.

Later in the season, just after the head emerges from the boot and begins to flower, the disease strikes again. Spores stirred up by winds and rain and encouraged by damp conditions or heavy overnight dews come to rest in the vulnerable new cereal heads.

If daytime temperatures are in the 25 to 30 C range, the fusarium will rapidly infect the plant, indicated by its telltale pink coloured mould. At this point it is already too late.

Antifungal seed treatments will prevent the early plant deaths, but spraying is time sensitive. Folicur must be applied within a five-day window, however it is most effective in the two days that the anthers are visible in the middle of the head. At this point the head is newly emerged and only starting to flower.

Danielle Percival of Bayer said as a rule of thumb the fungicide should be applied “when you can grab 10 heads in one hand and one of them has begun to flower. Then go spraying. Go right now.”

Rain is the major factor in determining whether to spray. If rain is predicted prior to full emergence, when the head spikelets are just visible in the boot, then it is advisable to spray within three to four days.

As little as five millimetres of rain will trigger a spore release by the disease.

If it occurs anytime in the three days after head emergence, then the plant is susceptible. If the rain comes within five days of flowering or heavy dew or high humidity is present, fusarium will take hold of the crop.

Selecting fusarium-resistant wheat varieties can lower occurrence. If fusarium is present in the area, good crop rotations will help reduce incidence. Even green feed or silage production can be affected because the fungus will be present in the plant and with it, the vomitoxin.

“At this time of year continuous field scouting is necessary. Farmers will have to be on top of this every single day,” said Platford.

All surfaces of the head must be covered with the Folicur spray, so using the correct volumes of solution and the correct types of spray nozzles are necessary.

Bayer recommends a spray solution of 40 litres per acre for ground sprayers and 47 litres per acre for air application. Spray solutions should include 118 millilitres of Folicur per acre with a 9.5 litre jug covering 80 acres of crop.

A non-ionic surfactant needs to be added to the sprayer mix.

Either a double swivel nozzle holder or a single twinjet, twin flat spray nozzle is recommended by Bayer.

With the double swivel setup, one nozzle should face forward and the other backward. Each nozzle should have a Turbo TeeJet or flat fan nozzle with a 110 degree spray angle that is capable of delivering 0.15 US gallons per minute.

If a single twinjet, twin flat spray tip is used, the application should be made at 38-46 centimetres above the plant heads.