Fungicides handle disease, improve overall plant

Pyraclostrobin credited | Trials show the ingredient boosts plant growth and yields

Fungicide use in Western Canada has grown exponentially in the past five years, says BASF, partly because of the side benefits of modern products.

The primary strength of fungicides such as Headline remains disease control, but researchers are now able to measure some of the additional perks, such as increased plant growth efficiency and improved stress tolerance.

“The product only stays in the plant for two to three weeks, but you see an enhancement in growth, primarily root system and leaf system,” said Russell Trischuk, technical marketing specialist with BASF Canada.

“That change in architecture actually just leads to a more robust plant that can manage periods of stress more effectively.”

Pyraclostrobin is the active ingredient in BASF’s Headline and related products. Growers who used it on their canola crops in the early 1990s started commenting on how green their plants were compared to untreated fields.

BASF researchers discovered that pyraclostrobin boosted production of the nitrate reductase enzyme in plants. It is the enzyme that converts nitrate products such as urea and anhydrous ammonia into a nitrite form that plants use for amino acid production, which ultimately results in protein production.

The company sees a 40 percent increase in nitrogen use efficiency in a laboratory setting in plants treated with pyraclostrobin versus untreated plants.

The treated plants have increased leaf size, stem thickness and overall biomass.

“In the field, we see probably a 15 to 20 percent boost in nitrogen utilization,” Trischuk told a recent Saskatoon stop on BASF’s Knowledge Harvest tour.

However, he said that doesn’t mean growers should consider cutting back on nitrogen fertilizer application when using fungicides.

Trischuk said nitrogen is one of the main building blocks for plants. The other is carbon, which comes from photosynthesis.

“When you use pyraclostrobin, we can actually show that you are more effectively and more efficiently converting the same amount of energy to more sugar,” he said.

BASF research has found a 20 percent boost in photosynthesis in corn when using Headline and an even greater increase when using Priaxor, a new fungicide the company expects to launch next year.

The company is still working on the data for canola, but Trischuk expects similar results.

Increased nitrogen use and improved photosynthesis doesn’t result only in more robust plants above ground.

“We see a very dramatic increase in the size of the roots as well,” he said.

“Everybody drives by their fields and they look at the top 48 percent of their (crops) and they kind of forget about the other 52 percent that is under the ground.”

BASF trials in 91 canola fields in 2012 and 2013 determined that the company’s fungicides resulted in 12 percent taller plants, with 20 percent more pods, eight percent fewer aborted pods, eight percent more leaves, 15 percent thicker stems and 10 percent longer roots.

All those growth efficiency factors add up to improved yields.

“We’ve had well over 200 trials over the past four years, and we’re at about an average of a three bushel (an acre) increase in this product with canola,” said Trischuk.

However, the big benefits come from improved stress tolerance.

Nitric oxide, a byproduct of the nitrate-to-nitrite conversion process, is a strong inhibitor of ethylene, a hormone plants give off that leads to chlorophyll degradation and ultimately death.

The nitric oxide helps a plant better cope with drought, excessive heat and flooding and also helps it reach its genetic potential for days-to-maturity.

Pyraclostrobin also boosts the levels of superoxide dismutase, which is an enzyme that helps plants cope with oxidative stress.

The bigger leaves and longer root system associated with the product also help plants deal with flower blasting by giving them more access to water to cool down.

Growers in field trials have reported as much as an 11 bu. per acre yield increase under drought conditions when treating canola with pyraclostrobin compared to un-treated fields.

Franck Groeneweg, a grower from Edgeley, Sask., said farmers are inundated with ads extolling the benefits of fungicide treatments, and he has experienced tremendous results using the product on his flax crops.

“We’ve seen some amazing benefits to applying one pass of Headline at early flowering,” he said.

Groeneweg said he has been getting an extra 10 bu. per acre using Headline.

“The difference is so large and so predictable,” he said.

However, the benefits with other crops seem to vary from year to year depending on environmental conditions.

“I’m not sure we saw the (same) benefits of fungicides this past year as we did in 2012,” he said.

“It was not real apparent where you sprayed and didn’t spray. There might have been a yield gain, but it was not like 2012, where the difference was huge.”

Groeneweg said he is nervous that over-use of products such as Headline will lead to fungicide resistant diseases like those seen in the European Union.

“Over time we’re going to make these active ingredients basically useless,” he said.

Trischuk said it is one of the most common comments he hears from growers, but he assures them that fungicide resistance isn’t nearly as big a concern as herbicide resistance.

It’s because most of the major diseases in Western Canada are specific to certain crops, so growers can get away with using the same mode of action in the same field because they are selecting for different diseases in different crops every year.

BASF still takes precautions to prevent resistance, such as creating fungicides with multiple modes of action, developing sustainability guidelines for growers and advising growers on labels to use only one application of a specific fungicide in a crop per year.

The ideal time for applying BASF fungicides is the two to six leaf stage of development in canola, the flag leaf stage in cereals and the 10 to 30 percent flowering phase in pulses and flax.