Tips to help corn growers fight disease and boost yield

Where you live in Ontario paints a picture of how your 2018 corn harvest played out. If you farm west of Toronto, you probably want to talk about something more pleasant — like a root canal.

Last year’s wet mid-season weather in southwest Ontario contributed to well above average levels of fusarium graminearum that causes gibberella ear rot (GER) in corn, and which led to well above average vomitoxin, or DON levels.

In a normal year, DON levels could range anywhere from zero to six parts per million (ppm), however certain samples in 2018 showed 10, 20 and, in rare instances, 50 ppm. Government data from early February showed that 3,000 damage reports were filed and $25. 5 million had been paid out in various production and salvage claims related to corn.

Looking ahead to 2019, it’s a level planting field again and producers have reason to be optimistic. Information sharing about what has and hasn’t worked is a fantastic tool for hybrid corn producers, according to Dale Cowan, senior agronomist and sales manager with AGRIS Co-operative, an Ontario-based company that provides agricultural innovations and solutions to its clients.

THINK DIFFERENTLY ABOUT FUNGICIDE APPLICATIONS

“We know which (corn) hybrids are susceptible,” he says. “Avoid them or grow them in limited acres up to the level of risk assessment.”

Cowan says producers should also aim for crop uniformity as later-emerging corn may be susceptible to GER, causing high DON levels. A healthy plant program will mitigate risk and can be accomplished through well-timed fungicide applications. According to Cowan, using a fungicide program has reduced instances of DON caused by GER by up to 50 per cent. “It won’t eliminate it, it will suppress it.”

For example, the current school of thought is to target fungicide application in corn just prior to tassel emergence, around mid- to late-July, with a Group 11 fungicide if leaf disease is visible or predicted to become an issue. What Cowan suggests is using the option to apply a Group 3 fungicide at silk emergence, around late July or early August, which is said to be the best protection against GER. This will also provide you with some foliar disease protection.

Given those options, the question is: Is it possible to combine the two modes of action into a one-application solution? “We’re looking at combinations and mixing the two classes together,” says Cowan, adding that research conducted during 2019 may help producers determine the best possible application timing for future crops.

WEATHER MATTERS

While many equate late planting dates to no DON, Cowan says that’s just noise. “Planting date doesn’t have anything to do with it,” he says. “It’s all about the weather at flowering or silking, and your hybrid choice.”

Derek Freitag, a market development lead for eastern Canada with Bayer, tends to agree that a watchful eye mid-season may be the key to a successful year.

Freitag says that targeting the plant at silking for ear rot and DON will make a positive difference, but at the end of the day, the biggest potential barrier to a successful corn crop is a favourable disease environment.

A key recommendation is to scout different hybrids from suppliers, note their various sensitivities and select a mixture of hybrids with various fusarium tolerance levels (he says he’s seen as many as five at one farm), then plant them at various times to spread the risk.

Freitag says another strategy is to maintain a healthy crop rotation. “Corn yield will be better if you’re doing wheat/ soybeans,” he says. “That’s probably the best rotation, but will introducing more crops lessen GER? I don’t think so, but your highest risk is going to be corn on corn.”

Make sure that your planter is set up for even depth for the most uniform emergence and look for opportunities to have the best possible stand establishment by working with your agronomy provider. “There’s a lot of tools out there, we have to look at all those tools from planting all the way to harvest,” he says. “It’s not ‘plant it and forget it.’ There are many things to do.”

THE POTENTIAL OF COVER CROPS

One of those things some producers are exploring, including Blake Vince, is cover cropping. The Chatham, ON producer is a genuine cover cropping evangelist and his 2013 Nuffield Canada thesis, Conserving Farmland With Cover Crops and the Importance of Biodiversity, centred on the positive effects of cover crops and biodiversity in various agricultural settings.

At his farm, 2018 was business as usual and he had no issues with DON in corn, while many nearby suffered. He planted his corn directly into a cover crop blend that included kale, hairy vetch, cereal rye and purple top turnip. He believes this agronomic practice is a primary reason his corn crop was below 3 ppm DON with zero downgrades at his elevator.

“I’m working to perfect a system of planting corn into living green cover crop,” he says. “As I walked across the field, the ears were hanging straight down, and the husks were open. When ears hang down, moisture doesn’t accumulate and grain toxins are not as likely to develop.”

Vince observes that producers hold physical grain yield as the No.1 success factor while, in his mind, financial yield should be the primary objective, even if that means lower actual grain yield. To achieve this goal, he thinks it will require a dramatic shift in thinking to help bring back greater soil diversity and ward off issues such as DON.

“No soil was formed with a collection of monocultures,” he says. “It was formed with a collection of diversity of plants and grazing animals. We’re trying to get away from monocultures in this diverse cover crop blend.”

Vince believes a greater diversity of hybrids will make everything better, which is why he currently imports 95 per cent of his seed from the U.S.

His best advice is for producers is to get as much information as possible. “The farmer’s best tool is to ask the tough questions to seed suppliers and their peer groups as to what hybrids they’ve had the most success with in 2018 and if there were any trends,” he says.

2013 Nuffield Canada thesis, Conserving Farm Land With Cover Crops and the Importance of Biodiversity, by Blake Vince: www.farmforum.ca/covercropthesis