DON corn testing: A new era begins

After a disastrous vomitoxin outbreak, the Ontario Corn Committee is implementing a testing program that farmers have wanted for years. But will companies participate?

Ontario corn farmers have been relying on their own observations and those of their neighbours along with scant information from corn companies to make hybrid selections that lower their risk of vomitoxin.

When they go to make their selections for 2020, however, they will have new independent disease risk numbers on which to base their decisions.

The Ontario Corn Committee (OCC) is supervising a two-year project to evaluate the susceptibility of corn hybrids to Giberella infection, which leads to the presence of deoxynivalenol (DON), in the corn, which causes vomitoxin. The inoculated trials will hopefully include most of the hybrids grown in Ontario. The OCC is requesting seed companies enter their current and new hybrids in newly created inoculated trials for susceptibility to DON.

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Why it matters: There were extensive acres of Ontario’s corn crop adversely affected by the presence of deoxynivalenol (DON), which decreased the value and marketability of that corn, causing economic stress to farmers.

The committee says the voluntary trials will take place in both Ridgetown and Ottawa and are funded for the next two years.

Farmers have requested disease susceptibility trials for years through resolutions at grower meetings and in many conversations. Last year, in which DON infected a significant portion of the province’s corn crop and resulted in serious frustration for farmers selling the crop and grain handlers in managing and marketing it, hammered that point home.

One of the reasons that information has not been available before is that there has never been a year in which disease hit so many of the OCC’s hybrid performance trial locations. As a result, there is some hybrid susceptibility information already available on the 2018 crop at gocorn.net, the online home of the OCC trials.

Widely dispersed infection

There were several reasons researchers were confident in the reliability of DON-related observation in this year’s OCC trials, says Albert Tenuta, OMAFRA’s field crop pathologist.

  • Hybrid differences were consistent across plots across the southwest of the province. For example, if the infection level of a hybrid was high in Ilderton and Exeter, it was as well in Ridgetown.
  • The hybrid differences matched what growers reported in their fields.
  • Dave Hooker of the University of Guelph’s Ridgetown campus subjected the results to statistical analysis and found them significant.
  • The results are based on 1,225 samples across 136 hybrids at five locations.

As a result, the OCC, made up of growers, seed companies, government and academic representatives, unanimously decided to make the information available, said Tenuta.

The table found at gocorn.net will show a wide variety of susceptibility to DON, although most hybrids were in the middle of the evaluation range. Hybrids will be shown as red, yellow and green. Red indicated a higher level of susceptibility.

“It is important to note that none of the hybrids can be said to be ‘resistant’”, the OCC said in its statement. “Under conditions favouring Giberella, any of them can accumulate significant amounts of DON. However, the OCC believes that the information contained in this report will provide a tool to assist growers in reducing the risk of selecting hybrids that are among the most susceptible.”

Why inoculated trials?

Inoculated trials allow researchers to be sure that hybrids are subjected to exactly the same disease load, making the trials fairer.

Inoculated trials are being used in order to make sure each hybrid competes equally, the corn committee says in a release.

The hybrids entered in the trials will be tested based on two types of inoculation, including silk channel and wounding to simulate insect or bird damage.

There have been no independent evaluation of DON susceptibility conducted in Ontario using inoculated trials. The corn hybrids grown in Ontario have similar genetics to those grown in the rest of the continent, and especially the U.S. Midwest, but they are grown in the lee of the Great Lakes, which makes for different DON-risk susceptibility.

The trial results will be available for the committee to review in November 2019, and with approval by the committee, the results, including hybrid names, will be made public.

“While it is a seed company’s decision as to whether to participate in these tests and which hybrids to enter, the OCC is strongly encouraging them to enter all new hybrids in the DON trials along with any existing hybrids that they expect to continue to market for 2020 and beyond,” said the committee in its release. “It is important that the entries in these trials represent as large a proportion of the corn acreage in the DON-prone areas of Ontario as possible.”

Tenuta says the information is another tool for growers. With perfect conditions — as there were in many southern Ontario fields in 2018 — any hybrid will show some infection, but there are some hybrids that are highly susceptible.

Those are the ones that need to be eliminated in the market, says Tenuta.

There has been fusarium head blight susceptibility ratings for wheat varieties in Ontario for years. Fusarium head blight is caused by fusarium graminearum, which also produces Giberella, the main precursor infection to DON in corn. The result of being able to select the least susceptible varieties has been that the most susceptible ones have disappeared.

Being able to examine corn hybrid susceptibility data could also have an impact on the trend to farmers planting fewer hybrids. Maintaining a diverse hybrid number can help reduce impact of disease, says Tenuta. Another major factor affecting whether a plant is infected with DON is silking date. That can be varied by changing planting dates or hybrid maturities.

While the new testing project is funded for two years by the Ontario Ministry of Agriculture, Food and Rural Affairs, Grain Farmers of Ontario and entry fees from participants, the corn committee says it expects DON testing to be part of the regular Hybrid Performance Trials administered by the Ontario corn committee. The committee is made up of representatives from Agriculture and Agri-Food Canada, OMAFRA, the University of Guelph, the Ontario Soil and Crop Improvement Association, the Grain Farmers of Ontario and the Canadian Seed Trade Association.

About the author

Editor

John Greig has spent his career in agriculture journalism and communications. He lives on a farm near Ailsa Craig, Ontario. Contact John at [email protected] or follow him on Twitter @jgreig

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