Tissue tests are money well spent for growers who are unsure if their crop needs more nutrients, says John Heard, a soil fertility specialist with Manitoba Agriculture.
“If (it) looks like there’s some ailment, you should do a complete diagnostic evaluation, which generally includes a tissue test and a soil test,” he said.
Farmers Edge, an agriculture consulting firm, started conducting in-season tissue testing at its lab in Winnipeg this spring.
Marketing manager Brad Ewankiw said it is a tool that can help growers troubleshoot problem areas in their crop.
“If they have a cereal crop and there are areas that are yellowing or doing something odd, they would be able to take some samples of the leaves and potentially identify the deficiency.”
The service is in its infancy, but Farmer’s Edge has already received tissue samples from across Western Canada for canola, corn, alfalfa and wheat, said lab operations manager Laura Cross.
The company charges $45 for a complete analysis of a tissue sample and says turnaround time is three days from sample submission.
Heard said Manitoba growers sometimes try to save money by sending a sample to the province’s Crop Diagnostic Centre for a free visual diagnosis.
However, he said the diagnosis can be uncertain and inexact because a visual inspection only tell so much.
“Yeah, it’s yellowing. Maybe it’s nitrogen, maybe it’s sulfur or maybe it’s something else,” he said. “People have to be willing to pay to get the answers sometime.”
Heard said a yellow or damaged plant doesn’t always indicate a lack of nutrients in the soil.
“Just the other day I took some tissue samples from a field and found out it was probably herbicide injury,” he said.
“But a soil test might say that there’s enough (nutrients) in the soil. (So) it’s not a problem where the plant needs to be supplemented, it’s a case where another type of injury has caused the symptoms to appear.”
He said testing is also beneficial because of growers’ tendency to assume yellow crops are nitrogen deficient.
“But in the last few years we’ve observed a lot more cereals and corn coming back with sulfur deficiencies.”
As well, said Ewankiw, a tissue test can provide information on what’s happening right now.
Heard cautioned that tissue tests can provide an incorrect diagnosis if plants are in extremely wet soil.
This year, crops in Manitoba and southeastern Saskatchewan are turning yellow because they cannot absorb nutrients in the soil. A tissue test might indicate a nutrient deficiency when, in fact, the soil has sufficient nitrogen.
“Don’t take a tissue test now because, guaranteed, things are going to be lacking or deficient,” Heard said.
“When soils are waterlogged, even though the nutrients are there in the soil, the plant doesn’t take them up.”
