MELFORT, Sask. – Plenty of creatures make a living from farmers’ crops besides farmers. The trick is knowing which ones are there and whether it is cost effective to remove them.
“It comes down to crop scouting; not spending money treating when you don’t need to, spending when it saves your crop or increases your yield,” said Jim Bessel of the Canola Council of Canada.
He told farmers at a canola council field day crop scouting should begin before the field is planted.
“If you soil test, are you using a moisture probe? Knowing how much water you have gives the criteria to plan your fertilizer and yield potential.”
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The canola council is developing a crop diagnosis sheet that will give producers a quick reference for crop development problems from insect damage to fertility problems.
Julie Soroka, an insect pest specialist with Agriculture Canada, said producers should assemble a crop scouting kit in the winter.
“Insects are always easiest to control in December,” she said.
“Anticipating a problem using forecast maps and preparing is more than half the battle. There is nothing worse than spending time putting together the kit when you should be in the field looking.”
The kit should include items such as field quides for insects, diseases and weeds, collection vials, plastic tubs with lids, plastic bags for insects, paper bags for plant samples, trowel, a metre or quarter metre measure or hoola hoop.
Time of day and weather conditions are critical to finding insects in the crop canopy with a net.
“Between 10 (a.m.) and noon and from two to four (p.m.) for most will let you establish populations in crop.”
Soroka said the technique to capturing insects is important.
“Stride quickly with each pass of the net,” she said as she walked quickly through a plot at the federal research farm, swinging her net.
Bessel agreed, telling producers never to be hesitant when sampling with a net and to take a deep “back-swing, as if you were on the golf course.”
Move quickly and make a full stroke to ensure the insects don’t move out of the way of the net, he said.
Soroka said the sampling pattern is also important.
“Make X patterns, M patterns or W patterns in the field,” she said.
“They make sure you are checking not just the edges but the centre and some random zones too.”
Cardboard or plastic cards that are made sticky with Tangle-foot and placed on wire spikes at the crop’s edge can provide an early warning that insects such as lygus bugs, grasshoppers and flea beetles are moving into a crop.
It doesn’t work as well with insects such as diamond back moths, aphids and flea beetles that are more likely to randomly spread in the crop.
Bertha armyworm larvae can be tough to count in a canola crop. Bessel recommended liberally spreading white flour over the crop canopy and thoroughly shaking the plants in a one sq. metre area.
“The worms will fall off, coated with flour and move around and be white on the ground and easy to count,” he said.
Crop damage is often the first sign of trouble.
Bessel said cutworm damage can be differentiated from wireworms by the jagged shredding that wireworms do to stems and leaves.
“Cutworms tend to hang around in warm, dry soil on south-facing hillside slopes,” he said.
“If you’ve tried the sweep net and checked your traps without seeing threshold populations of insects and your crop is still suffering, then start pulling them up and checking their roots. Something may be attacking from the soil.”
Burying severed pop bottles in the field with baits such as bran, potato or oatmeal will attract many ground-dwelling pests.
One-quarter metre measures are often more practical than metre measures.
“A sq. metre is a lot of space if you have to count fast-moving insects like grasshoppers,” Soroka said.
“Just use a one-quarter sq. (metre measure) and multiply by four.”
Disease scouting can often provide options for treatment to minimize losses.
Randy Kutchar, a disease specialist with Agriculture Canada in Saskatoon, said disease prevention starts early.
“Start in December. Make rotational and cultivar choices that will make your crop resistant to problems that are out there already,” he said.
He recommended choosing a blackleg-resistant Argentine variety.
Sclerotinia damage can be spotted on canola leaves as the leaves ball up at the edges. In sunflowers, the heads or stems may show signs of a white mould. Infections of the roots may cause wilting.
In July the sclerotinia apothecia mushrooms can be found in damp soil.
Crop scouting can also detect fertility deficiencies.
Stewart Brandt of Agriculture Canada in Saskatoon said nitrogen and sulfur deficiency can be spotted initially as poor crop colour and poor flowering. Sulfur shortages are often confused with diseases.
In canola, pale flower colour and reddish leaves are telltale signs of sulfur deficiency. A leaf sample can be sent to a lab for testing.
Applications of additional sulfur in concert with an appropriate balance of nitrogen will generally solve the problem.
