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Crop advisor’s casebook: What’s chewing on these chickpea roots?

A Crop Advisor's Solution from the December 4, 2018 issue of Grainews

Logan Skinner.
photo: Supplied

Late May last spring, I received a call from Warren who had some questions about chickpea emergence.

Warren owns a mixed grain farm near Big Beaver, Sask., where he grows Kabuli chickpeas, red lentils, canola and durum. He was concerned about his chickpea crop — some areas were not emerging as well as others a few weeks after seeding.

At Warren’s chickpea field, I discovered some areas had adequate plant stand densities with healthy chickpea plants at the three- to six-node stage. However, some patches of the field were bare, with zero seedling emergence.

“Does this look more like herbicide damage or germination issues to you?” he asked me.

We’d have to look at both factors, and I’d also add fertilizer burn to the list of potential injury sources.

With respect to germination, the seed test performed prior to seeding revealed sufficient germination and no disease present.

Warren had seeded at the correct depth, and into adequate moisture. In fact, the region experienced good conditions for germination early in the year.

We dug for seeds in the bare patches to examine them for germination. We found multiple shoots coming from a single chickpea — and the shoots were shredded like they had been chewed.
photo: Supplied

Herbicides were applied at the appropriate rate and timing. In addition, no residual herbicides that could cause chickpea injury were applied to the field in the past two years. Finally, the areas of poor emergence were scattered randomly throughout the field, and not in any pattern as we would expect to find if the issue was caused by herbicide injury.

Neither was the issue fertilizer burn, as Warren followed the guidelines set out by the Saskatchewan Ministry of Agriculture for safe rates of seed-placed phosphorus.

As I was walking from a patch of bare soil toward some healthy plants, I noticed the odd plant was wilting and dying. Warren and I began digging for seeds in the bare patches to examine them for germination. We found multiple shoots coming from a single chickpea — and the shoots were shredded like they had been chewed!

We were dealing with an insect problem, but which pest was eating Warren’s crop?

Crop Advisor’s Solution: Scout early in the season to look for cutworm damage

After ruling out herbicide injury, germination issues and fertilizer burn, Warren and I began digging in the soil of the bare patches for seeds. We found multiple shoots coming from a single chickpea, and those shoots had been shredded. Something was chewing on these shoots.

I had a hunch if we dug in the dirt at the edge of the bare patches where the chickpea plants had emerged, we might find the pest causing this damage.

As we searched the soil we finally found the insects responsible — cutworms! At the bare patch’s edge, we found cutworm populations well above the economic threshold feeding on the plants.

The following night, Warren sprayed an insecticide when the cutworms were actively feeding above the soil surface. The shoots inside the bare patches had enough energy to eventually emerge into a healthy chickpea stand.

This field’s yield was slightly lower than Warren’s other chickpea fields, however, he was still happy with how the crop turned out considering how it looked at the beginning of the year.

Start scouting fields early in the season, as crops are emerging, paying close attention to areas with poor emergence. And examine the soil profile for insects — damage from pests can occur below as well as above ground.

Logan Skinner works for Richardson Pioneer Ltd. in Coronach, Sask.

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