E-Delivery

- Courtesy of Saskatchewan Pulse Growers Vankosky explained: "Effec veness of insec cide seed treatment depends on the popula on density of the pea leaf weevil and when they arrive. If there are too many of them, they may overcome the protec on. However, our preliminary data from an experiment in Swi Current, Saskatchewan showed good yield protec on from seed treatment, so that is promising." From an economic standpoint, Vankosky noted that the nominal threshold for pea leaf weevil is to consider spraying a foliar insec cide when 30% of plants sampled in a field have feeding damage on the terminal leaves. Cutworms and Wireworms Two of the biggest pest threats to pulses are cutworms and wireworms. "Both can lead to stand reduc ons and if the stand is too thin, yield reduc ons may occur," said Sco Meers, Insect Management Specialist - Pest Surveillance Sec on with Alberta Agriculture and Forestry. Wireworms One pest causing a lot of concern is the pea leaf weevil, an insect with a geographic range that continues to expand across the Prairies. Two of the biggest pest threats to pulses are cutworms and wireworms. Both pests differ in the approach needed to address them. Although cutworms are found throughout the Prairies, wireworms favour the Dark Brown soil zones in the dry, southern parts of Alberta and Saskatchewan. Neither pest is a welcome sight for producers, but cutworms are of greater concern to pulse growers. "Cutworms usually cut the plant off just below the soil surface," Meers said. "Wireworms are more likely to target the seed itself, and since pulses tend to be larger-seeded, the damage is o en less severe than with cutworms." The two pests also differ in the approach needed to address them. "Wireworms like cereal crops the best, so if there are cereals in a grower's rota on, they should watch for wireworm damage in one year to predict damage in the next," explained Dr. Haley Ca on, Research Scien st – Cereal Crop Entomology for AAFC. Seed treatments containing neonic insec cide offer some protec on against wireworms and aid in crop establishment. "The treatments do not kill the wireworms, but stun them for a few weeks or months, giving enough me to get a crop off that year," Ca on said. On the other hand, no such protec on exists for peas plagued by cutworms, though Meers suggests a foliar applica on of insec cide to manage the cutworm popula on once it appears. As for the threshold dilemma, Meers said that decisions should be based on when plant stands fall below acceptable levels. He suggested consul ng the Cutworm Pests of Crops on the Canadian Prairies field guide from AAFC for more informa on on cutworm thresholds. Dealing with soil pests is no easy task for pulse growers, yet it is well worth the effort. The longer pests s ck around, the more damage they do. P U L S E C R O P N E W S S U M M E R 2 0 1 8 | 3 1

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