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Wireworms are primary pests of potatoes in Canada. Presently, the highly toxic organophosphate phorate (i.e., Thimet 20G) is the only effective insecticide in use in Canada. As such, there is an urgent need for novel alternative treatments that provide competitive tuber blemish protection and wireworm reduction with a safer human and environmental portfolio. Herein we evaluated broflanilide, a novel meta-diamide insecticide for both tuber protection and wireworm mortality. When evaluated in field trials in Agassiz, British Columbia over 6 yr, broflanilide applied as a seed piece treatment (SPT) to mother tubers at 1.5-2.0 g AI/100 kg seed (approx. 50 g AI/ha), or as an in-furrow spray (IFS) at 0.23-0.25 g AI/100 m row (approx. 25 g AI/ha) was as effective at reducing blemishes to daughter tubers by wireworms (Agriotes obscurus) as phorate (Thimet 20G at 3230 g AI/ha), bifenthrin (Capture 2EC IFS at 300 g AI/ha) and clothianidin (Titan ST at 312.5 g AI/ha). In addition, broflanilide SPT and IFS applied at the above rates reduced resident wireworms (in the field at the time of planting) by 95.4-99.0% and neonate wireworms (produced from eggs laid during the growing season) by 98.1-100%. Similar results were obtained when broflanilide IFS (nonsystemic) was paired with clothianidin SPT (systemic) for broad-spectrum potato insect pest control. Strategies for the use of broflanilide on wheat (e.g., Teraxxa F4) in rotation with potatoes (Cimegra), both registered in Canada in 2020 are discussed., (© Her Majesty the Queen in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada, 2022.)

The efficacy of various insecticides and application methods in protecting potatoes from wireworm (Agriotes obscurus L.) damage as well as reducing wireworm populations was studied over 5 yr in Agassiz, British Columbia. Protection from wireworm damage was measured by the number of blemishes to daughter tubers, and effects on wireworm populations were measured by sampling soil around seed potatoes and/or by bait traps the following spring. Organophosphates registered for wireworm control in the United States and/or Canada (phorate and chlorpyrifos), significantly reduced blemishes to tubers by, respectively, 92.2 and 90.2%, and populations of large (> or = 9 mm long = 'resident') wireworms by 83.4 and 71.0% relative to controls. Similar reductions in smaller (< 9 mm long = 'neonate') wireworms were also observed. Neonicotinoids (imidacloprid, clothianidin, and thiamethoxam) tested as seed piece treatments at approximately 12.5 g active ingredient/100 kg potato seed reduced blemishes by, respectively, 19.1, 71.6, and 90.6%, but resident wireworms were only reduced by, respectively, 22.0, 29.1, and 51.8%. Significant mortality of neonates was not observed with any neonicotinoid treatment. With the possible exception of thiamethoxam, where significant reduction in resident wireworms occurred, it is likely that the blemish protection provided without significant wireworm mortality with imidacloprid and clothianidin treatments was because of long-term wireworm intoxication followed by population recovery. The phenyl pyrazole, fipronil, applied as an in-furrow spray reduced blemishes by 94.3%, and resident wireworm populations could not be detected in plots the following spring. Neonates were reduced by 93.3%, indicating excellent residual conotrol had occurred with fipronil. These studies indicate that tuber protection by fipronil and currently registered organophosphates is likely because of significant early season mortality of wireworms, whereas neonicotinoids generally provide control through long-term morbidity without high levels of mortality occurring.

Counts of green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), in potato, Solanum tuberosum L., fields were used to evaluate the performance of the sampling plan from a pest management company. The counts were further used to develop a binomial sampling method, and both full count and binomial plans were evaluated using operating characteristic curves. Taylor's power law provided a good fit of the data (r2 = 0.95), with the relationship between the variance (s2) and mean (m) as ln(s2) = 1.81(+/- 0.02) + 1.55(+/- 0.01) ln(m). A binomial sampling method was developed using the empirical model ln(m) = c + dln(-ln(1 - P(T))), to which the data fit well for tally numbers (T) of 0, 1, 3, 5, 7, and 10. Although T = 3 was considered the most reasonable given its operating characteristics and presumed ease of classification above or below critical densities (i.e., action thresholds) of one and 10 M. persicae per leaf, the full count method is shown to be superior. The mean number of sample sites per field visit by the pest management company was 42 +/- 19, with more than one-half (54%) of the field visits involving sampling 31-50 sample sites, which was acceptable in the context of operating characteristic curves for a critical density of 10 M. persicae per leaf. Based on operating characteristics, actual sample sizes used by the pest management company can be reduced by at least 50%, on average, for a critical density of 10 M. persicae per leaf. For a critical density of one M. persicae per leaf used to avert the spread of potato leaf roll virus, sample sizes from 50 to 100 were considered more suitable.

The effect of crop rotation on populations of tuber flea beetle, Epitrix tuberis Gentner, in potatoes was investigated using data supplied by an integrated pest management (IPM) company and Geographic Information System software and conventional statistical methods. Using combined 1995 and 1996 data, beetles of the overwintered and F1 generations in both the interior and edges of potato fields showed a significant linear increase with an increase in the preceding consecutive years (0, 1, and 2 years) that the current years' crop was planted to potatoes. Populations were significantly higher in nonrotated fields compared with rotated fields. Both the percentage of the cropping region requiring insecticidal control of tuber flea beetles and the cost of insecticides per hectare of potatoes grown increased linearly with an increase in the number of previous years planted to potatoes. Not practicing crop rotation resulted in a 4.2-7.3% increase in the cropping region requiring insecticidal control of tuber flea beetles. The cost of controlling beetles in potato fields planted to potatoes for 3 consecutive years was up to $20/ha greater than potatoes rotated from the preceding year. Beetle counts from the interior of rotated potato fields never exceeded threshold levels when field edges also were below threshold. It is concluded that sampling of overwintered beetles in interior sites of rotated fields could be abandoned, and only 1 monitoring scout rather than 2 would be necessary to monitor a field during this time. From these results, we concluded that rotating potato crops would reduce spray costs to the farmer and monitoring costs to IPM companies.