The beginning of summer presents Canadian potato farmers with another opportunity to grow this beloved vegetable. For many farmers, it is often a time when they also prepare for what’s to come throughout the growing season from June to September, depending on when the tubers were planted. For pests like the Colorado potato beetle (CPB), potato emergence from the ground means it’s time to eat potato leaves and reproduce. The presence of adult CPB and their eggs in potato fields may be observed as early as 14 days after crop emergence – with every stage of growth being observed by mid-growing season.
The presence of adult CPB does not guarantee that eggs are present. However, the opposite is true. CPB eggs may be considered as an indicator for the presence of adult CPB in potato fields even if the adults are not visible. Studies show that foliage loss on leaves due to CPB infestation may affect crop yield. Therefore, CPB pest control measures must be implemented when thresholds are reached. Thresholds refer to CPB infestation levels that would reduce the expected yield. Pest control is particularly important during bulking, which begins soon after flowering later in the growing season. This time is crucial for pest control as tolerance thresholds for the crop drops.
Different pest management strategies may be implemented to reduce the possible yield losses from CPB infestation. Some farmers plant insecticide-treated tubers that may resist CPB infestation without spraying for CPB throughout the season. Other farmers tend to plant early-maturing varieties to elude expected peak infestation levels that may prevail around July/August. However, most early-maturing varieties do not bulk as much as late-maturing varieties. Therefore, a farmer must decide which trade-off best suits their circumstances.
Crop rotation also helps reduce infestation levels from one season to another. Even though crop rotation is encouraged, it must be highlighted that not all farmers may have crop rotation as a pest control option. Natural enemies exist but barely lead to effective CPB control. When farmers exhaust the above-mentioned options, they often opt for pesticide application as a last resort crop protection technique. CPB pesticide resistance has been reported after application. Farmers tend to use whatever pesticide is effective from season to season. Most pesticides will be applied once or twice throughout the season, which may be enough for effective CPB control.
It is common practice for farmers to spray an entire field that has reached a yield threat limit. The assumption is that infestation may be in the whole field. This might be the case, but fields are usually toured and checked for infestation regularly so that CPB pest control is implemented in good time. My research is developing intelligent spraying systems that can assist farmers with spraying only parts of the field that are infested. This has potential to reduce pesticide quantities and also help reduce the likelihood of environmental contamination that may result from pesticide residues.
Photo courtesy of Humphrey Maambo
