Corn earworm migration is not predicted in the next five days. A persistent and locked-in northwest to southeast flow weather pattern is predicted to hold through at least next weekend, and should keep any migrating corn earworm moths to the south of the corn-growing region through that time. Growers are advised, however, that larvae are present in some fields as a result of earlier moth flights this summer so continued scouting is encouraged especially in fields where the crop stage is at a susceptible stage to damage.
Western bean cutworms continue to emerge and progress through their annual flight in select areas of the corn-growing region. Not all fields are seeing western bean cutworm pressure this year, but there are areas that are seeing rather high pressure with high moth presence and egg laying. High risks remain across northern Indiana where moth counts remain high and where active egg laying and hatching is ongoing in crops at critical growth stages. Moderate risks also continue in the forecast across northern Kansas and much of Nebraska as well as western Iowa where scattered high moth counts and egg laying persist. Additional Moderate risk areas are in Wisconsin where the moth flight is likely entering its peak now but where moth counts, as a whole, are not as high in comparison to previous years or other regions of the Midwest. Moderate risks continue across the northern half of Indiana and northern Ohio and have been expanded further north into southern lower Michigan where moth activity should pick up in the next week. Low risks remain across much of the Great Lakes region and into southeast Canada. So far, moth captures in Canada are much lower than previous years so only Low risks are predicted in these areas but counts will be monitored closely. Growers are advised to monitor not only moth counts but also egg laying/hatching in fields and take appropriate action, if necessary, where threshold values are exceeded and where crops are at susceptible stages to damage.
Corn rootworm risks remain in place through the next week across much of the corn-growing region. Any remaining hatch risks should be confined to the far northwestern portion of the corn-growing region (North Dakota and perhaps far northwest Minnesota), with beetle emergence and presence risks continuing across the remainder of the corn-growing region in the next week. Continued field reports of beetle presence and root pruning are coming in from scattered locations across much of the Midwest with some beetle counts exceeding threshold values in some areas. Growers are advised to continue to scout both their corn and soybean fields and assess not only beetle populations but also dig up or pull corn plants to check root status and feeding damage. If roots are hairy and the plants do not pull up easily, corn rootworm problems may be more minimal. If beetle counts are rather high and root pruning is present, you may need to consider a change in your planting practices next growing season.
Soybean aphid risks remain in the Low category for the next week. Overall, field reports continue to indicate either no or very low soybean aphid populations with only extremely isolated cases of higher population densities across the upper Midwest and Great Lakes region. The presence of natural predators has helped suppress soybean aphid populations in some fields where they are present. With soybeans in critical reproductive growth stages across the majority of the region, growers are advised to continue to actively scout fields and monitor for the presence of soybean aphid. If present, watch for population changes and also for any natural enemies that may inhabit the field as well. Weather conditions are predicted to stay rather favorable for potential soybean aphid regeneration in the next week so populations, where they exist, may increase in some areas this week. It is also recommended to make any treatment decisions based on what is occurring in your fields versus what the regional report may be saying as soybean aphid populations are rather hit and miss this year but some locally high populations are present in isolated areas.