Corn earworm migration risks remain in the Low category for the next five days as northwest flow is expected to dominate the weather through the weekend. A quick-moving low pressure system and cold front may bring an isolated migration threat initially to the Plains and western Midwest tomorrow night into Friday morning with the risk then shifting east and stretching from Kansas and Missouri northeast into eastern Iowa, Illinois, southern Wisconsin, Indiana, southern lower Michigan, and western Ohio by Friday night into Saturday. The source region should be focused across Texas and Oklahoma so any moth flights should remain isolated with this cold front. Once the cold front passes, no migration risk is predicted as northwest winds and cooler weather return once again to much of the corn-growing region. Growers are advised, that despite the lack of recent migration events, there are still reports of corn earworm larvae causing damage in many commercial, processing, and fresh-market fields as well as specific vegetable crops across the corn-growing region so scouting remains important as earlier moth flights this summer are now advancing into the next generation.
The annual western bean cutworm flight continues to increase across select regions of the corn-growing region. The greatest pressure at the present time appears to be in the northern half of Indiana where moth counts are the highest and where reports of egg laying and masses are more common. As a result, High western bean cutworm risks are now in place as peak flight moves through the northern portions of Indiana. Additional areas of concern remain in northern Kansas and Nebraska as well as sandier soils in western Iowa where a Moderate risk is in place. Additional Moderate risk regions are found in Wisconsin where the moth population continues to increase in a scattered fashion, and eastern Illinois is also likely seeing some moth activity. Growers from northwest into northeast Ohio should continue to monitor moth activity and signs of egg laying in the next week as well as into extreme southwest and southern Michigan where Moderate risks are in place. Low risks envelop much of the remainder of the corn-growing region where moth captures are lower or not present. Problems with this particular insect are likely to be more isolated to scattered but locally intense this year, so if you are especially in a Moderate or High risk region, consider monitoring your fields for western bean cutworm moths as well as egg masses and take appropriate action where it is needed.
Corn rootworm hatch and beetle activity continues across much of the corn-growing region. Remaining corn rootworm hatches are likely focused along and north of I-94 in North Dakota, central and northern Minnesota, and northern Wisconsin while corn rootworm beetle activity is likely further south. Several reports of beetle emergence and counts have been observed all across the corn-growing region in the last few weeks. Growers should continue to monitor their fields and take note of beetle populations. High beetle populations would suggest the potential need to adjust decisions for next growing season. To assess root conditions and larvae populations, it is suggested that growers not only pull up field corn but also volunteer corn in soybean fields, taking note whether the field or volunteer corn is GMO or non-GMO. If the plant pulls up easily, assess the roots for signs of corn rootworm feeding and/or larvae. If the roots look hairy and largely undisturbed, then you many not have a problem but if there are few hairs and signs of feeding, as well as the presence of larvae, keep a close eye on the area and consider making changes to your growing plan in 2015.
Soybean aphid populations continue to remain low across virtually the entire upper Midwest and Great Lakes region, but there has been an increase in both coverage and populations in several areas due to recent favorable weather conditions for soybean aphid regeneration. Given low populations present, the soybean aphid risk level throughout the next week is kept in the Low category. Winged soybean aphids are becoming more prevalent especially in western portions of the upper Midwest which may lead to a potential migration event late in the weekend and early next week when an unseasonably strong area of low pressure develops over the Great Lakes region and northwest winds lock in across much of the upper Midwest and western Great Lakes. Along with these northwest winds, a return to a potentially more favorable weather pattern for continued soybean aphid population increases is predicted by the weekend and into much of next week across the upper Midwest. With many soybean fields in full bloom now and at critical growth stages where economic impacts are possible, growers are urged to actively scout fields and take note of population dynamics in between scouting periods. If you see a rapid increase in aphid populations, scout more often and be prepared to make decisions whether to treat or not based on provided economic thresholds, crop stage, and what is going on in the field and not necessarily what the regional report is saying.