This year Nebraska Extension in Nemaha County will be in its sixth year in southeast Nebraska with a pheromone trapping network to monitor black cutworm, variegated cutworm and true armyworm moths in southeast Nebraska. This is a local network of traps in southeast Nebraska during the 2021 planting season. Traps have been placed into service March 28th – April 1st in southeast Nebraska.
Gary Lesoing, Extension Educator in Nemaha County has recruited people in Nemaha, Richardson, Otoe, Lancaster and Pawnee Counties to monitor the pheromone traps. We have 2 sites for traps in Nemaha County; at the courthouse in Auburn and in Johnson. Last week we also added a monitoring site near Pawnee City in Pawnee County. This is a new site for this year. There is a specific trap and pheromone lure for each kind of moth.
Black cutworms and true armyworms migrate from southern states each year. Many times they blow in when storms come up from the south. Variegated cutworms overwinter in Nebraska. They are generally climbers and feed on leaves. Many times they are a problem in garden crops, even asparagus. When there are very high numbers, they can defoliate crops, such as soybeans and alfalfa. The variegated cutworm is not a pest every year, but with high infestations may require treatment with a pesticide. Sometimes alfalfa that has been harvested does not grow back due to feeding by variegated cutworms on the foliage. Under these circumstances it may require treatment. Infestations of the variegated cutworm are very sporadic.
True armyworms are usually a pest of pasture grasses or cereal crops, such as wheat or cereal cover crops like barley or rye. They could become a pest in seedling corn if at high numbers in a cover crop and corn is planted into it.
Black cutworms can be a potential pest in corn and even sometimes soybeans. Monitoring of the black cutworm moths has been conducted for several years in Missouri. There is a model that has been developed to determine when farmers can expect the first cutting by black cutworm larvae, depending upon growing degree-days following the first intense capture of the black cutworm moth. The first intense capture is when 8 or more moths are captured over a consecutive two night period. This is the biofix, the date when to start counting growing degree-days. The black cutworm larvae are large enough to cut plants when 300 growing degree-days have accumulated. To date there has not been a significant black cutworm moth capture in our network this spring. It is important to scout fields before the 300 growing degree-days accumulation though. In 2017 armyworms caused problems in some areas of Nebraska, so it was decided to monitor them as well since then. Nebraska Extension in Nemaha county will be summarizing moth trap count numbers and will try to keep crop advisors and farmers abreast of potential pest problems later this spring. Check the link below to view the data being collected. This data collected will provide information to help determine when and if there may be a problem with these types of cutworms or armyworms in Nebraska in 2021. We are also planning to monitor for the brown marmorated stink bug this summer. It is an invasive pest in a number of crops, especially in states to the east of us. It has been found in some locations in southeast Nebraska, but not at levels to cause concern. If you have questions about this program you can contact me at the Nemaha County Extension office at (402) 274-4755, (402) 274-9639 (cell) or email@example.com .