Since 2011, Extension entomologists in Alabama have participated in the Soybean Insect Losses Report published annually in the Midsouth Entomologist. These estimates are based on the observations of Extension entomologists and informal surveys of other Extension personnel, growers, crop consultants and industry professionals that are involved in soybean production in Alabama. Estimates are meant to encompass the entire state, so they may not exactly reflect the soybean insect situation at a specific location or individual farm.
According to the USDA-FSA, Alabama growers planted 266,818 acres of soybeans in 2020. The majority of the state’s acres were planted in the Tennessee Valley (=65.5%). On average, growers made 1.44 insecticide applications per acre, costing $7.92 per application. The total cost of insect control in 2020 (foliar application cost + seed treatment cost + scouting fees) was $17.85 per acre. When accounting for yield losses to insects ($27.85/A) and total cost of controls, 2020 soybean insect management cost Alabama growers $45.70 per acre ($12M statewide).
The stink bug complex was the dominate pest in 2020. Nearly 75% of the acres were treated an average of 1.25 times for stink bugs. The southern green stink bug was the dominate species statewide (=60% of complex), followed by the brown stink bug (=20%), redbanded stink bug (=10%), green stink bug (=5%) and brown marmorated stink bug (=5%).
Although not distributed everywhere, the redbanded stink bug was a major factor in the Blackbelt and Gulf Coast regions. In some instances, growers made up to 3 applications to control this pest. Velvetbean caterpillars (=35%) and soybean loopers (=8%) also required treatments statewide. The velvetbean caterpillar is normally a pest of south Alabama, however in 2020 it migrated north, requiring treatment in the Sand Mountain region. Other pests that required treatments were kudzu bugs (=5%) and green cloverworms (=2%).
Overall, insects were not a major yield limiting factor this season. When looking forward to 2021, growers in the Black Belt and Gulf Coast should consider budgeting an extra insecticide application or two for redbanded stink bugs (RBSB). With the projected La Nina winter bringing warm, dry conditions to the south, this pest is likely to survive the winter in Alabama. This spring, we found adults as far north as Prattville in early April.
The RBSB was readily established in the I-20 Corridor in the western part of the state during the growing season. If they overwinter around I-20 this year, we may have the potential to find some in the TN Valley late in the season next year. Dr. Tyler Towles from LSU gave a presentation on RBSB for the 2020 Alabama Row Crop Short Course. You can find that video here.