2024 Soybean Gall Midge Alerts (Scroll Down to See Previous Alerts)
June 6th, 2024 Alert: Adults Emerge in Minnesota, White Larvae in East-Central Nebraska
Adult Emergence in Minnesota
Emergence of soybean gall midge adults is now underway in Minnesota (Fig. 1). On June 4, one adult soybean gall midge was collected in a trap deployed in a field in southwest Minnesota. Most soybean fields in the area are not yet at the V2 growth stage, so are not susceptible to this pest. This is the earliest detection of soybean gall midge in Minnesota since monitoring began in 2019.
Fig. 1. Adult Emergence as of 6/5/2024
East-Central Nebraska
Emergence has now occurred at all sites in east-central Nebraska except for one of the three sites at the Eastern Nebraska Research and Extension Center. On June 5th, white larvae (Fig. 2) were found on early-planted soybean (April 9th) at ENREEC.
No emergence has been reported in northeast Nebraska, Iowa, or South Dakota.
Fig 2. White larvae in Saunders County, NE on 6/5/2024.
May 31st, 2024 Alert: Soybean Gall Midge Emergence Detected in Nebraska
On May 30th, soybean gall midge adult emergence was observed in east-central Nebraska in Saunders and Lancaster Counties (Fig. 1). Soybean stage is a critical factor for the susceptibility of soybean to soybean gall midge. Only soybean with fissures at the base of the plant are susceptible to soybean gall midge infestation (Fig. 2). Soybean planted in late April and early May are mostly at the V2 stage; however, those planted in mid to late May are VE-V1. Research being conducted this season shows that soybean planted on the same day at different depths can impact the soybean stage of development.
Soybean Gall Midge: Should I Spray Checklist
❏ Soybean gall midge adults have emerged in my area
❏ My soybean field is at the V2 stage or greater (Fig. 2)
❏ I observed soybean gall midge injury in the adjacent field last year
Figure 1. Soybean gall midge alert network trap sites with a yellow dot indicating activity and the number of adults collected at that site.
Figure 2. Soybean plants (a) at V1 and V2 stage with close up of the stem (b) showing differences in the formation of fissures or cracks at the V2 stage.
Management
Management of soybean gall midge has been difficult. Foliar sprays have shown some response but are inconsistent between locations and years. No specific foliar-applied product tested to date has provided consistent control of SGM. Research to date suggests that growers can consider using a combination product that contains a pyrethroid. If an application is being considered, it should only be made in soybean fields where a history of issues with soybean gall midge injury has occurred. Since soybean gall midge is a field edge-infesting pest, growers may only need to treat the first 60 to 120 feet of a field edge that is directly adjacent to a field that was injured the previous year. Do not treat any soybean fields prior to V2, as they are not susceptible to infestation due to the lack of fissures or cracks at the base of the stem.
Hilling or covering the base of soybean stems with soil has also been found to be a very effective strategy with almost complete control of soybean gall midge. This is a difficult practice to implement when soybean plants are small, as they can easily be completely covered by soil. Studies are being conducted to evaluate the timing of hilling relative to the plant development stage. More information on hilling is available through the soybeangallmidge.org website. Little is known about the impact this management strategy could have on soybean gall midge movement in a field. Although no field studies have been conducted, it is possible that adults may continue to move into the field until they find a susceptible plant.
With no detection of soybean gall midge in other parts of the network, it would be advisable to wait for emergence to occur in those areas. You can continue to follow adult emergence at all locations through soybeangallmidge.org.