Aphid-resistant soybean varieties for Minnesota
Soybean aphid is an invasive pest of soybean that continues to reach economically damaging levels in Minnesota. Foliar insecticides are commonly applied when aphid densities reach 250 aphids per plant to prevent economic loss. Yield loss and control costs can be significant for Minnesota soybean growers.
Photo: A. Hanson, University of Minnesota
Figure 1. Resistance genes can effectively suppress soybean aphid: Aphid-susceptible (left) and resistant (right) soybean lines.
Using aphid-resistant soybean varieties holds promise as a more sustainable approach to soybean aphid management. Soybean varieties that possess resistance genes, called Rag genes (Rag1, Rag2, etc.), affect colonization and population growth of soybean aphid (Figure 1).
Figure 2. Rag1 and Rag2 resistance genes do not cause yield drag. Yield of soybean varieties IA2104 (aphid-susceptible) and IA104RA12(Rag1 + Rag2 pyramid) with low aphid pressure (<20 average aphids per plant at most during the growing season), Rosemount, MN, 2016.
Soybean varieties with Rag1 or Rag2 genes have significantly suppressed aphid numbers and protected yields in multiple states and years; varieties with multiple (i.e., pyramided) Rag genes can provide further protection (McCarville et al., 2014). Independent university research has shown that varieties can have Rag1 and Rag2 genes without yield reduction (e.g., Figure 2) when compared to similar aphid-susceptible soybean lines not under aphid pressure (Brace & Fehr, 2012).
Resistant varieties offer season-long protection from aphids. In contrast, insecticidal seed treatments (neonicotinoids) only provide temporary protection up to about 40 days after planting (McCarville & O’Neal, 2013), which is typically before aphid populations are established. The likelihood of needing to apply foliar insecticides for soybean aphid is also reduced by using resistant varieties.
Availability and use of aphid-resistant soybean
Commercial varieties containing Rag genes have been available since 2009, but have been uncommon among early-maturity soybean varieties developed for Minnesota. Search of seed catalogs identified several soybean varieties with aphid-resistance (Rag) genes in early maturity groups and with other traits potentially suitable for Minnesota soybean growers (Table 1). Please inform us of any additional varieties with resistance that may have been missed in our search.
Table 1. Soybean varieties carrying Rag genes available in Minnesota as of November, 2016.
|Other advertised characteristics1|
|Resistance gene(s)||Herbicide resistance trait||PRR||SCN||IDC||SDS||BSR||Org.|
|0543||Gold Country Seed||0.5||Rag1||RR 2Y3||S4||R||–||–||–||N|
|LS 10R551N||Legend Seeds||1.0||Rag1||RR 2Y||R||R||–||–||–||N|
|NS1040NR2||NorthStar Genetics||1.1||Rag1||RR 2Y||R||R||–||–||–||N|
|3511 R2YN||Thunder Seed||1.1||Rag1||RR 2Y||R||R||T||–||–||N|
|Viking 0.1544AT||Viking Seeds||1.5||Rag1||None||–||S||T||–||–||Y|
|Viking 2188NAT||2.1||Rag1 & Rag2||None||–||R||–||–||–||N|
|Viking 0.2188AT12N||2.1||Rag1 & Rag2||None||–||R||–||–||–||Y|
|Viking 0.1IA2104RA12||2.3||Rag1 & Rag2||None||–||–||–||R||–||Y|
|Viking 0.2399AT12N||2.4||Rag1 & Rag2||None||–||R||–||–||–||Y|
|1PRR: Phytopthora root rot; SCN: Soybean cyst nematode; IDC: Iron deficiency chlorosis; SDS: Sudden death syndrome; BSR: Brown stem rot; Org: Organic seed
2RM: Relative maturity
3RR 2Y: Genuity Roundup Ready 2 Yield
4R: Resistant; T: Tolerant; S: Susceptible; Y: yes; N: no
Continue to scout for aphids
Scouting aphid-resistant varieties should still occur as aphids can occasionally reach damaging levels on resistant plants. Soybean aphid populations (biotypes) that can overcome aphid-resistance genes do exist, but their occurrence varies throughout the region and over time (Cooper et al. 2015). Even though soybean varieties with single resistance genes, such as Rag1 alone, have been effective at suppressing soybean aphid in Minnesota (Hanson et al., 2016), varieties with pyramided resistance genes, such as Rag1+Rag2, offer more robust protection from resistance-breaking aphid biotypes (McCarville et al. 2014).
Planting well-adapted aphid-resistant varieties could improve the sustainability of soybean production. It is our hope that this list, which will be updated over time, will allow growers to more easily find aphid-resistant seed.
- Brace, R.C., and W.H. Fehr. 2012. Impact of combining the Rag1 and Rag2 alleles for aphid resistance on agronomic and seed traits of soybean. Crop Sci. 52:2070–2074
- Cooper, et al. 2015. Geographic distribution of soybean aphid biotypes in the United States and Canada during 2008-2010. Crop Sci. 55:2598-2608.
- Hanson et al. 2016. Sources of soybean aphid resistance in early-maturing soybean germplasm. Crop Sci. 56:154-163.
- McCarville, M.T., and M.E. O’Neal. 2013. Soybean aphid (Aphididae: Hemiptera) population growth as affected by host plant resistance and an insecticidal seed treatment. Journal of Economic Entomology: 106:1302-1309.
- McCarville, M.T. et al. 2014. One gene versus two: A regional study on the efficacy of single gene versus pyramided resistance for soybean aphid management. Journal of Economic Entomology 107:1680-1687