5 MIN READ

Benefit for planting SmartStax® PRO with RNAi Technology*

December 14, 2021

Increasing pressure from the western corn rootworm (WCRW) and northern corn rootworm (NCRW) across the Corn Belt is making management of this problematic pest increasingly difficult. SmartStax® PRO with RNAi Technology is the next generation of corn rootworm (CRW) protection.

Corn rootworm larvae feeding on corn roots can cause considerable physical damage to a corn crop which can potentially result in severe economic loss. For every node of roots pruned by CRW larvae, farmers can expect up to a 15% yield loss on average.1 Damaged roots impact a plant’s nutrient and water uptake ability and can potentially increase the risk of root lodging, making harvest challenging and time-consuming (Figures 1 and 2).

Built on the strong foundation of SmartStax® Technology, SmartStax® PRO with RNAi Technology introduces a new RNAi-based mode of action, making it the first product on the market with three modes of action for CRW control. SmartStax® Technology contains two modes of action for CRW control based on Bacillus thuringiensis (Bt) proteins (Cry34Ab1/Cry35Ab1 and Cry3Bb1). SmartStax® PRO with RNAi Technology builds on that proven SmartStax® Technology by using those same proteins and adding a new mode of action through RNAi (RNA interference) technology. This novel mode of action, when combined with the two existing B.t. modes of action, can help increase a farmer’s ability to control CRW while also helping to maintain trait durability.

Bayer is the first to develop RNAi Technology to combat CRW, which offers a new, third mode of action against the pest. By interfering with a corn rootworm’s ability to create a specific protein critical to its own survival, RNAi Technology effectively causes mortality after ingestion (Figure 1).

*SmartStax® PRO corn products will be commercially available for the 2022 growing season.

Figure 1. SmartStax® PRO with RNAi Technology protected corn roots at Davenport, Iowa on July 1, 2021.
Figure 1. SmartStax® PRO with RNAi Technology protected corn roots at Davenport, Iowa on July 1, 2021.

Bayer internal trials have shown that SmartStax® PRO with RNAi Technology provides better control of CRW than many leading competitive traits (Figures 2, 3, and 4). While this new technology provides improved control of CRW, proper management is still needed to help ensure the durability of this new trait. Growers should continue to employ best management practices such as crop rotation, use of soil insecticides with non-CRW traited products, etc. to manage CRW populations. Long-term corn on corn rotations with severe CRW pressure should be rotated to soybean to break the CRW life cycle.

Figure 2. Comparison of SmartStax® PRO with RNAi Technology corn rootworm protected product compared to Qrome® Products with corn rootworm protection.
Figure 2. Comparison of SmartStax® PRO with RNAi Technology corn rootworm protected product compared to Qrome® Products with corn rootworm protection.

*SmartStax® PRO corn products will be commercially available for the 2022 growing season.


Figure 3. Comparison of corn plant roots protected with SmartStax® PRO with RNAi Technology and QROME® technology at Davenport, Iowa on July 1, 2021.

Figure 4. Overview of root lodging at a Lansing, Iowa plot with different corn rootworm protected products on August 3, 2021.
Figure 4. Overview of root lodging at a Lansing, Iowa plot with different corn rootworm protected products on August 3, 2021.

*SmartStax® PRO corn products will be commercially available for the 2022 growing season.


Matthew Nelson

Technical Agronomist

Sources:

1 Tinsley, N.A., Estes, R.E., and Gray, M.E. 2012. Validation of a nested error component model to estimate damage caused by corn rootworm larvae. Journal of Applied Entomology. DOI:10.1111/j.1439-0418.2012.01776.x.

Hodgson, E. and Gassmann, A.J. 2015. Corn rootworm management update. Integrated Crop Management. Iowa State University.

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