Jennifer Dudak¹, Reagan Noland², Tom Isakeit¹, Terry Wheeler³, Benjamin McKnight¹, and Gaylon Morgan⁵

1. Texas A&M AgriLife Extension Service, College Station, TX
2. Texas A&M AgriLife Extension Service, San Angelo, TX
3. Texas A&M AgriLife Research, Lubbock, TX
4. Cotton Incorporated, Cary, NC

Reniform nematodes have proven to be detrimental to U.S. cotton production. In 2019, an estimated 189,000 bales of cotton were lost due to this pest hindering cotton performance (Figure 1) (Lawrence et al., 2020; United States Department of Agriculture National Statistics Service, 2020).

TRCN 2021 Figures-1

A team of Texas A&M AgriLife scientists initiated a statewide cultivar testing effort in 2019 to evaluate efficacy of both new and previously available genetic resistance in reniform-infested fields. Cotton cultivars tested include a range of both root-knot and reniform nematode resistance, as well as a nematode-susceptible check (Table 1). Each cultivar was planted with, and without an in-furrow nematicide, fluopyram and prothioconazole (Propulse) at 13.6 oz/acre.

The continuation of this project in 2020 affirmed the increased yield potential of cotton with specific reniform nematode resistance in reniform nematode infested fields. In 2019, PHY 443 W3FE yielded among the top at all locations compared to other root-knot resistant cultivars and susceptible check (Figure 2). This increase was between 34-48% depending on location. The application of Propulse did not impact yields at any of the three locations in 2019. The addition of two more reniform resistant cultivars (PHY 332 W3FE and DP 2143NR B3XF) and one more location (Lubbock, TX), produced similar results in 2020. All three of the reniform resistant cultivars were among the top yielding at all locations. However, PHY 443 W3FE and PHY 332 W3FE yielded higher than DP 2143NR B3XF, depending on location (Figure 3). The application of nematicide decreased yields by 5% compared to no treatment across the Damon, College Station, and Lubbock sites combined, but did not impact yields in Wall. Across a combined seven site-years of this project the reniform resistant cultivars demonstrated potential for a 45% yield increase compared to the non-reniform resistant cultivars included in this study.

TRCN 2021 Figures-2

TRCN 2021 Figures-3

Key findings from this research are 1) increased yield potential with reniform resistant cultivars, and 2) the lack of a yield benefit from root-knot nematode resistant cultivars in reniform fields. Genetic resistance is species-specific between these two nematodes in cotton, so knowledge of which species are present is critical to inform cultivar selection. All three of the reniform resistant cultivars evaluated in this research were commercialized in 2021, and prices are comparable to some of the most common non-reniform resistant cultivars grown throughout the state of Texas (Plains Cotton Growers Seed Cost Calculator).

TRCN 2021 Figures-4

If you suspect a reniform nematode infestation in your field, soil samples can be analyzed for nematodes at the Texas Plant Disease Diagnostic Lab in College Station (https://plantclinic.tamu.edu/).

Citations

Lawrence, K., A. Hagan, R. Norton, J. Hu, T. Faske, et al. 2020. Cotton Disease Loss Estimate Committee Report, 2019. Proc. Beltwide Cott. Conf.: 117–119.

United States Department of Agriculture National Statistics Service. 2020. Crop Production 2019 Summary