Cotton stalk management and a cover crop produce minimal effects on cotton leafroll dwarf virus

Authors: FRAZIER, SAMUEL - Auburn University; BROWN, STEVEN - Auburn University; Read, Quentin; JACOBSON, ALANA - Auburn University; CONNER, KASSIE - Auburn University; ESCALANTE, CESAR - Auburn University; Balkcom, Kipling

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2024
Publication Date: 12/30/2024
Citation: Frazier, S., Brown, S.M., Read, Q.D., Jacobson, A.L., Conner, K., Escalante, C., Balkcom, K.S. 2024. Cotton stalk management and a cover crop produce minimal effects on cotton leafroll dwarf virus. Agronomy Journal. 117(1):e70002. https://doi.org/10.1002/agj2.70002.
DOI: https://doi.org/10.1002/agj2.70002

Interpretive Summary: Cotton leafroll dwarf virus (CLRDV), a new virus affecting cotton was first reported in the United States in 2017. The previous year’s cotton stalks are one CLRDV inoculum source, so stalk destruction methods (SDMs) could be an effective CLRDV management tool. However, SDMs that disturb the soil surface can decrease soil health for southeastern soils, but a cover crop could offset aggressive SDMs. Therefore, ARS scientists in Auburn, AL and Raleigh, NC with Auburn Univ. collaborators examined three SDMs (Destroy, Pull, Mow) across two cover crops (fallow and rye/clover mix) and two cotton varieties (‘DP 2055 B3XF’ and ‘PHY 400 W3FE’) to determine how selected cotton parameters, soil strength, and two CLRDV incidence sample times (pre-harvest and post-harvest) were affected during the 2021 and 2022 growing seasons at three locations. No SDMs affected any factors, except soil strength and cotton yield. The Pull and Mow SDMs both increased soil strength compared to the Destroy SDM. An 8% yield increase (Pull > Mow) was observed, but the Destroy SDM yield did not differ from Pull or Mow SDMs. Verifying that aggressive SDMs were unnecessary to reduce CLRDV incidence helps to preserve soil health benefits, but this result suggests other CLRDV reservoirs exist that may contribute to in-season CLRDV infections. Efforts to identify cultural practices that reduce CLRDV incidence rates should continue, in addition to cotton breeding efforts to identify CLRDV resistance.

Technical Abstract: Cotton leafroll dwarf virus (CLRDV), a new virus affecting cotton (Gossypium hirsutum L.), was first reported in the United States in 2017. One CLRDV inoculum source includes the previous year’s cotton stalks, so stalk destruction methods (SDMs) could be an effective CLRDV management tool. However, tillage intensive SDMs can be detrimental for southeastern soils, but a cover crop could offset aggressive SDMs. Therefore, we examined three SDMs (Destroy, Pull, Mow) across two cover crops [fallow and rye (Secale cereale L.) /clover (Trifolium incarnatum L.) mix] and two cotton varieties (‘DP 2055 B3XF’ and ‘PHY 400 W3FE’) to determine how selected cotton parameters, penetration resistance (PR), and two CLRDV incidence sample times (pre-harvest and post-harvest) were affected across six environments during the 2021 and 2022 growing seasons. None of the SDMs affected any factors examined in this experiment, except PR and cotton yield. The Pull and Mow SDMs both increased PR compared to the Destroy SDM. An 8% yield increase (Pull > Mow) was observed, but the Destroy SDM yield did not differ from Pull or Mow SDMs. The rye/clover mix also increased PR. Although cotton stands were 14.8% greater with no cover crop, subsequent cotton yield and fiber quality were minimally affected by cover crops. The rye/clover mix increased post-harvest CLRDV incidence, but the increase was not agronomically significant compared to fallow. Post-harvest CLRDV incidence rates were 209% greater than pre-harvest. Continuing to identify and evaluate cultural practices that reduce CLRDV incidence is imperative to prevent negative impacts.