Influence of burning post-harvest sugarcane residue density and moisture content on surface deposited divine nightshade and itchgrass emergence

Authors: Spaunhorst, Douglas; ORGERON, ALBERT - LSU Agcenter; White, Paul

Submitted to: American Society of Sugar Cane Technologists
Publication Type: Abstract Only
Publication Acceptance Date: 4/30/2019
Publication Date: 6/1/2019
Citation: Spaunhorst, D.J., Orgeron, A.J., White Jr, P.M. 2019. Influence of burning post-harvest sugarcane residue density and moisture content on surface deposited divine nightshade and itchgrass emergence [abstract]. Journal American Society of Sugarcane Technologists. 39:29-30.

Interpretive Summary:

Technical Abstract: Burning is a standard practice to remove post-harvest sugarcane (Saccharum spp. hybrids) residue before spring regrowth and the post-harvest residue condition can range from dry to damp. Live-fires were simulated from field-collected post-harvest sugarcane residue and seeds of divine nightshade (Solanum nigrescens) and itchgrass [Rottboellia cochinchinensis (Lour.) Clayton] were exposed to dry and moistened post-harvest sugarcane residue at four densities (6.1 to 24.2 Mg ha-1) and a nonburned control. Burning post-harvest residue with 44% moisture when wind speeds were lower allowed the fire to smolder, which reduced weed emergence by 23% compared to burning post-harvest residue with 30% moisture during breezy conditions. The moistened 6.1 Mg ha-1 post-harvest residue treatment resulted in 53% more divine nightshade and itchgrass emergence when compared to dry 6.1 Mg ha-1 post-harvest residue after burning, and greater emergence was reflected by more divine nightshade seed survival than itchgrass. The burn duration was not influenced by dry or moistened post-harvest residue; however, the burn duration increased 103 and 56% as the amount of post-harvest residue increased from 6.1 to 12.1 Mg ha-1 and 12.1 to 18.2 Mg ha-1, respectively. The combination of high wind speeds plus moistened post-harvest residue did not increase the maximum burn temperature near the soil surface, but surface deposited divine nightshade and itchgrass seed were susceptible to 100 C for 154 s or more. The fluid-filled and fleshy content that comprises divine nightshade fruit protected seed from short durations of high temperatures, but may not insulate seed long enough during extended exposure to a smoldering fire. This research demonstrates that burning post-harvest residue from fields with poor stands or older ratoon, especially when post-harvest residue is abundantly wet or when water ponds in the wheel furrow, will not produce temperatures lethal to divine nightshade and itchgrass seed.