Seed destruction of weeds in southern US crops using heat and narrow-windrow burning

Abstract

Narrow-windrow burning has been a successful form of harvest weed seed control in Australian cropping systems, but little is known about the efficacy of narrow-windrow burning on weed seeds infesting U.S. cropping systems. An experiment was conducted using a high-fire kiln that exposed various grass and broadleaf weed seeds to temperatures of 200, 300, 400, 500, and 600 C for 20, 40, 60, and 80 s to determine the temperature and time needed to kill weed seeds. Weeds evaluated included Italian ryegrass, barnyardgrass, johnsongrass, sicklepod, Palmer amaranth, prickly sida, velvetleaf, pitted morningglory, and hemp sesbania. Two field experiments were also conducted over consecutive growing seasons, with the first experiment aimed at determining the amount of heat produced during burning of narrow windrows of soybean harvest residues (chaff and straw) and the effect of this heat on weed seed mortality. The second field experiment aimed to determine the effect of wind speed on the duration and intensity of burning narrow windrows of soybean harvest residues. Following exposure to the highest temperature and longest duration in the kiln, only sicklepod showed any survival (<1% average); however, in most cases, the seeds were completely destroyed (ash). A heat index of only 22,600 was needed to kill all seeds of Palmer amaranth, barnyardgrass, and Italian ryegrass. In the field, all seeds of the evaluated weed species were completely destroyed by narrow-windrow burning of 1.08 to 1.95 kg m−2 of soybean residues. The burn duration of the soybean harvest residues declined as wind speed increased. Findings from the kiln and field experiments show that complete kill is likely for weed seeds concentrated into narrow windrows of burned soybean residues. Given the low cost of implementation of narrow-windrow burning and the seed kill efficacy on various weed species, this strategy may be an attractive option for destroying weed seed.

Amaranthus retroflexus L. (Redroot Pigweed): Effects of Elevated CO2 and Soil Moisture on Growth and Biomass and the Effect of Radiant Heat on Seed Germination

“…Seed size is one possible factor in this result, since in two other small-seeded species, Nicotiana glauca [45] and Dinebra panicea [46], exposure to temperatures of 100 • C and above for a short time (180 s) significantly reduced germination. The finding in this study that the time of exposure required to reduce seed viability is reduced according to increase in temperature aligns with previous research [20]. Therefore, we recommend fire, possibly in the form of stubble burning, be further investigated for use in the control of this weed in cropping situations.…”

“…Additionally, heat treatment of seeds prior to germination was investigated to predict the effects of fire on the soil seed bank. Stubble burning is an established control method for other weed species [20], and it may become necessary as an alternate to herbicide application for this species [15][16][17]. This work aims to derive a more thorough understanding of how anthropogenic climate change affects the biology and ecology of this important agricultural weed, through a closer investigation of some principles of its basic biology, since the combined effects of elevated atmospheric carbon dioxide and drought on this species are yet to be fully understood.…”

Genetic diversity and population structure of a global invader Mayweed chamomile (Anthemis cotula): management implications

“…Due to human-mediated movement of A. cotula , improved sanitary practices will be important for limiting the spread of herbicide resistance genes and other problematic genotypes. Established measures include limiting machinery movement, improving cleaning of equipment, ensuring use of certified seed and using new technology to clean grain of seeds during harvest ( Gervilla et al 2019 ; Norsworthy et al 2020 ; Owen and Powles 2020 ). Trade and transportation of seed contamination of crops, especially with herbicide-resistant weeds, within and between continents ( Shimono et al 2010 , 2020 ) can be particularly problematic.…”

Effects of Narrow-Windrow Burning on Weed Dynamics in Soybean in Louisiana

“…In Arkansas, NWB was evaluated on nine common weed species in soybean residue. All seeds evaluated were completely destroyed in varying levels of soybean residue (1.08-1.95 kg m −2 ), which effectively is decreasing returns to the soil seedbank (Norsworthy et al, 2020). This additional IWM tactic serves to prolong other effective IWM tactics, such as the use of herbicides which is steadily decreasing, due to the increasing problem of HR weeds.…”