Weed Control and Peanut Tolerance with Ethalfluralin-Based Herbicide Systems

Field studies were conducted from 2007 through 2009 to determine weed efficacy and peanut (Arachis hypogaea L.) response to herbicide systems that included ethalfluralin applied preplant incorporated. Control of devil's claw (Proboscidea louisianica (Mill.) Thellung), yellow nutsedge (Cyperus esculentus L.), Palmer amaranth (Amaranthus palmeri S. Wats.), and puncturevine (Tribulus terrestris L.) was most consistent with ethalfluralin followed by either imazapic or imazethapyr applied postemergence. Peanut stunting was 19% when paraquat alone was applied early-postemergence. Stunting increased to greater than 30% when ethalfluralin applied preplant incorporated was followed by S-metolachlor applied preemergence and paraquat applied early-postemergence. Stunting (7%) was also observed when ethalfluralin was followed by flumioxazin plus S-metolachlor applied preemergence with lactofen applied mid-postemergence. Ethalfluralin followed by paraquat applied early-postemergence reduced peanut yield when compared to the nontreated check. Ethalfluralin applied preplant incorporated followed by imazapic applied mid-postemergence provided the greatest yield (6220 kg/ha). None of the herbicide treatments reduced peanut grade (sound mature kernels plus sound splits) when compared with the nontreated check

Sesame ( Sesamum indicum

Studies were conducted during the 2007 and 2008 growing seasons under weed-free conditions in South Texas and the High Plains region of Texas to evaluate preemergence herbicides for sesame tolerance. No reduction in sesame stand was noted with any herbicide at south Texas location; however, at the High Plains location, linuron at the 2X rate reduced stand counts 28 days after treatment (DAT) in 2007 and diuron reduced sesame stand 147 DAT in 2008 when compared with the untreated check. At the 1/2X rate all herbicides exhibited minimal stunting while at the 1X rate stunting was variable and varied between locations. At the 2X rate, all herbicides caused sesame stunting compared to the untreated check. No herbicide, with the exception of linuron at the 2X rate in 2008 at the High Plains location, reduced sesame yield when compared with the untreated check. Although some herbicide treatments resulted in sesame stunting, this did not result in any yield reductions and this can be attributed to the ability of the sesame plant to compensate for injury and/or reduced stands

Peanut Cultivar Response to Flumioxazin Applied Preemergence and Imazapic Applied Postemergence

Field studies were conducted during 2009 and 2010 in Texas at Yoakum and Lamesa to determine peanut cultivar response to flumioxazin applied preemergence (0.053, 0.107, and 0.214 kg ai ha−1) and imazapic applied postemergence (0.035, 0.071, and 0.141 kg ai ha−1). At Yoakum, two cultivars (Tamrun OL01, Tamrun OL07) were evaluated while at Lamesa, four cultivars (FlavorRunner 458, Tamrun OL01, Tamrun OL02, and Tamrun OL07) were evaluated. In 2009, no stunting was noted at Yoakum with any herbicide regardless of cultivar. At Lamesa, FlavorRunner 458 and Tamrun OL01 were stunted at least 6% with the 0.21 kg ha−1 rate of flumioxazin and 6 to 17% with the 0.07 and 0.14 kg ha−1 rate of imazapic. Tamrun OL02 was stunted by all rates of flumioxazin (5%) and imazapic (5 to 18%) while Tamrun OL07 was stunted by all rates of flumioxazin (6 to 12%) and imazapic (7 to 15%) with the exception of flumioxazin at 0.05 kg ha−1. Flumioxazin did not have an effect on yield while all imazapic rates reduced yields when compared with the non-treated control. In 2010 at Yoakum, little (<2%) or no herbicide stunting was noted on any cultivar and only imazapic at 0.14 kg ha−1 caused significant stunting (7%). No yield differences were noted between herbicides regardless of cultivar. At Lamesa, all cultivars were affected (6 to 9% stunting) by herbicide treatments. No peanut stunting was noted with flumioxazin at 0.05 kg ha−1 while imazapic at 0.04 kg ha−1 and flumioxazin at 0.11 kg ha−1 resulted in 4 and 6% stunting, respectively. Flumioxazin at 0.21 kg ha−1 and imazapic at 0.07 kg ha−1 resulted in 12% stunting and imazapic at 0.14 kg ha−1 stunted peanut 19%. Both Tamrun OL01 and Tamrun OL07 produced lower yields (≤6369 kg ha−1) than FlavorRunner 458 (7252 kg ha−1). Tamrun OL02 yields were intermediate (6889 kg ha−1). Peanut yields from herbicide treatments were not different from the non-treated control

Sesame (Sesamum indicum L.) Growth and Yield as Influenced by Preemergence Herbicides

Studies were conducted during the 2007 and 2008 growing seasons under weed-free conditions in South Texas and the High Plains region of Texas to evaluate preemergence herbicides for sesame tolerance. No reduction in sesame stand was noted with any herbicide at south Texas location; however, at the High Plains location, linuron at the 2X rate reduced stand counts 28 days after treatment (DAT) in 2007 and diuron reduced sesame stand 147 DAT in 2008 when compared with the untreated check. At the 1/2X rate all herbicides exhibited minimal stunting while at the 1X rate stunting was variable and varied between locations. At the 2X rate, all herbicides caused sesame stunting compared to the untreated check. No herbicide, with the exception of linuron at the 2X rate in 2008 at the High Plains location, reduced sesame yield when compared with the untreated check. Although some herbicide treatments resulted in sesame stunting, this did not result in any yield reductions and this can be attributed to the ability of the sesame plant to compensate for injury and/or reduced stands

Peanut Cultivar Response to Flumioxazin Applied Preemergence and Imazapic Applied Postemergence

Field studies were conducted during 2009 and 2010 in Texas at Yoakum and Lamesa to determine peanut cultivar response to flumioxazin applied preemergence (0.053, 0.107, and 0.214 kg ai ha −1 ) and imazapic applied postemergence (0.035, 0.071, and 0.141 kg ai ha −1 ). At Yoakum, two cultivars (Tamrun OL01, Tamrun OL07) were evaluated while at Lamesa, four cultivars (FlavorRunner 458, Tamrun OL01, Tamrun OL02, and Tamrun OL07) were evaluated. In 2009, no stunting was noted at Yoakum with any herbicide regardless of cultivar. At Lamesa, FlavorRunner 458 and Tamrun OL01 were stunted at least 6% with the 0.21 kg ha −1 rate of flumioxazin and 6 to 17% with the 0.07 and 0.14 kg ha −1 rate of imazapic. Tamrun OL02 was stunted by all rates of flumioxazin (5%) and imazapic (5 to 18%) while Tamrun OL07 was stunted by all rates of flumioxazin (6 to 12%) and imazapic (7 to 15%) with the exception of flumioxazin at 0.05 kg ha −1 . Flumioxazin did not have an effect on yield while all imazapic rates reduced yields when compared with the non-treated control. In 2010 at Yoakum, little (&lt;2%) or no herbicide stunting was noted on any cultivar and only imazapic at 0.14 kg ha −1 caused significant stunting (7%). No yield differences were noted between herbicides regardless of cultivar. At Lamesa, all cultivars were affected (6 to 9% stunting) by herbicide treatments. No peanut stunting was noted with flumioxazin at 0.05 kg ha −1 while imazapic at 0.04 kg ha −1 and flumioxazin at 0.11 kg ha −1 resulted in 4 and 6% stunting, respectively. Flumioxazin at 0.21 kg ha −1 and imazapic at 0.07 kg ha −1 resulted in 12% stunting and imazapic at 0.14 kg ha −1 stunted peanut 19%. Both Tamrun OL01 and Tamrun OL07 produced lower yields (≤6369 kg ha −1 ) than FlavorRunner 458 (7252 kg ha −1 ). Tamrun OL02 yields were intermediate (6889 kg ha −1 ). Peanut yields from herbicide treatments were not different from the nontreated control

Characterizing and Locating Seismic Tremor during the 2022 Eruption of Mauna Loa Volcano, Hawai’i, with Network Covariance

The 2022 eruption of Mauna Loa Volcano, Hawai’i, was accompanied by continuous seismic tremor that began about 30 min before and ended several days after the eruption. We characterize the amplitude history and frequency content of the tremor, and we use a network covariance‐based method to estimate its source location. The tremor exhibits multiple narrow spectral peaks between 1 and 3 Hz, and its amplitude varies through time in a spasmodic manner. Our location results track a northeast migration of shallow sources through the summit region in the first few hours of the eruption. For the remainder of the eruption, source locations cluster in the vicinity of the erupting vent in the northeast rift zone. We attribute the tremor source to gas dynamics in the upper reaches of a basaltic dike. However, limitations in instrumentation and knowledge of the subsurface velocity structure may preclude an assessment of the source mechanism. Our results illustrate the value of characterizing and locating tremor for tracking magma movement, and demonstrate a use for dense and calibrated seismic instrumentation on active volcanoes. The location method we use requires substantial parameter testing, reflecting the potential benefit of developing more flexible approaches toward real‐time automated assessment of tremor at volcanoes