Crop, Forage and Turfgrass Management最新文献

Pyraclonil is a new herbicide to control weeds in California water-seeded rice (Oryza sativa L.). The objectives of this research were to evaluate weed control and rice response from pyraclonil applied alone at different timings and when applied in combinations with other herbicides. In one field study, pyaclonil was applied at 0.3 lbs a.i. ac⁻¹ on pre-seed bare ground, 1-inch flood, 4-inch flood and 3 days after flooding in water-seeded rice. In another study, pyraclonil was applied at 0.3 lbs a.i. ac⁻¹ at day of rice seeding and followed by various registered herbicides. Pyraclonil applications resulted in similar weed control across timings. Pyraclonil provided greater than 92% control of smallflower umbrella sedge (Cyperus difformis L.) and broadleaf weeds but less than 60% control of ricefield bulrush [Schoenoplectus mucronatus (L.) Palla] at 42 days after treatment. Watergrass (Echinochloa spp.) control was achieved with pyraclonil if applied before emergence. Early-season rice injury from pyraclonil was observed; however, rice appeared uninjured later in the season. The addition of other herbicides after a pyraclonil application increased weed control levels across weed species and resulted in grain yields from 6,925 to 8,623 and 9,182 to 10,865 lbs ac⁻¹ in 2019 and 2021, respectively. Pyraclonil provides early-season weed control and, when incorporated with other herbicides, will be a useful herbicide in water-seeded rice.

Golf course superintendents may use bensulide to control annual grassy weeds and carfentrazone-ethyl (CE) to control silvery-thread moss (Bryum argenteum Hedw.) in creeping bentgrass putting greens. Creeping bentgrass injury has been reported if CE is applied soon after treatment with bensulide and the safe application interval varies as much as 68 days. Our goal was to improve the precision of recommendations for safe application of CE following bensulide, considering both CE rate and timing. We used a factorial treatment structure that included (1) bensulide or no bensulide, (2) three rates of CE, and (3) nine CE application timings in 2018 and 2019 at locations in Nebraska and Ohio. Because of limited effects in 2018, different CE rates and application timings were used in 2019. Significant creeping bentgrass injury was only observed at 6.7 or 13.4 fl oz acre⁻¹ rates of CE that were applied within 3 days of applying bensulide. Even the 13.4 fl oz acre⁻¹ rate (a 2× rate) of CE did not injure creeping bentgrass when applied at least 7 days after applying bensulide. The 2.0 fl oz acre⁻¹ rate of CE never injured creeping bentgrass, even when applied the same day as bensulide. Cultivar, management, and environmental differences may influence whether subsequent application of bensulide and CE injures creeping bentgrass. Based on the environmental/cultural conditions and cultivars used in this research, golf course superintendents should expect little to no injury when CE is applied at least 1 week after applying bensulide.

High-quality forages can benefit from being harvested as baleage when the environmental conditions are not favorable for dry hay production. Currently, it is recommended that baleage should be fed within 9-months post-harvest; however, mild winters can reduce the demand for these stored forages. Data are limited on the changes in nutritive value of baleage stored beyond the recommended timepoint. Therefore, the objective was to determine the effect of storage length on nutritive value of forage harvested and stored as baleage. This study evaluated baleage harvested from 2016 to 2018 in Tifton, GA, consisting of either bermudagrass (Cynodon dactylon L. Pers.), or a mixture of bermudagrass and alfalfa (Medicago sativa L.). Baleage was sampled for nutritive value analysis at 6-weeks and 9- and 12-months post-harvest, with a subset of bales sampled at 24 months. Regardless of forage, crude protein, total digestible nutrients, and in-vitro dry matter digestibility at 48 h were not impacted in bales sampled up to 12-months post-harvest (p > 0.07). However, acid detergent fiber increased when baleage was stored beyond 6 weeks but did not change from 9 to 12 months (p < 0.01). In the subset of bales stored up to 24-months post-harvest, all nutritive value parameters evaluated were negatively impacted (p < 0.01). The prolonged storage period may negatively affect the baleage plastic integrity, resulting in a decline in nutritive value if anaerobic conditions are not maintained. Future research is warranted to evaluate the changes in the fermentation profile of baleage under extended storage conditions.

Preemergence herbicides (PRE) have become integral for weed control in cotton (Gossypium hirsutum L.), especially with the prevalence of glyphosate-resistant Palmer amaranth (Amaranthus palmeri S. Wats.). However, PRE herbicides have the potential to injure cotton seedlings. Previous research has shown that a larger seed size can compensate for early season stresses which could mitigate potential PRE herbicide injury. In this study, we evaluated growth and yield of two cotton varieties with different seed sizes (large and small) in response to three PRE herbicides alone and in combination. Percent visual injury, biomass, plant heights, stand counts, lint yield, and fiber quality were obtained to make comparisons between seed sizes and PRE treatments. In both years, the large-seeded variety had a higher biomass at 3-leaf stage. However, both varieties had “grown out” of the herbicide injury at 42 days after planting and the early season vigor of the larger seed did not result in higher lint yield. The small-seeded variety had greater yield in both years of the study. This may be due to the genetics or yield potential of the small-seeded variety, or bolls containing smaller seeds typically have a greater number of seeds with more opportunity for lint production. Cotton treated with diuron had the most visual injury and decreased biomass. The results from this study will allow growers to make more informed decisions with regards to seed size, vigor, and PRE herbicide choices. If crop injury is likely, a larger seeded cotton variety may mitigate potential early season injury; however, seed size did not have an impact on final lint yield.

Canola (Brassica napus) and pennycress (Thlaspi arvense L.) are winter oilseed crops that can be used to create sustainable aviation fuel. They have been grown successfully in the Upper Midwest and Great Plains and are garnering interest in the Mid-South. A field study was conducted in Tennessee to determine management practices and average yields expected for the region. From this study, a budget and breakeven analysis was conducted. Budgets were created for tilled and no-till canola and pennycress systems. Based on average yields obtained and projected oilseeds prices, canola systems are potentially profitable, while pennycress systems are not. However, breakeven prices were highly variable between years, locations, oilseed species, and tillage type. Canola has been relatively established in the region and can be promoted to growers as a profitable crop. Presently, the adoption of pennycress in the Mid-South is not recommended without further research on best management practices, breeding efforts for higher yielding varieties, and the creation of a viable market for sale.

Poultry litter (litter) is a nutrient dense fertilizer that increases nutritive value and yield in pastures in the mid-southern US. Nutrient losses due to runoff and nitrogen volatilization are common when broadcasting litter. As such, incorporating litter below the soil surface (subsurface) was evaluated in comparison to broadcasting in 2021 and 2022 by quantifying yield and nutritive value of annual forages. The study was a randomized complete block design with three forage treatments—sorghum-sudangrass only (Sorghum bicolor L.), cowpea only (Vigna unguiculata L.), and their mixture, and three litter application methods (broadcast, subsurface, and a no litter control). Litter was applied in 2021 only as biennial application is common to save on application cost. Nutritive analyses included neutral detergent fiber and crude protein (CP). Partial budgeting led to relative profitability estimates by accounting for yield and cost differences across treatments. In comparison to the second-highest yielding forage mixture, sorghum-sudangrass yielded 4.5%–18.4% more regardless of litter application method. The forage mixture did not improve forage nutritive value, as cowpea were vastly outcompeted and did not average more than 5% of the total forage harvested in mixtures. Cowpea yields did not benefit from litter application. Subsurface application resulted in 8%–10% greater CP content compared to no litter and broadcast litter, respectively, across all forage species. Sorghum-sudangrass with subsurface applied litter earned nearly $70/acre more than sorghum-sudangrass with broadcast litter, the next highest treatment combination, and, with lesser nutrient loss.

Annual bluegrass (Poa annua L.) is the most troublesome weed on golf courses in the US. Many agronomic practices intended to promote high-quality playing surfaces favor the growth and development of annual bluegrass, resulting in high weed pressure. One commonly used herbicide for annual bluegrass control on golf courses is ethofumesate, which is a very long chain fatty acid inhibitor. Annual bluegrass resistance to this herbicide is documented and confirmed in grass seed production systems, but potential resistance on golf courses was previously unknown. The objective of this study was to determine the frequency and magnitude of potential ethofumesate resistance from a sample of US golf courses. A dose-response experiment was initiated at Purdue University using 30 annual bluegrass populations collected from Alabama, California, Indiana, and Oregon golf courses. Ten ethofumesate doses included 0, 0.5, 1.0, 2.5, 5.0, 7.5, 10.0, 15.0, 20.0, and 40.0 lb a.i. acre⁻¹, with 1.0 to 2.0 a.i. acre⁻¹ as the standard label application rate for perennial ryegrass turf. A low level of resistance (R/S < 3) was found in several populations collected in each state. The mean effective dose necessary to kill 50% of the populations (ED₅₀) was 5.1, 9.2, 3.5, and 3.4 lb a.i. acre⁻¹ for populations from Alabama, California, Indiana, and Oregon, respectively. The most resistant population originated from California, with an ED₅₀ of 13.2 lb a.i. acre⁻¹. To reduce selection pressure from ethofumesate populations, golf course superintendents are encouraged to develop site-specific weed control programs that rotate herbicide sites of action, as well as utilize diverse control tactics.

Lentil (Lens culinaris Medik.) production has increased exponentially in Montana in the last two decades. However, there are important gaps in knowledge on best management practices for lentil. Agronomic recommendations are based on performance of old cultivars outside of the area for seeding rate, and on anecdotal evidence for proper roll timing, particularly since the widespread adoption of no-till farming. Replicated field experiments were conducted at three sites during the 2019, 2020, and 2021 growing seasons in Montana to determine the impacts of roll timing and seeding rate on lentil yield and identify best practices. Overall, rolling at emergence and at the 10-leaf stage decreased yields by 5% and 8%, respectively, but rolling just after planting or at the early vegetative stage (two- to four-leaf stage) did not decrease yields. Higher yields were achieved at higher seeding rates, with yields increasing between 6 and 52 lb ac⁻¹ for each additional plant established per square foot, but emergence rates were variable and relatively low, so a higher seeding rate may be necessary to achieve plant densities above 12 plants ft⁻² in this region. In five out of nine site years, the largest partial economic returns were achieved with 22.5 or 30 live seeds ft⁻² seeding rate, corresponding to achieved plant densities of 12 to 16 plants ft⁻². It was generally economical to increase seeding rate from 15 to 22.5 live seeds ft⁻², thus increasing average achieved plant density from 8 to 13 plants ft⁻², except when seed costs were high (>$0.45 lb⁻¹) combined with low market prices (< $0.20 lb⁻¹).