Evaluation of elevated band height for basal bark triclopyr applications to Schinus terebinthifolia

Reduced hack and squirt (RHS) is a herbicide-injection technique that controls woody species with a limited number of hacks. When used with aminopyralid or aminocyclopyrachlor, the technique controls multistemmed shrubs such as Brazilian peppertree (Schinus terebinthifolia Raddi) and Surinam cherry (Eugenia uniflora L.). However, additional data are needed to compare its effectiveness on other woody invasive species against standard individual-plant treatment techniques. We compared RHS with aminocyclopyrachlor or aminopyralid administered with 0.5 ml of undiluted concentrate (240 g L−1) against traditional basal bark and cut stump techniques using triclopyr at 96 and 120 g L−1, respectively, on six invasive trees in Florida, USA. For all species tested, the RHS technique with aminocyclopyrachlor was not different or was more effective than basal bark or cut stump treatment with triclopyr. The RHS technique with aminopyralid was effective on certain species but did not control as many species as RHS with aminocyclopyrachlor or cut stump treatment with triclopyr. The RHS technique required significantly less time than cut stump treatment but was not different from basal bark treatment. Across all species, when compared with basal bark and cut stump treatment with triclopyr, the RHS approach resulted in reductions of average total herbicide mix applied by 98% and 89%, respectively. For herbicide active ingredient, when compared with basal bark and cut stump treatment with triclopyr, RHS resulted in reductions of 95% and 86%, respectively. These results indicate that when compared to conventional individual plant treatment (IPT) approaches with triclopyr, the RHS approach yielded a high level of target efficacy on a broad spectrum of species, comparable or shorter application times, and substantial reductions in herbicide mix and active ingredient applied. Future research should seek continued refinement of this technique for woody plant control on other troublesome invaders.

Brazilian peppertree (Schinus terebinthifolia Raddi) is a multistemmed shrub or small tree from South America that is invasive in Florida, Texas, Hawaii, and Australia. It forms multistemmed trunks with spreading branches that create dense thickets. State agencies in Florida manage it at annual costs of over $3 million, and individual plant treatment (IPT) techniques are widely used for control. Recent research testing novel hack and squirt approaches with aminopyralid and aminocyclopyrachlor and basal bark treatment with a new triclopyr formulation has shown these treatments are highly effective. However, they have not been evaluated at larger scales, which would be useful to land managers. Therefore, our objective was to compare the reduced hack and squirt technique using aminopyralid and aminocyclopyrachlor herbicides to basal bark treatment with triclopyr on a field scale. We used two contractor crews to apply treatments to twenty-four 0.2-ha plots. Treatments included aminocyclopyrachlor (120 g L−1) or aminopyralid (120 g L−1) applied with the reduced hack and squirt technique and triclopyr ester (108 g L−1) and triclopyr acid (34 g L−1) formulations applied with two basal bark treatment techniques. We confirmed that reduced hack and squirt significantly reduced the amount of herbicide and carrier applied compared with the basal bark treatments. By 540 d after treatment, aminocyclopyrachlor more effectively controlled S. terebinthifolia than aminopyralid with reduced hack and squirt and resulted in control comparable to that seen with either triclopyr basal bark treatment. These results verify reduced hack and squirt treatment with aminocyclopyrachlor and basal bark treatment with triclopyr acid as alternatives to basal bark treatment with triclopyr ester. Both resulted in significantly less herbicide use with comparable efficacy. This operational research approach has accelerated our understanding of novel IPT strategies and their implementation in the field.

Brazilian peppertree (Schinus terebinthifolia Raddi) is an aggressive shrub that infests more than 280,000 ha in Florida. Individual plant treatments (IPT), including basal bark and cut stump application with triclopyr butoxyethylester and triethylamine formulations, respectively, have been used for decades. While they are both effective, resprouting can occur, which requires retreatment for control. Recent research on other woody invasive plants has indicated additional non-crop herbicides used in natural areas can be effective with these IPT techniques and therefore warrant testing on S. terebinthifolia. In 2018 and 2019, basal bark and cut stump studies were conducted at Cape Canaveral Air Force Station in natural areas infested with S. terebinthifolia. In the basal bark application studies, we found aminocyclopyrachlor applied at 12 and 24 g L−1 and triclopyr acid applied at 34 and 69 g L−1 each provided 100% defoliation of multistemmed S. terebinthifolia individuals with a mean root collar diameter up to 20.2 cm at 360 d after treatment (DAT). These were not different from triclopyr ester applied at 96 g L−1. Imazamox applied at 30 g L−1 resulted in 86% defoliation at 360 DAT. However, we observed formulation incompatibility when imazamox was mixed with basal bark oil which may limit its utility. In cut stump studies, we found aminocyclopyrachlor and aminopyralid each individually applied at 6, 12, and 24 g L−1, resulted in stump mortality that was not different from the commercial standard triclopyr amine applied at 180 g L−1. Similar results were found for a triclopyr acid formulation applied at 86 and 172 g L−1 and imazamox applied at 60 g L−1. For both treatment techniques, we found that alternative treatments provided control at lower herbicide concentrations than triclopyr ester and amine commercial standards. These results advance our understanding of IPT and expand access to additional effective herbicide options for S. terebinthifolia management.

Basal bark treatment with triclopyr butoxyethyl ester is used to control woody invasive plants, including Brazilian peppertree (Schinus terebinthifolia Raddi). However, the ester formulation cannot be applied where standing water is present, which includes wetlands where S. terebinthifolia is found. In 2009, a low-volatile acid formulation of triclopyr was labeled for use in aquatic sites, which allows for basal bark applications when standing water is present. This formulation may have utility for controlling woody plants in standing water. However, anecdotal observations of injury to non-target plants following applications during periods of inundation have been reported. To address this, mesocosm studies were conducted to assess non-target injury through triclopyr root exudation or release from the surface of treated stems via flooding. Mesocosms contained S. terebinthifolia as the treated target, while sugarberry (Celtis laevigata Willd.), buttonbush (Cephalanthus occidentalis L.), and red maple (Acer rubrum L.) were included as non-targets. In the first study, the pathway of root exudation for non-target injury following triclopyr (34 g L−1) basal bark application was isolated with activated charcoal placed at the soil surface. In the second study, mesocosms were flooded to assess triclopyr release from the surface of treated stems and subsequent non-target injury. Defoliation of non-target species posttreatment was ≤8%, and triclopyr was detected at ≤5 µg L−1 in mesocosm wells when activated charcoal was present. Posttreatment non-target defoliation up to 92%, coupled with triclopyr concentrations in surface waters and wells as high as 4,637 µg L−1, indicated triclopyr movement as a result of flooding. Additionally, triclopyr non-target injury from soil activity independent of flooding was observed. These findings provide limited evidence of triclopyr root exudation but considerable evidence of triclopyr release during flooding following basal bark treatment and support a cautionary approach to basal bark application when standing water is present.

Invasive shrubs often present extremely difficult challenges for individual plant treatment approaches due to multiple basal stems with complex branching patterns. Basal bark and cut stump individual plant treatments have been the standard methods for managing large-statured shrubs, while hack and squirt has been disregarded as operationally too difficult. However, hack and squirt is a more discriminant treatment technique that may lead to a reduction in herbicide use. Here, we evaluated the speed, herbicide use, and performance of a reduced hack and squirt approach using single hacks per stem injected with 0.5 ml of either aminocyclopyrachlor (240 g L−1) or aminopyralid (240 g L−1) against conventional low-volume basal bark treatment with triclopyr ester (96 g L−1) and cut stump treatment with triclopyr amine (180 g L−1). The experiments were conducted on three subtropical shrub species: Eugenia uniflora, Lagerstroemia indica, and Schinus terebinthifolia. Across species, we found the reduced hack and squirt approach resulted in comparable treatment efficacy to basal bark and cut stump treatment, was faster than cut stump treatment, and used less herbicide and carrier than basal bark treatment. A single hack per stem is a significant shift for hack and squirt treatment, which typically employs a narrow or continuous spacing of hacks around the entire circumference of each stem. Future work should seek to clarify the applicability of this approach over a wide range of invasive shrubs.

Efficient transportation of freight as well as motorists requires effective control of vegetation on right-of-ways (ROW's). Traditionally on railroad ROW's, residual herbicides are applied early in the growing season with POST applications to restrict weed emergence. Field studies in central Illinois (three), Missouri (one), and Kansas (one) were established in 2015 and 2016 to compare fall single versus multiple application timings of residual herbicides from fall through the following summer. The objective was to optimize the timing of residual herbicides to minimize weeds over the greatest duration of the growing season. Residual herbicides were applied in the: fall (full rate), fall followed by spring (half-rates) spring (full rate), and spring followed by summer (half-rates). Spring/summer split applications resulted in consistent weed control throughout the growing season in four of five locations. Fall application at half-rates delayed the spring timing of spring half-rates up to 40 days compared to no fall application. Split programs extended the length of time that herbicides remained at active levels in the soil. In a separate study, management of an emerging invasive tree species along roadside ROW's was determined. Callery pear (Pyrus calleryana) has escaped cultivation and invaded undisturbed areas such as roadsides and pastures from the mid-west to eastern United States. Experiments were initiated in 2015-2017 to determine the response of herbicides delivered by foliar, basal bark, and cut-stump methods. Initiation of symptoms with foliar applied growth regulator herbicides was slow at 3 months after treatment (MAT); control at 12 MAT control ranged between 95 and 100 percent. Basal bark and cut-stump experiments were conducted on trees with a basal diameter between 10 and 15 cm. At 1 year after treatment (YAT) for basal bark treatments, triclopyr + aminocyclopyrachlor resulted in the highest control (57 percent). Remaining basal bark treatments resulted in 25 and 50 percent control. Cut-stump treatments involved application of herbicide on cambium tissue and effectiveness was high (95 to 100 percent at 1 YAT). In densely infested areas with small trees, a number of foliar herbicides can be effective. In areas with desirable species, Callery pear can be selectively removed using cut-stump applications. The use of basal applications may require different timing for initial application or sequential treatment.

Drift, dissipation and risk to wildlife following targeted herbicide applications on boreal transmission rights-of-way

Brazilian peppertree, Schinus terebinthifolia Raddi (Sapindales: Anacardiaceae), is an invasive tree in the Southeastern United States, Texas, California, and Hawaii. The Brazilian peppertree thrips, Pseudophilothrips ichini Hood (Thysanoptera: Phlaeothripidae), is a recently approved biological control agent for use within the US. The thrips have since been released in the field and are expected to reduce Brazilian peppertree performance. Pseudophilothrips ichini is likely to impact young trees but the impacts may vary based on thrips population size and tree age. To better understand the factors contributing to agent impact on young trees and P. ichini population growth, we measured the effect of P. ichini density (0, 4, 10, and 20 thrips) and tree age (3-, 4-, and 6-month-old plants), on tree performance and P. ichini productivity in the laboratory. Brazilian peppertree height and the number of growing tips were reduced across all age groups. However, the negative impact was more pronounced on the youngest trees, which had a reduction in the relative change in height of 171% and a 100% reduction in the number of growing tips. Pseudophilothrips ichini production was positively correlated with tree height (r = 0.44) and biomass (r = 0.56), but thrips relative production was similar across tree age. Results indicate that P. ichini have a great capacity for population increase regardless of starting density. Field studies are needed to corroborate these findings and identify barriers to agent success. This work aims to refine expectations of the impacts to Brazilian peppertree caused by P. ichini.

Honey locust is a deciduous tree that is now present throughout most of the United States. Fire suppression and introduction of honey locust into shelter belts has allowed honey locust to increase in pastures of mixed grass prairie. Because locust trees can produce abundant sprouts, mechanical measures also require herbicides to effectively control trees. Each year for 2 yr, trees were treated with one of five combinations of herbicides and application methods. Treatment combinations, on a v/v basis, included (1) triclopyr 25% + diesel 75% and (2) aminopyralid 5% + bark oil 95%, both applied to the lower 38 cm of basal bark including the root collar area of live trees, as well as (3) triclopyr 25% + diesel 75%, (4) aminopyralid 10% + water 90%, and (5) dicamba 33% + 2,4-D 2% + water 65%, all applied immediately to the outer cambium layer of cut stump surfaces. One year after treatment, aminopyralid applied as a basal bark or as a cut-tump treatment had the best control and averaged over 97% dead trees. The triclopyr + diesel cut-stump treatment had the fewest dead trees (just over 50%) and produced many new sprouts. In grazed pasture, treating cut tree surfaces with dicamba + 2,4-D + water or aminopyralid + water and treating standing live trees with a basal bark application of aminopyralid + oil are three effective control options. Triclopyr + diesel displayed better control on live standing trees with a basal bark treatment rather than as a cut-stump treatment.

Basal bark treatments involve the application of concentrated herbicide solution on each individual stem of targeted plants. When applied to stands of invasive plants with high stem densities, basal bark treatments may result in the use of large quantities of herbicide in a given area. The effect of basal bark treatments using a solution of 25% triclopyr herbicide and 75% methylated seed oil was tested on research plots located in six different groves of invasive fig, a densely stemmed, problematic invader of riparian forests in California. The experimental treatments resulted in application rates that were equivalent to 28 to 44 kg ae/ha, greatly in excess of the labeled maximum use rate of 9 kg ae/ha (8 lb/ac). At 175 d after application, soils near the fig trunks contained high levels of triclopyr residues (up to 6.6 ppmw), suggesting that the chemical made its way into soils during this period and was not completely degraded. Although the mortality of native plants transplanted into treated fig groves was low (up to 16%), it was significantly greater than the mortality experienced by native plants transplanted into untreated control sites (0%). Although effective in controlling invasive fig trees (> 99% mortality), the high herbicide application rates from basal bark treatment preclude the use of this treatment in large fig groves. These treatments may be appropriate, however, when fig groves are small or isolated enough to prevent overapplication on a per-area basis. In addition, neither limited basal bark applications of triclopyr (< 40% of stems treated) nor foliar spray treatments of 2% glyphosate were effective control measures. Further investigation is needed on ways to control large invasive fig groves.

We investigated ten honey samples from the Discovery Coast of Bahia, Brazil, to confirm the three predominant flower sources indicated by regional beekeepers: Brazilian peppertree - Schinus terebinthifolia Raddi; eucalyptus - Eucalyptus L'Hér. spp.; and velame - Croton L. spp.. The honeys were collected in five Southern Bahia municipalities - Belmonte, Eunápolis, Guaratinga, Itabela and Porto Seguro. The samples underwent acetolysis and, after slides mounting, the pollen types were identified and counted to determine the frequency classes. The pollen spectra revealed 31 pollen types in 27 genera and 17 families. The palynological analysis confirmed the predominant eucalyptus flower source indicated for four honey samples from Belmonte, Eunápolis, Itabela and Porto Seguro. Three honey samples previously indicated with predominant eucalyptus and velame flower sources had no predominant pollen. Eucalyptus predominated as the main flower source for another three samples previously indicated by beekeepers as Brazilian peppertree and velame. We conclude that regional honeys marketed as having a predominant flower source may have distinct botanical origin. This demands further research aimed at reviewing which bee plants provide resources for monofloral, bifloral and plurifloral honeys in the Bahian Discovery Coast.

Architectural form design is crucial to building indoor and outdoor natural ventilation, and elevated building design is one of the methods for improving the outdoor wind environment. Through Integrating computational fluid dynamics (CFD) simulation with architectural design, an informed decision for architectural design is provided for better architectural design schemes. CFD simulation was used to explore the impacts of elevated heights on the XJTLU Central Building's wind environment at the pedestrian height around the building. Results show that the elevated design of the building has a good effect on improving the wind environment at the pedestrian height of 1.5 m around the building. For this study case and similar height buildings, the elevated design can increase the wind speed of the 1.5 m pedestrian height in the windward area of the building when the elevated height is 2.4～3.0 m. When the elevated design height is above 3.0 m, the elevated design has little impact on the 1.5 m height wind speed at the windward area of the building. On this basis, the impact of various building heights and elevated widths on the pedestrian height wind speeds were explored. Results show that when the building height is between 24 and 72 m, increasing the building height can increase the wind speed at pedestrian height in the high wind speed area of the windward area, and gradually reduce the wind speed of the pedestrian height in the low wind speed at the windward area of the building. When the total height of the building and the elevated height is unchanged, results show that increasing the elevated width of the building can increase the pedestrian height wind speeds in the high wind speed area of the windward area and has no significant impact on the pedestrian height wind field distribution in the low wind speed area of the windward area.

Brazilian peppertree (Schinus terebinthifolia Raddi, Anacardiaceae) is an aggressive invasive species that occurs in peninsular Florida, USA. Current management techniques are expensive, require repeated application, and cause non-target damage in ecologically sensitive habitats. Calophya lutea Burckhardt and Calophya terebinthifolii Burckhardt & Basset (Hemiptera: Calophyidae) were found damaging Brazilian peppertree in Brazil. To determine if C. lutea and C. terebinthifolii are suitable biological control agents of Brazilian peppertree, host specificity testing was conducted in a quarantine laboratory. In total, 97 plant species were tested, and oviposition and gall initiation were evaluated under no-choice conditions. Calophya lutea and C. terebinthifolii oviposited on nine and five of the 97 plant species tested, respectively. The majority of the eggs were laid on Brazilian peppertree and complete immature development with adult emergence occurred only on Brazilian peppertree. Adult longevity and behavior were determined in a separated experiment on all non-target species on which Calophya oviposited during the host specificity experiment. Adult longevity was four to five times longer on Brazilian peppertree when compared to non-target species. Based on our results, we conclude that both C. lutea and C. terebinthifolii are host-specific and form galls and complete development only on Brazilian peppertree. Therefore, these agents are considered safe to release in Florida and should be incorporated into the ongoing biological control program.

Managers tasked with controlling invasive species require effective methods that are quick and easy to use without inflicting extensive nontarget damage, while also being compatible with other scheduled management responsibilities. Lonicera maackii (Amur honeysuckle) is a non‐native shrub that has invaded eastern and midwestern North American deciduous forests, altering ecosystem function and reducing biodiversity. This study explores prescribed fire and seasonal basal applications of triclopyr ester as control methods and examines the extent of nontarget damage. We used paired‐split plots to implement basal bark treatments in different seasons within burned and unburned units, and we tracked individual L. maackii to determine mortality and hyperlocal impacts of management. Basal bark treatments killed 98.4% of L. maackii across seasonal timings. Nontarget plant cover declined similarly for all herbicide application seasons, but there were some signs of recovery within 4 years, and the early‐ and late spring treatments were less affected overall. Species richness showed biologically small but statistically different declines across treatment times. Prescribed fire did not impact L. maackii mortality or interact with herbicide efficacy. Basal bark applications of triclopyr are an effective means of L. maackii control regardless of application timing, which allows managers to implement it at their convenience to avoid interfering with other management tasks that have time constraints.

The Cittadella di Alessandria (Italy) is a military fortification that was built in the 18th century. The site has recently been abandoned and is now colonised by weeds, including the invasiveAilanthus altissima. The aim of the study was to compare the efficacy of different herbicides (glyphosate, a mixture of aminopyralid + fluroxypyr and triclopyr + fluroxypyr) applied to cut stumps or to the basal bark ofA. altissima. For the cut stump application, plants were first cut at the base and then immediately sprayed and for the basal bark application, the lower 50 cm of the plants was sprayed with the herbicides; untreated cut plants were used as a control, for comparison. Two runs per study were carried out (in summer 2015 and in spring 2016). Efficacy was assessed up to 2018 by counting the resprouts and their height in the cut stump application and, for the basal bark treatment, by measuring the variation in the plant circumference after treatment. The cut stump treatment carried out in summer greatly reduced the number of resprouts, compared to the spring treatment, to less than one sprout per plant when aminopyralid + fluroxypyr was used, and its efficacy lasted for about two years. The basal bark treatment did not control the species, but lower levels of variation in circumference and greater mortality were detected in plants treated with aminopyralid + fluroxypyr. Considering the high level of infestation of the site and the high risk of plant resprouting, repeated cut stump treatments with aminopyralid + fluroxypyr would be preferable to eradicate this invasive species.