A comparison of different chemical control application methods for managing Elaeagnus pungens in South Carolina

Off-Target Herbicide Deposition Associated with Treating Individual Trees

European gorse (Ulex europaeus L) is a persistent, declared weed (Category 1) of South Africa. Current distribution is limited to the moist, high altitude regions of the Drakensberg (KwaZulu Natal Province) and Amatola (Eastern Cape Province) mountains. Gorse poses a threat to the plant diversity of forests, where it could establish itself quickly and occupies the site indefinitely. Once established, gorse can be difficult to eradicate, as it resprouts if cut or burnt and no herbicide was registered in South Africa at the time of this research on its control. The objective of this investigation was therefore to evaluate selected herbicides at various concentrations using different application techniques. Picloram and triclopyr ester proved the most effective and consistent across all application methods, while imazapyr is also recommended for cut-stump treatment. As a result of this research, both picloram and triclopyr were registered under Act 36 (1947) for the control of European gorse by means of cut stump and foliar treatment.

Field trials were conducted at the Coastal Plain Experiment Station in Tifton, GA, from 2000 to 2003 to study the effects of herbicide placement on weed control and cantaloupe injury. Herbicides halosulfuron (0.036 kg ai/ha), sulfentrazone (0.14 and 0.28 kg ai/ha), clomazone (0.6 kg ai/ha), and a nontreated control were evaluated. Methods of herbicide application were preplant incorporated (PPI) under the polyethylene mulch before transplanting, posttransplanting over-the-top (POST-OTT), and posttransplanting-directed (POST-DIR) to the shoulders of polyethylene-covered seedbeds. Across all herbicide treatments, PPI and POST-DIR applications were the least injurious, with POST-OTT applications the most injurious. In general, sulfentrazone (0.28 kg ai/ha) was the most injurious herbicide and halosulfuron the least injurious, regardless of herbicide placement. Halosulfuron effectively controlled yellow nutsedge and provided versatility in methods of application, with minimal injury to transplanted cantaloupe. Nomenclature: Clomazone; halosulfuron; sulfentrazone; yellow nutsedge, Cyperus esculentus L. #3 CYPES; cantaloupe, Cucumis melo L. Additional index words: Clomazone, halosulfuron, plasticulture, sulfentrazone. Abbreviations: POST-DIR, posttransplanting-directed; POST-OTT, posttransplanting over-the-top; PPI, preplant incorporated.

Russian thistle is a severe problem in fields after crop harvest in the Pacific Northwest (PNW) and is controlled either by tillage or broadcast applications of various herbicides. A study was conducted in Washington in 2000 and 2001 at four sites to compare the efficacy of two herbicide treatments applied with a light-activated, sensor-controlled (LASC) sprayer and a conventional broadcast sprayer for postharvest Russian thistle control. Additionally, simple economic comparisons, excluding fixed costs, were made among herbicide treatments and application methods. Both herbicide applicators controlled Russian thistle similarly within each herbicide treatment. Weed control was unacceptable (≤ 75%) when glyphosate plus 2,4-D was applied with either applicator. In contrast, Russian thistle control was > 90% with paraquat plus diuron regardless of applicator. The overall reduction in chemical use was 42% with the LASC compared with the broadcast applicator when averaged over the four sites. Herbicide and surfactant cost savings, using 2007 prices for the LASC compared with the broadcast applicator, ranged from $6.68/ha to $18.21/ha with the paraquat plus diuron treatment and averaged $13.27/ha less for the four sites. The use of the LASC for postharvest Russian thistle control can reduce growers' input costs, increase growers' profits, and improve environmental quality by reducing the amount and area of a restricted-use chemical. Nomenclature: Glyphosate, 2,4-D, paraquat, diuron, Russian thistle, Salsola tragus L

Forests in Mauritius are facing an alarming rate of encroachment by alien plant species which are changing the ecosystem function, equilibrium and composition of species and richness. Mauritius being a small tropical island is one of the recently colonized areas of the world where only a few descriptions of species composition and diversity exist. Invasive plant species are controlled by mechanical, chemical and biological methods. Efficient herbicide and suitable application methods were assessed for the control of Tabebuia pallida (Tecoma) in a forest area managed by the National Parks and Conservation Services (Mauritius). Effectiveness of herbicides to ringed barks showed Round-up (100 %) to be most effective compared to Triclon (73%) and Tordon 101 (40%). Drastic changes were observed with Roundup, irrespective of the application methods used. Significant differences were found among cut stump, ring barking and drilling application methods. Cut stump method was much more effective compared to the other two treatments. Ring barking also proved to be successful to some extent. Application of herbicides through drilling was ineffective. The use of herbicides was a significant factor in the death rate of the invasive species.

Elaeagnaceae are worldwide distributed plant which native mainly to subtropical regions of Asia, North America, southeastern Europe and Australia. The use of Elaeagnus has been known for a long time, in addition to fresh consumption, many species of Elaeagnus are widely used in Juice, herbal tea, wine, soup, sauce, dessert, candy, pudding, ice cream topping, fruit leather, jam and jelly. Along with their edible values, many species of Elaeagnus including Elaeagnus triflora, Elaeagnus umbellate, Elaeagnus Pungens, Elaeagnus angustifolia L., Elaeagnus x ebbingei and Elaeagnus multiflora has multiple used in folk medicine as anti-inflammatory, muscle relaxant, antipyretic, analgesic, astringent and antiulcer agent. Many Elaeagnus species have shown as rich in many bioactive components and known as strongly tanniniferous as well as many other compounds including indole alkaloids, sinapinic acid, flavonols, pentacyclic triterpenes and L-quebrachit. Wild Elaeagnus plants provides wildlife cover and introduce many environmental benefits for biodiversity maintenance and revegetation process. Many species has ability to fix atmospheric nitrogen and has very important role for the process of soil erosion prevention.

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.

Scotch broom is an invasive leguminous shrub in California and other Pacific Northwest states, as well as New Zealand and Australia. It is highly competitive in forest and shrub communities and can significantly impact reestablishment of conifer forests. The objective of this experiment was to evaluate mechanical methods (Weed Wrench, lopping), several herbicides, and herbicide application techniques for control of Scotch broom in a premontane site in California. Three herbicides were evaluated (glyphosate, imazapyr, and triclopyr ester) for canopy reduction using foliar, drizzle, and basal bark treatments. All treatments were made in both fall and late spring. In addition, we conducted a cost analysis of the various herbicide treatments and application methods. Results indicate that both mechanical treatments were effective, but their optimum timing depended on soil moisture conditions. In addition, there were no significant differences among herbicides at both timings, among all rates, and for any application method. All herbicides provided effective control of Scotch broom. However, the cost analysis demonstrated that the drizzle application method with glyphosate was the most cost-effective treatment, due to low herbicide cost and reduced labor requirements. These results provide several options for Scotch broom control and give land managers considerable flexibility with timing, herbicide, and application technique in their management programs.

Several plant species that are invasive in natural areas of public lands also occur on private property. Invasive plants on private property that thrive within both landscaped and surrounding natural areas can serve as a source of infestation to other natural areas. Therefore, property owners are encouraged to remove invasive plant species from both areas. This 5-page fact sheet is a major revision that discusses different herbicides, hand-pulling, stump grinding, foliar herbicide application, cut stump herbicide application, basal bark herbicide application, hack-and-squirt, frill, or girdle herbicide application, licenses and training, and control of specific invasive plants. Written by K. A. Langeland and S. F. Enloe, and published by the UF May 2016. http://edis.ifas.ufl.edu/ag259

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.

Greenhouse and field studies were conducted to determine tolerance of tomato to halosulfuron, imazosulfuron, and trifloxysulfuron herbicides applied through drip irrigation. In greenhouse studies, PRE- and POST-applied trifloxysulfuron caused greater tomato injury (14 and 54% injury, respectively) than PRE- and POST-applied halosulfuron (5 and 26% injury, respectively) or imazosulfuron (5 and 23% injury, respectively). All herbicide treatments in the greenhouse studies caused greater injury to tomato than the nontreated. Greater tomato injury was observed in the greenhouse from herbicides applied POST than when soil applied. Tomato injury from POST-applied halosulfuron, imazosulfuron, or trifloxysulfuron followed a linear relationship, with tomato injury increasing with increasing herbicide rate. Tomato photosynthetic rate did not differ among the herbicide treatments (32.7 to 55.0 μmol m−2s−1) and the nontreated (38.0 to 55.0 μmol m−2s−1). At 5 to 16 days after treatment (DAT), tomato treated with imazosulfuron POST (0.26 to 0.46 cm s−1) or trifloxysulfuron POST (0.27 to 0.51 cm s−1) had lower stomatal conductance compared to the stomatal conductance of the nontreated tomato (0.65 to 0.76 cm s−1). Chlorophyll content did not differ among treatments at 0 to 6 DAT. At 7 to 12 DAT, tomato treated with imazosulfuron POST (34.0 to 40.1 SPAD) and trifloxysulfuron POST (35.0 to 41.6 SPAD) had lower chlorophyll content compared to the nontreated (39.1 to 48.1 SPAD). In 2008 and 2009 field studies, no tomato injury was observed. Herbicide, herbicide application method, and herbicide rate had no effect on tomato height (73 to 77 cm 14 DAT, 79 to 84 cm 21 DAT) and total fruit yield (62,722 to 80,328 kg ha−1).

Invasive woody perennials pose an immense threat to the diversity and function of many ecosystems, including forests in the eastern United States. While herbicide treatments have proven effective in controlling many plant invasions, there is considerable interest in the refinement of herbicide prescriptions to improve efficacy and prevent non-target damage. Adjuvants are widely utilized to improve herbicide efficacy, but research on novel adjuvants is often lacking. Furthermore, adjuvant research has generally focused on enhancement of foliar herbicide absorption, and few studies focus on adjuvant utility for other herbicide delivery techniques such as cut stump treatments. We evaluated 2XL—a cocktail of cellulase enzymes derived from fungi—as a potential herbicide adjuvant for use with glyphosate applied in a cut stump treatment due to its ability to degrade a key component of cell walls. We conducted a field experiment using the cut stump method of treatment (cut surface treated with herbicide) on a problematic invasive shrub, Amur honeysuckle [Lonicera maackii (Rupr.) Herder]. We tested combinations of three concentrations of 2XL with five concentrations of glyphosate and hypothesized that low concentrations of glyphosate combined with 2XL would be as effective in limiting the resprouting of L. maackii as higher concentrations of glyphosate without the enzymes. Our results indicated that 2XL did not improve glyphosate efficacy for reducing the number of resprouting stems or the length of the longest resprouting stem within the same or following year as treatment. Limited data indicated the combination of 2XL and glyphosate applied at 30 g L−1 slightly increased resprouting in the year following treatment. While 2XL did not improve glyphosate efficacy, our results showed effective control of L. maackii at the lowest concentration of glyphosate tested (30 g L−1), suggesting that concentrations lower than those typically applied may be effective in controlling L. maackii within parameters similar to those tested here.

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.

Invasive shrubs like Tamarix spp. are ecological and economic threats in the U.S. Southwest and West, as they displace native vegetation and require innovative management approaches. Tamarix control typically consists of chemical and mechanical removal, but these methods may have negative ecological and economic impacts. Tamarisk leaf beetles (Diorhabda spp.) released for biocontrol are becoming increasingly established within Western river systems and can provide additional control. Previous Diorhabda research studied integration of beetle herbivory with fire and with mechanical management methods and herbicide application (e.g., cut stump), but little research has been conducted on integration with mowing and foliar herbicide application, which cause minimal soil disturbance. At Caballo Reservoir in southern New Mexico, we addressed the question: “How does Tamarix respond to chemical and mechanical control when Diorhabda is well established at a site?” A field experiment was conducted by integrating mowing and foliar imazapyr herbicide at standard (3.6 g ae L−1 [0.75% v/v] and low (1.2 g ae L−1 [0.25% v/v]) rates with herbivory. Treatments were replicated five times at two sites—a dry site and a seasonally flooded site. Beetles and larvae were counted and green foliage was measured over 2 yr. Mowing and full herbicide rates reduced green foliage and limited regrowth compared with low herbicide rate and beetles alone. Integrating conventional management such as mowing and herbicide with biocontrol could improve Tamarix management by providing stresses in addition to herbivory alone.

HERBIGATION IN A CHERRY ORCHARD – EFFICIENCY OF PENDIMETHALIN