Foliar Herbicide Applications Research Articles

Seed banks and post‐fire recovery of invasive alien Metrosideros excelsa in South Africa: Implications for control

AbstractThe New Zealand bottlebrush, Metrosideros excelsa (Myrtaceae), was introduced into South Africa in the 1940s as an ornamental plant and subsequently naturalized in coastal parts of the Cape Floristic Region. Knowledge of M. excelsa's propagule pressure and response to fire in South Africa can inform evaluation of the species' invasion potential and management. We assessed M. excelsa's canopy and soil seed banks in burnt and unburnt stands; and post‐fire regeneration via reseeding and resprouting in relation to fire severity and tree size. Soil seed banks were assessed using an emergence technique, but no seedlings emerged from soil collected under burnt or unburnt plants suggesting that the species does not maintain a viable soil‐stored seed bank or germination triggers were not met (though unlikely). The annual seed crop in the canopies of unburnt trees was approximately 0.5–23 million seeds per tree. Viability, assessed through tetrazolium stain testing, of canopy‐borne seeds on unburnt trees was 18%, whereas a canopy fire, ranging in severity from low to extreme, killed all canopy‐borne seeds. Fifteen months post‐fire, the seedling to pre‐fire (live) tree ratio was 0.01, whereas 43% of burnt trees survived via basal resprouting. Fire severity had a non‐linear effect on tree survival (survival was highest after medium and high fire severity and lowest after low and extreme fire severity), while larger trees were more likely to survive fire. These results suggest that even low‐severity (safe) burning may be a useful control measure as it kills canopy‐borne seeds and causes substantial mortality, particularly of smaller trees. An opportunistic evaluation of an uncontrolled (no comparison with untreated individuals) foliar herbicide application to post‐fire resprouting individuals also showed considerable (91%) mortality. However, rigorous herbicide trials (also with herbicide in conjunction with burning) are required to inform the management of M. excelsa.

Conservation management of an abandoned copra plantation at Palmyra Atoll, Northern Line Islands, Pacific Ocean

Coconut palms (Cocos nucifera) cultivated for copra are agricultural resources on many of the world’s low-lying tropical oceanic islands where they provide sustenance and economic value to human communities. However, coconut palms, when dominant in island plant communities, can outcompete native plants for above- and below-ground resources. Furthermore, when coconut palms displace native plant species preferred by seabirds as roosting and nesting habitats, they may disrupt beneficial nutrient pathways in both marine and terrestrial ecosystems. At Palmyra Atoll, located in the Northern Line Islands, Pacific Ocean, evaluation of three methods for controlling coconut palm seedlings (foliar herbicide application, cut-stem, and cut-stem combined with herbicide) showed that mortality was highest with the cut-stem combined with herbicide application. A comparison of herbicide volumes injected directly into stems of mature palms showed that mortality increased with herbicide volume; an injection of 10 ml of undiluted Roundup CustomTM herbicide (53.8% glyphosate) achieved 100% mortality within 8 months.

Low carrier volume herbicide trials and UAAS support management efforts of giant salvinia (Salvinia molesta): a case study

AbstractExpanding the current aquatic herbicide portfolio, reducing total spray volumes, or remotely delivering herbicide using novel spray technologies could improve management opportunities targeting invasive aquatic plants, where options are more limited. However, research on giant salvinia (Salvinia molesta Mitchell) response to foliar herbicide applications at carrier volumes ≤140 L ha−1 is incomplete. Likewise, no data exist documenting S. molesta control with unoccupied aerial application systems (UAAS). Following the recent >100-ha incursion of S. molesta in Gapway Swamp, NC, a case study was developed to provide guidance for ongoing management efforts. In total, three field trials evaluated registered aquatic and experimental herbicides using a 140 L ha−1 carrier volume. Select foliar applications from UAAS were also evaluated. Results at 8 wk after treatment (WAT) indicated the experimental protoporphyrinogen oxidase inhibitor, PPO-699-01 (424 g ai ha−1), in combination with endothall dipotassium salt (2,370 g ae ha−1) provided 78% visual control, whereas control when PPO-699-01 (212 g ai ha−1) was applied alone was lower at 35%. Evaluations also showed diquat (3,136 g ai ha−1) alone, glyphosate (4,539 g ae ha−1) alone, and metsulfuron-methyl (42 g ai ha−1) alone achieved 86% to 94% visual plant control at 8 WAT. Sequential foliar applications of diquat, flumioxazin (210 g ai ha−1), and carfentrazone (67 g ai ha−1) at 6 wk following exposure to in-water fluridone treatments were no longer efficacious by 6 WAT due to plant regrowth. Carfentrazone applications made from a backpack sprayer displayed greater control than applications made with UAAS deploying identical carrier volumes at 2 WAT; however, neither application method provided effective control at 8 WAT. Additional field validation is needed to further guide management direction of S. molesta control using low carrier volume foliar applications.

Fluctuation in amino acids content in Triticum aestivum L. cultivars as an indicator on the impact of post-emergence herbicides in controlling weeds.

This study was carried out in a demonstrated field in El-Sharkia Governorate, Egypt, during the winter of season 2020 to evaluate the leverage of four post-emergence herbicides i.e., tribenuron-methyl, clodinafop- propargyl, pyroxsulam and pinoxaden compared to control on total protein and amino acid contents in three wheat cultivars (Shandwel 1, Giza 171, and Sakha 95). Generally, the use of foliar herbicides led to a significant decrease in essential, non-essential amino acids and protein contents. However, tribenuran-methyl herbicide signifcantly increased the levels of proline, glycine, arginine, and histidine, but cystine and threonine not affected as compared to control. On the other hand, foliar herbicide application was significantly increased physiological , biochemical parameters and yield of Shandweel cultivar as compared to the other varieties. The physiological and biochemical models of dual-herbicide-tolerant wheat cultivars add to our understanding of the crop. In recent agricultural systems, herbicide tolerant plants are important for long-term weed management. Therefore, the study recommended the safely usage of Tribenuran-methyl as foliar herbicide in weed managment.

English

Parthenium weed is a noxious invasive species that has negative effects on agriculture and also causes allergic reactions in humans. The goal of this study was to evaluate several management strategies for parthenium weed and assess the suitability of each control measure for farmers, and other stakeholders in Uganda. Field experiments were conducted in a completely randomized design, and the quadrat sampling method used to assess the effect of mulching, foliar application of table salt solution, hand pulling, slashing, hand hoeing, foliar herbicide application, and integrated weed management on parthenium plant populations. All tested weed management strategies except foliar herbicide application significantly (Pï‚£0.05) reduced parthenium plant populations, with parthenium weed counts for treated plots reducing on subsequent data collection days. The experimental data showed that parthenium plant populations increased for the untreated plot overtime. The authors recommend that a combination of multiple weed control measures (integrated weed management) are utilized for effective management of parthenium weed in Uganda to reduce limitations that result when one management strategy is used singly. This study informs farmers, the general public, and researchers how to effectively control parthenium weed, contributing to reduction of the numerous negative effects of parthenium weed on human livelihoods. Key words: Agriculture, invasive, management, noxious, parthenium weed, Uganda. &nbsp

A preliminary field trial to compare control techniques for invasive Berberis aquifolium in Belgian coastal dunes

Non-native Berberis aquifolium is an invasive species in Belgian coastal dunes. With its strong clonal growth through suckers, this evergreen shrub outcompetes native species and affects dune succession. To prevent further secondary spread and mitigate its impact, there was an urgent need for knowledge on the effectiveness of control measures, both at the plant and habitat level. Here, we report on a first control experiment. Individual B. aquifolium clones were subjected to one of four treatments (manual uprooting, foliar herbicide application, stem cutting followed by herbicide or salt application), with regrowth being measured up to one year after treatment. We analyzed the relationship between kill rate, treatment, dune area, plant volume and number of plant stems using a generalized linear model. Berberis aquifolium plants proved most susceptible to foliar herbicide application (5% glyphosate solution), resulting in 88% (64%–97%) of the clones dying after treatment. The predicted kill rate decreased with an increasing number of stems under all treatments. We discuss the limitations of our experiment and the potential for actual field application of the different treatments. We present some guidelines for future control that may become further refined as experience builds up and we provide some recommendations for tackling invasive alien species in Atlantic dune ecosystems.

Integrating conventional management methods with biological control for enhanced Tamarix management

AbstractInvasive 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.

Herbicides to Kill Invasive Trees in Home Landscapes and Surrounding Natural Areas

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

Integrated Strategies for Management of Perennial Weeds

Multiple weed control strategies employed in combination can often aid the successful management of perennial weed species. This review article provides examples of integrated control programs that could aid in the management of several invasive perennial weed species that are problematic in the Pacific Northwest and elsewhere in North America. The development of an integrated management control program for wild chervil, a relatively recent invader to the Pacific Northwest of the United States and adjacent Canada, provides an example for this process. Through use of mechanical (mowing and tillage), cultural (establishment of competitive vegetation), and chemical (specific herbicides) strategies, control of this short-lived perennial species was greatly improved as compared to foliar herbicide applications alone. Such integrated strategies have been shown to enhance control of many perennial weed species, while potentially reducing the amount of herbicide applied, lessening the possibility of injury to adjacent desirable vegetation and increasing the stability of the ecological community at the site.

The weed composition in an orchard as a result of long-term foliar herbicide application

<p>The weed composition and the dominance of individual species occurring in an orchard were assessed at the Research Station of the Wrocław University of Environmental and Life Sciences, Poland, during the first 10 years after orchard establishment. ‘Ligol’ apple trees were planted in the spring of 2004 (3.5 × 1.2 m). Foliar herbicides were applied in 1 m wide tree rows twice or three times per each vegetation period. In the inter-row spaces, perennial grass was maintained.</p><p>Ten years of maintenance of herbicide fallow contributed to a change in the weed composition in the orchard. It changed as a result of different responses of the most important weed species to the foliar herbicides. Total suppression of <em>Elymus repens</em> was observed in the first year after planting the trees. <em>Convolvulus arvensis</em>, <em>Cirsium arvense</em>, and other perennial weeds, completely disappeared in the succeeding periods. The maintenance of herbicide fallow did not affect the abundance of <em>Taraxacum officinale</em>. The percentage of the soil surface covered by <em>Trifolium repens</em> and <em>Epilobium adenocaulon</em>, perennial weeds with considerable tolerance to post-emergence herbicides, increased during the fruit-bearing period of the trees. The abundance of these weeds was significantly reduced only in the rows with the stronger growing trees on the semi-dwarf P 2 rootstock. <em>Stellaria media</em> was the dominant annual weed. <em>Senecio vulgaris</em>, <em>Poa annua</em>, <em>Capsella bursa-pastoris</em>, and <em>Lamium</em> spp. were also frequently observed. A significant increase in the abundance of annual and perennial weeds was found in the tree rows as a result of improved water availability after a period of high precipitation.</p>

Effects of glyphosate on the bacterial community associated with roots of transgenic Roundup Ready® soybean

Introduction of glyphosate-resistant soybean plants into agricultural systems has greatly increased the application frequency of glyphosate. Because glyphosate is able to inhibit 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) not only in plants but also in different microorganisms, its application could lead to shifts in rhizosphere microbial communities in farming soils. In this study, greenhouse experiments were conducted with the objective to evaluate the effects of glyphosate on the composition and diversity of rhizosphere bacterial communities of transgenic soybean. This was especially relevant, because foliar applied glyphosate is transported down to the roots and exuded into the rhizosphere. After two foliar herbicide applications, root samples of treated and untreated plants were analysed by 16S rRNA gene T-RFLP analysis. Multivariate statistical analysis of the data and diversity indices were used to assess changes in the microbial populations in response to glyphosate applications. A comparison of rhizosphere communities revealed that the abundance of a T-RF representing microbes related to Burkholderia sp. significantly decreased under glyphosate application, while the abundance of a T-RF representing uncultured Gemmatimonadetes significantly increased. Interestingly, the bacterial community associated with soybean roots after glyphosate application not only demonstrated effective resilience after the disturbance but in addition, T-RF diversity also increased in comparison to the untreated control samples. The results suggest that bacterial diversity was even stimulated in the rhizosphere after glyphosate application.

Total Nonstructural Carbohydrate Trends in Deeproot Sedge (Cyperus entrerianus)

Native to temperate South America, deeproot sedge has naturalized throughout the southeastern United States. Often forming dense, homogenous stands, deeproot sedge has become widespread, invasive, and potentially harmful ecologically throughout the coastal prairie ecoregion of Texas. Possessing characteristics (rapid growth, generalized habitat requirements) of other weedy congeners (purple nutsedge and yellow nutsedge), its relatively recent expansion highlights the critical need to develop effective control techniques and strategies for this species throughout this endangered ecoregion. Research was performed to delineate total nonstructural carbohydrate (TNC) trends in deeproot sedge rhizomes for development of a phenologically based schedule for herbicide applications and mechanical treatments. Overall, TNC levels were greatest in May to August and lowest from October to January, regardless of study area. Apparently, deeproot sedge exerts little energy into seed production because TNC levels were continually replenished throughout the growing season. As such, foliar-herbicide application throughout the growing season should achieve total plant kill. Conversely, deeproot sedge rhizome TNC levels never fell below 30%, even during winter, which indicates that winter mechanical treatments or winter prescribed fires will not be effective because substantial rhizome reserves are present to support resprouting during the next growing season. Beyond a priori prevention, sequential herbicide applications combined with integrated, sequential, prescribed fire and herbicide treatments will be needed for long-term deeproot sedge control throughout its geographic range.

Comparing Effectiveness and Impacts of Japanese Barberry (Berberis thunbergii) Control Treatments and Herbivory on Plant Communities

AbstractTwo factors that can degrade native plant community composition and structure, and hinder restoration efforts, are invasive species and chronic overbrowsing by ungulates such as white-tailed deer. Beginning in 2007, the effectiveness, costs, and impacts of Japanese barberry control treatments and herbivory on nonnative and native plant communities was examined at eight study areas over 4 to 5 yr. Prescribed burning and mechanical mowing by wood shredder or brush saw were utilized as initial treatments to reduce the aboveground portion of established barberry and were equally effective. Without a follow-up treatment, barberry had recovered to 56 to 81% of pretreatment levels 50 to 62 mo after initial treatment. Follow-up treatments in mid-summer to kill new sprouts included directed heating and foliar herbicide applications. Relative to untreated controls, follow-up treatments lowered barberry cover 50 to 62 mo after initial treatment by at least 72%. Although all follow-up treatments were equally effective, the labor cost of directed heating was four times higher than for herbicide applications. Follow-up treatment type (directed heating vs. herbicide) had minimal impact on species other than barberry. White-tailed deer herbivory had a larger impact on other species than did barberry control treatments. Native grass and fern cover was higher outside of exclosures. Areas inside exclosures had higher cover of Oriental bittersweet and multiflora rose, but not Japanese barberry. Thus, recovery of native communities will require more than simply removing the dominant invasive species where deer densities are high. Excellent reduction of Japanese barberry cover can be achieved using either directed heating or herbicides as follow-up treatments in a two-step process, but other invasive plants may become a problem when barberry is removed if deer populations are low.

Herbaceous Plants and Grasses in a Mountain Longleaf Pine Forest Undergoing Restoration: A Survey and Comparative Study

The Berry College Longleaf Pine Management Area consists of old-growth fire-suppressed mountain Pinus palustris (Longleaf Pine) stands embedded within an encroaching matrix of mixed pines and hardwoods. Since 2001, portions of this area have been subjected to restoration efforts involving logging followed by burning, foliar herbicide application, and planting, as well as burning and hardwood control using herbicides in unlogged old-growth stands. To document the herbaceous plants and grasses of this site and to begin to address questions concerning the short-term impacts of management practices on these species, flowering specimens were systematically collected in managed and unmanaged stands in 2008 and 2009. We recorded 201 species in 35 families, including 70 species of Asteraceae, 35 species of Poaceae, 17 species of Fabaceae, and 10 grass-like species other than Poaceae (Cyperaceae, Iridaceae, and Juncaceae). Native herbaceous plants most commonly found included: Houstonia caerulea, Hypoxis hirsuta, Solidago odora, Oxalis stricta, Coreopsis major, Hypericum hypericoides, Lespedeza procumbens, Hieracium venosum, and Packera paupercula. While only 14 species were found in unmanaged old growth, 127 were found in managed old growth, and 167 in logged areas. Fire suppressed old-growth mountain Longleaf Pine forests are generally virtually devoid of understory plant diversity; these results suggest that reduction in canopy density and leaf litter can substantially recover herbaceous and grass species diversity. However, the extent to which understory diversity can be fully recovered in any specific site remains in question, particularly if local propagule sources have vanished during the period of fire suppression. A comparison with historical species lists at our site, and with other mountain Longleaf Pine forests in various stages of fire maintenance, is presented to help define characteristic understory species for mountain Longleaf Pine forests.

Algerian Ivy Removal Techniques along a Riparian Zone in Berkeley, California

Algerian ivy is an invasive non-native vine that limits native plant biodiversity. In this study I examined three removal techniques for managing Algerian ivy: manual removal, foliar herbicide application (round up® Pro), and cut-stem herbicide application. I hypothesized that cut-stem herbicide application would be the most effective removal technique and that both herbicide applications would not affect native seedling growth. I measured plots monthly for ivy and native seedling growth and analyzed results using a random complete block design, tukey-Kramer analysis, and Simpson’s diversity Index (SdI). I found no significant difference in ivy re-growth among treatments and no significant difference in native seedling growth between plots. However, manual removal plots had an SdI double that of other treatments (0.7652). Based on these results, I recommend that further use of herbicides be ceased until investigations into the effects of herbicide on native plant diversity have been completed.

Biology and Control of Tall Ironweed (Vernonia altissima)

Tall ironweed (Vernonia altissimaNutt.) is a perennial with underground, axillary vegetative buds from which new shoots are produced. In a 2-yr study, tall ironweed plants averaged 6115 seeds/plant. Germination of buried seeds increased with increased time of burial. Foliar herbicide applications were evaluated for control of tall ironweed plants in the pre- to early-bud stages of growth. The triethylamine salt or ethylene glycol butyl ether ester of triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid} was the most effective, providing 93 to 90% control of top growth and regrowth of tall ironweed. The butoxyethanol and propylene glycol butyl ether esters of 2,4-D [(2,4-dichlorophenoxy) acetic acid] alone and in combination with the amine salt of triclopyr also provided excellent control.

Susceptibility of Selected Woody Plants to Pelleted Picloram

Susceptibility of Selected Woody Plants to Pelleted Picloram