Novel Encapsulated Herbicide Delivery Mechanism: Its Efficacy in Mimosa Bush (Vachellia farnesiana) Control

Mimosa bush (Vachellia farnesiana) is an invasive woody weed widely distributed in Australia. While it can be controlled using several mechanical and chemical techniques, this study evaluated a novel herbicide delivery mechanism that minimizes the risk of spray drift and potential non-target damage. This method, developed by Bioherbicides Australia, involves the implantation of encapsulated granular herbicides into the stem of intact plants or into the stump after cutting off plants close to ground level (cut stumps). Trials were implemented near Moree (New South Wales, Australia) on intact (two experimental runs) plants and cut stumped (two experimental runs) plants. For each trial, an untreated control plus the conventional basal bark application of a liquid formulation of triclopyr + picloram mixed with diesel was included for comparison. Encapsulated glyphosate, aminopyralid + metsulfuron-methyl, hexazinone and clopyralid were also tested in all trials. In addition, encapsulated triclopyr + picloram, and metsulfuron-methyl were included in one of the intact plant trials. Aminopyralid + metsulfuron-methyl was consistently most effective on cut stump and intact plants, whilst clopyralid provided highest mortality when applied to cut stumps and single-stemmed intact plants. Particularly for multi-stemmed intact plants, clopyralid should be applied to each stem. Overall, the highest efficacy was achieved on single stemmed plants, but with further refinement of the technique, it should be possible to achieve similar results for multi-stemmed individuals. This method resulted in a reduction in the use of herbicide and environmental contamination while significantly improving speed of treatment.

Output Variation of Trigger Pump Sprayers used for Individual Plant Treatments

Individual plant treatment (IPT) techniques (e.g., basal bark, cut stump, hack and squirt) are used for woody invasive plant management and often rely on small trigger pump spray bottles as an economical and efficient way to deliver an herbicide to the target species. Worldwide, plastic suppliers produce many models and designs with a wide range of uses including pesticide application. However, spray bottle performance has rarely been examined in relation to IPT techniques for operational invasive plant management. We tested ten commonly available spray bottles for trigger output and variation over repeated strokes. We also examined sustained trigger sprayer performance over a six-week period for spray bottles containing water or basal oil carriers, blended with amine and ester formulations of triclopyr, respectively. In the first study, we found significant differences in spray output per stroke between almost every bottle tested. Almost all spray bottle brands yielded outputs greater than 1.0 ml per stroke which exceeds the maximum application amount specified for hack and squirt. Several bottles produced an output of greater than 2.5 ml per stroke. In the second study, the output per stroke was reduced for basal oil mixes, with significant reductions measured for two brands by 21 days and for all three brands tested by 42 days after mixing. These results indicate that consumer-grade trigger sprayers are likely to depreciate rapidly with routine operational use without proper hygiene maintenance. Even then it is likely that these application devices may need to be replaced several times annually. Trigger pump spray bottles are an economical and practical solution for remote field operation and volunteer weed control activities. These sprayers are most suitable for spray-to-wet techniques such as basal bark and cut surface treatments but may potentially be less suited for hack and squirt application which often requires sub-ml precision.

Herbicide Options to Control Naturalised Infestations of Cereus uruguayanus in Rangeland Environments of Australia

While there are many high profile Opuntioid cactus species invading rangeland environments in Australia, Cereus uruguayanus Ritt. ex Kiesl. has also naturalised and formed large and dense infestations at several locations. With no herbicides registered for control of C. uruguayanus in Australia, the primary aim of this study was to identify effective herbicides to control it using a range of techniques. This involved a large screening trial of twelve herbicides and four techniques, followed by a rate refinement trial for cut stump applications and another to test residual herbicides. Despite most treatments (except monosodium methylarsonate (MSMA)) taking a long time to kill plants, at least one effective herbicide was identified for basal bark (triclopyr/picloram), cut stump (aminopyralid/metsulfuron-methyl, glyphosate, metsulfuron-methyl, triclopyr/picloram, triclopyr/picloram/aminopyralid), stem injection (glyphosate, MSMA, triclopyr/picloram/aminopyralid) and foliar applications (aminopyralid/metsulfuron-methyl, MSMA, triclopyr, triclopyr/picloram/aminopyralid) due to their ability to kill both small and large plants. Ground application of residual herbicides was less conclusive with neither hexazinone nor tebuthiuron causing adequate mortality at the rates applied. This study has identified effective herbicides for the control of C. uruguayanus using several techniques, but further research is needed to refine herbicide rates and develop integrated management strategies for a range of situations and infestation sizes and densities.

Efficacy of five herbicide treatments for control of Pyrus calleryana

Callery pear (Pyrus calleryana Decne.) is rapidly spreading in the United States, gaining attention in the last two decades as a serious invasive pest. Recommended control methods include foliar, basal bark, cut stump, and hack-and-squirt application of herbicides, but there are few published studies with replicated data on efficacy. Four readily available herbicidal active ingredients and a combination of two active ingredients were tested for control efficacy against P. calleryana in old-field areas and loblolly pine (Pinus taeda L.) understory. Basal bark applications (triclopyr, triclopyr + aminopyralid), foliar applications (glyphosate, imazapyr), and a soil application (hexazinone) effectively killed P. calleryana with the exception of hexazinone at one site, where rainfall may not have been optimal. Foliar application of glyphosate provided the most consistent control. Our results demonstrate efficacy of registered herbicide formulations for P. calleryana control in two geographic locations and two habitat types. The need for development of integrated pest management programs for P. calleryana is discussed.

Black cherry (Prunus serotina Ehrh.) colonization by macrofungi in the fourth season of its decline due to different control measures in the Kampinos national Park

The experiment conducted in the Kampinos National Park since 2015 was aimed at assessing the sprouting ability of black cherry (Prunus serotina Ehrh.) in response to different measures of mechanical control and mycobiota colonizing the dying trees. Basal cut-stump, cutting at ca. 1 m above the ground and girdling were performed on 4 terms, two plots and applied to 25 trees, 600 trees in total. Sprouts were removed every 8 weeks since the initial treatment for 4 consecutive growing seasons, except winter-treated trees. At the end of the fourth season of control, 515 out of 600 trees were dead (86%): 81% on Lipków and 90% on Sieraków plot. Among 18 experiment variants with sprouts removal, 17 showed more than 80% of dead trees. The lowest, 76% share, concerned summer cut-stump at the base of the tree. For winter measures, the share of dead trees was lower in all cases and ranged from 28% to 64% proving that sprouts removal contributes to the drop of sprouting strength and quicker dying of the trees. Almost 80% of trees showed sporocarps that represented 51 taxa of macrofungi in total, including 6 Ascomycota and 45 Basidiomycota. The group of six most frequently encountered fungi includes: Hyphoderma setigerum, Bjerkandera adusta, Peniophora cinerea, Armillaria ostoyae, Nectria cinnabarina, Stereum hirsutum. Both plots had similar share of black cherry individuals with sporocarps of macrofungi, that is, 81% and 78% for Sieraków and Lipków respectively. The share of colonized trees and the number of reported macrofungal taxa increased significantly compared to the year following the treatment. In addition, the composition of macrofungi changed with the progressing dying of trees. These results broaden the knowledge about macroscopic fungi colonising and living on black cherry within its secondary range of distribution. Moreover, one macrofungus and two microfungi new for KNP are reported.

Integrating conventional management methods with biological control for enhanced Tamarix management

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.

Professional Applicator's Guide to Herbicides for Melaleuca Control

Herbicides are used for integrated management of melaleuca (Melaleuca quinquenervia) trees to kill existing trees. Products with the herbicide active ingredients glyphosate, imazapyr, triclopyr, and hexazinone are used depending on the application method and other factors, including presence of non-target vegetation in the application area. Four application methods, foliar, frill-and-girdle, cut stump, and basal (applied to the soil) are used depending on extent of the population and other factors. Helicopter, truck, or all terrain vehicle (atv)-mounted sprayers, backpack sprayers, and hand-held spray bottles, and dropper bottles are used for application of herbicide. Various adjuvants may be added to the spray mixture to aid or modify the action of the herbicide or the physical characteristics of the mixture. A marker dye is often added to the spray solution to help visualize where herbicide is applied. This document is SS-AGR-258, one of a series of the Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date October 2005.

The dynamics of sprouts generation and colonization by macrofungi of black cherry Prunus serotina Ehrh. eliminated mechanically in the Kampinos National Park

The experiment conducted in the Kampinos National Park since 2015 is aimed at investigating the relationship between the dynamics of black cherry sprouting response and the type and term of implementation of the mechanical elimination procedure. It also identifies macrofungi colonizing trees undergoing eradication. Three treatments, basal cut-stump, cutting (height: ca. 1 m) and girdling, were performed on 4 terms: early and late spring, summer and winter. Each variant was conducted within two plots, and applied to 25 trees, to 600 trees in total. For two consecutive vegetation seasons, sprouts were removed approximately every 8 weeks with the exception of winter-treated trees. Qualitative data were analysed, that is, the number of trees with and without sprouts at subsequent controls, and at the end of the second season, except winter-treated trees. Initially, almost 100% of the trees cut at the base and cut high responded by sprouting. The share of trees without sprouts gradually increased during the following vegetation season, from 3rd to 5th repetition of the sprouts removal, depending on the variant of experiment. Girdling contributed to a delay in sprouting. The effectiveness of procedures, expressed as share of trees without sprouts at the end of the second vegetation season, ranged widely (12%–84%), and depended statistically significantly on the date of the treatment. The effectiveness was higher for treatments done in early (average 68%) and late spring (average 74%), as compared to those done in summer (average 35%). Mycological research concerned 600 trees, including those treated in winter, without sprouts removal. Occurrence of 26 taxa of macrofungi was confirmed on 25% of trees; most of them having wood-decaying properties. Chondrostereum purpureum was most frequent, colonizing 9% of trees. Impact of plots varying soil moisture on succession and rate of fungi colonization, and on sprouting response dynamics requires further research.

The Influence of Treatment Timing and Shrub Size on Chinese Privet (Ligustrum sinense) Control with Cut Stump Herbicide Treatments in the Southeastern United States

Since its introduction to the United States in 1852, Chinese privet (Ligustrum sinenseLour.) has spread throughout the Southeast, invading many natural areas. Manual control by cutting or shredding is one of the most common strategies many land managers employ. However, rapid sprouting from the root collar and lateral roots commonly results in poor control. Cutting followed by either glyphosate or triclopyr application to the stumps is generally effective, but the efficacy of these herbicides in relation to treatment timing andL. sinenseroot collar diameter has not been evaluated. The objective of this experiment was to determine the effectiveness of glyphosate and triclopyr cut stump treatments compared with cutting alone at spring and fall timings across a range ofL. sinensesize classes. Studies were conducted at two locations in Auburn, AL. Treatments included cut stump+no herbicide, cut stump+ glyphosate (120 g L−1), or cut stump+triclopyr (90 g L−1). Treatments were applied to at least 50 experimental units each at April and November timings. Root collar diameter was recorded for each stem, stems were cut 2.5 cm above the ground, and herbicide treatments were applied within 30 s.Ligustrum sinensemortality and sprouting were quantified 6, 12, and 18 mo after treatment. Both glyphosate and triclopyr amine were very effective in controllingL. sinenseat both spring and fall timings. However, glyphosate provided slightly better results than triclopyr when lateral sprouting was included. Application timing also was significant, with a lower percentage of sprouting following November treatments than April treatments. Stem size influenced treatment success, as larger stumps tended to sprout more than smaller stumps. These results indicateL. sinensecan be controlled with cut stump herbicide treatment using either glyphosate or triclopyr with spring or fall timings at concentrations much lower than typically used.