A Review of Non-Chemical Weed Control Practices in Christmas Tree Production

Weeds interfere with Christmas tree growth at any time and at any stage of production. Growers mostly rely on mechanical mowing and applications of herbicides for weed control in their fields. However, herbicides can be phytotoxic to non-target plants, can cause environment-related issues, and their repeated application can even cause herbicide-resistant weeds. The main objective of this manuscript is to provide a review of non-chemical weed control strategies in Christmas tree production and identify areas where current practices could potentially be improved or in which further research is required. Preventing the introduction of weed seeds requires controlling weeds along farm roads, maintaining clean equipment, and eliminating new weeds before they start seeding. Mowing helps to reduce the number of seeds produced by the weeds and can significantly reduce competition with trees. Shropshire sheep are well suited for grazing Christmas tree plantations as they prefer grazing on grasses and weeds rather than on coniferous trees. Weeds can also be controlled around Christmas trees by mulching. Organic mulch can improve soil moisture, maintain soil temperatures, enhance root establishment and transplant survival, and improve plant establishment and overall growth. Incorporating cover crops into Christmas tree plantations may improve tree growth, quality, and soil fertility and can supplement conventional nitrogen fertilizers. However, if cover crops are not properly managed, they can be highly competitive with the trees. Flaming can cause suppression of many annual weed species but is less effective on larger weeds and needs to be applied with caution. Several insects have been used as biological agents to control selective weed species. However, further research is required to focus on several potential biological agents, different types and depths of mulches, on cover crops types and their competition with different species of Christmas trees and their effects on seedling survival and growth

Allelopathic Effects of Common Landscape and Nursery Mulch Materials on Weed Control

Use of organic mulch materials such as pinebark, pinestraw, or various hardwood chips for weed control is a common practice in residential and commercial landscapes. Mulch can inhibit weed seed germination and growth through light exclusion, acting as physical barrier, reducing available moisture to weed seeds within the mulch layer, and through release of allelochemicals that may inhibit germination or growth of some weed species. Previous and current research on allelopathic chemicals present in mulch have focused on cover crops and their residues with an emphasis on agronomic crops. These materials would not be suitable in a landscape setting due to rapid decomposition, lack of commercial availability, and little aesthetic appeal. Research is needed concerning identification, quantification, extraction, mechanism of release, persistence, selectivity, genetic regulation, and mode of action of potential allelochemicals present in mulch materials used for landscape purposes. More knowledge of these natural chemicals could aid practitioners and homeowners in the selection of mulch and identify potential new mulch materials that could be utilized in these industries. The purpose of this review is to summarize previous research pertaining to allelopathic compounds present in commonly used mulch materials and identify new potential mulch materials that could be utilized in the landscape sector based upon allelopathic properties. Current areas where additional research is needed are also identified

A Retrospective Study on Pre Exposure Hydroxychloroquine and Ivermectin Prophylaxis for COVID-19 in Healthcare Workers in a Tertiary Care Hospital

Background:COVID-19 was declared a ‘pandemic’ by the WHO on 11th March, 2020. The high infectivity and unique transmission potentials of the causative agent of COVID-19, namely, SARS-CoV-2 were the reasons behind its wide-scale spread and made health care workers (HCWs), the most ‘at-risk population’ for acquiring the infection.The administration of HCQs and/or Ivermectin prophylaxis was one of the most commonly used stratagems recommended to protect the HCWs prior to the development of an effective vaccine. But data on its effectiveness, if any, were not conclusive. Also the above strategy was not accepted by many HCWs themselves for a plethora of reasons. Hence a systematic enquiry into the above conundrums was felt to be the need of the hour. Objective: 1.To assesses the effectiveness of HCQs and Ivermectin as pre-exposure prophylaxis (PrEP) drugs against SARS-CoV-2 infection among HCWs in a tertiary care hospital. 2. To identify the reason(s) behind avoidance of PrEPamong HCWs. Materials and methods: We conducted a retrospective study based on an online/ offline/ telephonic survey on HCWs directly related to COVID care services. Results: Total 336 HCWs responded to our survey. There were segregated intotwo cohort groups, namely, those taking PrEP (n=148; exposed) and those avoidingPrEP (n=188; control). In the PrEPgroup, 26 (17.56%) out of 148 participants reported to have tested positive for SARS-CoV-2 during some point of time, whereas, in the control group, 38 (20.21%) out of 188 participants reported to have been SARS-CoV-2 positive. We found no significant reduction SARS-CoV-2 cases in exposed group with relative risk of 0.8691 (95% Confidence Intervals 0.5542 to 1.363, p <0.3181).Conclusions: Our study demonstrated that voluntary consumption of PrEP by HCWs is not associated with a statistically significant reduction in risk of SARS-CoV-2

Alternative Integrated Weed Management Options for Clopyralid-Resistant Common Ragweed

Common ragweed (Ambrosia artemisiifolia L.) is an extremely competitive broadleaved summer annual weed found in Christmas tree production systems within Michigan. Common ragweed has been reported to have resistance to glyphosate, PSII inhibitors, PPO inhibitors, and ALS herbicides. There have been reports from Michigan Christmas tree growers of common ragweed resistance to clopyralid, a synthetic auxin herbicide, in Montcalm County, Michigan. The objective of this study was to test alternative post-emergence herbicide combinations and organic mulch on clopyralid-resistant common ragweed for weed control efficacy. The following two stages of common ragweed were used: stage 1 (6–9 leaves) and stage 2 (12–14 leaves). For common ragweed in stage 1 in 2021 and 2022, as well as stage 2 in 2022, at all evaluation dates, mulch + clopyralid + oxyfluorfen provided the highest level of weed control. For stage 1 in 2022, this treatment combination provided 100% control from 2 weeks after treatment (WAT) and always showed better or equal weed control compared to all the other treatments. The combination of mulch + clopyralid + glyphosate provided 100% control by 2 WAT when plants were treated at stage 2 in 2022. For the plants treated at stage 1 in 2022, many of the treatments reached a fresh weight of 0 g, but in 2021, those same treatments resulted in a fresh weight of around 20 g. Based on fresh weight, the greatest plant growth occurred with glyphosate treatment in 2021 and clopyralid and mulch alone in 2022. This is likely due to common ragweed’s resistance to these herbicides

A Review of Chemical Weed Control Practices in Christmas Tree Production in the United States

Christmas trees are sensitive to weed competition, especially during establishment. In initial stages of the tree crop, weeds can utilize available soil moisture and trees may succumb to drought stress. In later stages, weeds can even interfere with production practices. Non-chemical weed control methods alone may not provide effective weed control. Chemical weed management strategies involve the use of preemergence and postemergence herbicides at the right timing and application rates. There are many herbicides that are used in Christmas tree production in the United States, and each has specific application guidelines and weed control spectra. Moreover, crop trees vary in tolerance by species and tree age. Growers need to be careful while applying herbicides as many of these chemicals can cause injury to Christmas trees. Repeated application of herbicides with the same mechanism of action has resulted in development of herbicide resistance among several weed species. Managing herbicide resistance has now become an important issue. More research is required on identifying and managing herbicide resistance among weed species in Christmas tree production. Future research needs to focus on herbicide and mulch combinations, herbicide rotations, and tank mixing different herbicides with different mechanisms of actions and how these affect Christmas tree varieties

Decolonizing the Engineering Curriculum

Decolonizing the Engineering Curriculum is a set of adaptable resources developed to enable Engineering faculty to include Indigenous reconciliation in engineering courses. OER Description: This unit plan provides adaptable resources developed to enable Engineering faculty to include Indigenous reconciliation in engineering courses. This open educational resource (OER) contains learning objectives, examples, recorded lessons, and sample lesson plans for faculty to use for their courses. The most recent version of this OER can be found in the Open UBC Pressbooks Catalogue.Applied Science, Faculty ofCivil Engineering, Department ofUnreviewedFacultyResearcherUndergraduat