Taking the time to care for plants or visiting your local park helps to relieve some stress of the COVID-19 pandemic, says Angela Moles, plant ecology professor at University of New South Wales (UNSW).
“My garden at home attracts the local wildlife, so when rainbow lorikeets come to visit for the nectar from the native flowers, our kids love going outside to watch them — just one of the many benefits of having a good garden,” she says. “I also spruced up a shared patch of grass in my community with lots of plants — my neighbors stopped to talk to me, shared gardening tips and said, ‘Wow, well done, that looks so much better.’”
Philippa Specker, a PhD and Master of Psychology candidate at UNSW says taking the time to care for plants can be used as a self-soothing or distraction technique to help people cope with negative emotions like fear, sadness and anger.
The South Korean government is even paying attention to how plants improve mental health. According to NBC News, South Korean officials distributed 2,000 “pet plant kits” to people living in self-quarantine to help them battle depression and other mental health conditions brought on, or exacerbated, by the pandemic. The government handed out Sanhosu (coralwood in English), which is associated with bravery, Lee Yong Kwon, director of the forest education and healing division at the Korea Forest Service, told NBC. Lee says a plant can “ease the loneliness often felt by people in isolation by providing companionship and bonding ...”
Furry friends
Photo s by Kelli Rodda
I ordered more houseplants during quarantine and added more shrubs and perennials to my landscape during the lockdown. I’ve always agreed that gardening is therapeutic. But it was the unconditional love of my dogs and the aloof love of my cat (Roxie, Radar and Felix are pictured below) that helped my mental state the most these last few months. (Sorry, honey. You’re a wonderful husband, but pets are just better at keeping depression at bay.)
The American Heart Association (AHA) says pets can help mental health because they lower work-related stress. Working from home allowed us to spend working hours with our pets. Pets can also help increase productivity and help manage anxiety.
Whether it’s a haworthia, an azalea, a Labrador or a tabby, plants and pets help quell feelings of isolation. Keep that message flowing to consumers, even after the pandemic subsides.
My hope is that you had something or someone to help you cope this year.
Dichotomously branched vegetative thallus structure of liverwort (Marchantia polymorpha). The gemma cups are asexual reproductive structures which contain numerous gemmae. The gemmae spread with irrigation water splashing and germinate in suitable conditions to produce an entire new liverwort plant.
Photos by Debalina Saha, MSU Horticulture
Liverwort
Liverwort is primarily a problem in herbaceous perennials, woody ornamentals or crops with long production cycles with a dormant or vernalization period where crops remain damp for long periods of time. There are thousands of liverwort species with Marchantia polymorpha being the most common one prevailing in greenhouses and nurseries, according to Marble et al., 2017.
Liverwort, including M. polymorpha, prefer cool temperatures, low ultraviolet (UV) light radiation, high fertility and moist or damp substrate. It reproduces rapidly in the presence of overhead irrigation, poorly drained or moist areas. The optimum temperature for vegetative growth is 64-72 °F. These environmental conditions are common inside greenhouses and nurseries, and the organism thrives and spreads rapidly once established in containers.
Liverworts form dense, prostrate mats covering the soil or container media surface. In container production, liverwort becomes highly competitive with the ornamental crop for water, nutrients and space. The liverwort mat can prevent the irrigation water and fertigation from reaching the root zone of the ornamental crop and can repel water when dry. As a result, the overall quality and market value of the ornamental crop decreases.
M. polymorpha is a non-vascular plant and has a thallus structure. It can reproduce through both asexual as well as sexual reproductive cycles. In gametophytic life cycle, the liverwort propagates asexually by producing gemmae within the gemma cups. Each gemma cup can produce numerous gemmae (asexual plant buds). Gemmae are released to the immediate area when splashed by water from rain or irrigation. After leaving the mother plant, each gemma can form one to two clonal plants after contact with moist soil or substrate.
Liverwort growing profusely in containers along with ornamental plants inside a greenhouse.
At temperatures of 50-59 °F, M. polymorpha develops sexual structures. Stalked, umbrella-like male and female reproductive structures are borne on separate thalli. Sperm cells produced by the antheridia travel via water (rainwater or irrigation splashing on the upper surface of the antheridiophore) to fertilize the eggs on the undersides of the archegoniophore, according to Marble et al., 2017. After fertilization, spore development takes place. Once they mature, they get dispersed by wind or water and germinate on moist substrate under suitable growing conditions.
Managing liverwort in container production can be challenging. For a successful liverwort control, it may require a combination of herbicide applications along with proper cultural and sanitation practices. There are very few herbicides labeled for greenhouses, as there can be phytotoxic effects on the ornamentals.
Even the best herbicides will not provide effective weed control if they are not applied accurately and uniformly. Too little product results in poor weed control and higher hand-weeding costs. Too much can injure crops, reducing the number available for sale. Most granular herbicide labels contain some recommended settings for common application equipment. However, these recommendations are just starting points. To obtain the correct dose, you need to calibrate the spreader. Spreader calibration is essentially a very simple process:
Measure the width of spread;
Apply the granules to a small area;
Measure the amount applied to this area;
Compare this amount to the desired dose and adjust the spreader settings until the desired output is obtained.
Maintaining a consistent speed
Both your walking speed and the speed at which you turn the spreader handle will influence the rate at which the product is applied. A consistent speed will help maintain a uniform application rate and distribution.
For walking speed, measure a distance of 100 feet in an area that is similar to the location where you will be applying the granules.
Using a stopwatch, determine how long it takes to walk 100 feet. Most spreader manufacturers recommend walking about 2 to 3 mph. At 3 mph it takes about 23 seconds to walk 100 feet. A 2-mph pace requires about 34 seconds per 100 feet. Use a portable metronome or smart phone app to help keep a consistent walking speed. Experiment with a few different settings until you find one that allows you to walk at the desired pace. To achieve a 3-mph pace, a good starting point is between 99 and 103 beats per minute. But this number will be different for different applicators.
For handle cranking speed, turn the spreader crank at a consistent speed that is easy to maintain, generally one rotation per second.
You can practice with the metronome set to 60 beats per minute until you can walk with a consistent pace.
Spreader calibration step 1
The first step is determining the effective swath width and distribution pattern.
Granular spreaders do not distribute the same amount of material across the width of the treated area. More granules are deposited directly in front of the applicator than at the edges and the applicator will have to overlap each pass when applying herbicides. Therefore, you need to determine the effective swath width. The effective swath width will be narrower than the entire width of spreader throw.
Supplies needed:
Granular spreader
Herbicide of choice
7 to 9 containers such as catch bins, trays, or 1-gallon (3 or 4L) nursery pots lines with plastic bags
Measuring tape
A small scale (able to measure 1 gram)
Metronome (battery operated or smart phone app)
Stopwatch
Numbered bags/jars to hold herbicide granules
Personal protective equipment
Steps
Set out the catch pans or bins 2 feet apart on center, perpendicular to the direction you will be walking (Figure 1). Place the pans on a flat, dry, and empty nursery bed covered with landscaping fabric or plastic.
Mark a starting point about 20 feet in front of the center box. Mark a point along your walking path to open the hopper (at least 12 feet in front of the center box).
Practice walking toward the boxes at a consistent pace, using a steady handle cranking speed and stepping over the center box (use the metronome).
Fill the spreader at least 1/2 full.
Use the center rudder position (or just right of center).
Adjust the spreader to the herbicide manufacturer’s recommended output setting and spread granules while walking toward and over the boxes. Open the hopper at least 12 feet in front of the center bin and always walk toward the bins from the same direction. Keep the hopper open until just past the catch bins. Repeat the process at least two more times. When spreading, start turning the handle before you open the hopper and continue turning the handle after closing the hopper until no more granules spread out. This helps reduce spreader jamming.
Weigh the granules collected in each bin.
Measure the weight of granules collected in the center bin. Divide this number by two and find the collection bins on either side of center that have about half as much product as the center bin. The distance between the two bins is the effective swath width (Example A).
To determine the distribution pattern (Example B), use a piece of graph paper to chart the amount of granules in each bin and draw a line through the center (Figure 2). If the pattern is lopsided, plan to spread granules in one direction or make two passes in opposite directions over the same path.
If the test site was dry, you can sweep up the granules and reuse them.
Adobe Stock
Example A: Determining the effective swath width
In this example, the weight of the herbicide collected in each bin is recorded in the chart below.
2.4 grams were collected in the center bin. Half that amount would be 1.2 grams.
The bin 4 feet to the right of center contained this amount.
On the left side, the area to receive 1.2 grams of material would be about halfway between the bins 2 and 4 feet left of center.
Thus, we would conclude that the effective swath width would be from about 3 feet left of center to 4 feet right of center, or 7 feet wide. This is the width used in
Example B: Determining distribution pattern
Graph the amount of granules in each bin (Figure 2). This particular distribution pattern is balanced with similar amounts spread to the left and right. However, depending upon the granule, the spreader, and the dose applied, the amount spread to the right may be greater than the amount applied to the left.
Alternative swath width method
If you don’t have a scale, use this technique developed by NC State University pesticide education specialist Dr. Wayne Buhler. Use a clear seven-day pill organizer to visually estimate swath width. Caution: clearly label the box as having been used with pesticides and keep the box in the pesticide storage facility.
Label each compartment with the number of feet from the center. Keep left and right of center orientation clearly marked.
After collecting granules as described in steps 1 through 6, use a funnel to put the contents of each collection bin into the corresponding sections of the pill box.
Locate the compartments with about 1/2 as much product in them as the center compartment. This allows you to find your swath width and basic distribution pattern.
Spreader calibration step 2
The second step is determining the application rate.
Fill the hopper on the spreader at least 3/4 full of product.
Weigh the filled spreader and record the weight.
Operate the spreader over a known distance (at least 25 feet).
Reweigh the spreader and subtract the current weight from the original weight to determine how much product was used.
Calculate the area covered (distance the granules were spread multiplied by the swath width of the spreader).
Calculate the dose (weight of granules used divided by the square feet of area covered).
Adjust the spreader output setting or your walking speed until your application dose is within 10% of the labeled (or target) dose.
Example C: Determining the Dose
Assumptions:
Labeled (target) herbicide dose: 150 pounds/acre
Effective swath width: 7 feet
Length of walking area: 30 feet
Area = 210 square feet (swath width x length of area treated)
Beginning weight of spreader with herbicide granules: 195 ounces (oz)
Ending weight of spreader with herbicide granules: 186 oz
Difference: 9 oz applied
Convert ounces to pounds: 9 oz ÷ 16 oz per lb = 0.56 lb applied
Calculate the dose:
Divide the amount applied by the area to obtain the amount per sq ft:0.56 lb ÷ 210 sq ft = 0.0027 lb/sq ft
Multiply by 43,560 (number of sq ft per acre) to obtain the dose in lb/A. 0.0027 lb/sq ft x 43,560 sq ft/ acre = 118 lb/A
This dose is more than 10% below the target dose of 150 lb/A. Adjust the spreader settings (or walking speed) to allow slightly more output and repeat the process until the rate falls within the acceptable range (135 to 165 lb/A).
You will need to follow this calibration procedure for each herbicide.
Dr. Joe Neal is a professor of weed science, extension specialist and department extension leader at North Carolina State University, https://weeds.ces.ncsu.edu/
Successful weed cessation
Supplement - State of the Market: Weed Control Report
Add Marengo® to your weed management toolbox for long-term control.
An effective weed management program includes a variety of tools and tasks, such as sanitation, cultivation and barriers, and the application of herbicides. Although weed management requires labor hours, the proper use of preemergence herbicides will help alleviate time spent weeding, allowing crews to perform other tasks.
Marengo®, a preemergence herbicide available in granular and liquid form, has the potential to provide up to eight months of weed control. Marengo is labeled for use on 270 plants with applications timed in fall or spring for enhanced flexibility. It is also labeled for use inside greenhouses and can be applied for weed control on floors and beneath benches. It’s available in two formulations — as an 18-ounce and 64-ounce liquid soluble concentrate or as a 50-pound granular with Verge® carrier technology.
Marengo’s active ingredient, indaziflam, has a unique mode of action that inhibits root development during weed germination by blocking cellulose biosynthesis.
“Marengo is the only active ingredient in the Weed Science Society of America (WSSA) Group 29, making it an effective rotational product in IPM programs,” says Dr. Aaron Palmateer, senior technical support with Bayer’s Ornamental business segment.
Dr. Palmateer suggests that for best results, growers should apply in fall for continuous weed control into the following growing season. He also recommends irrigation within 21 days of application.
Growers can apply Marengo using directed spray around ornamentals or broadcast in non-crop settings to prevent broadleaf weeds, grasses and annual sedges from seed. For spot treatments, the equivalent rate is 0.17-0.36 fluid ounces per 1,000 square feet.
Trials
Hannah Mathers, owner of Mathers Environmental Science Services and former professor and state extension specialist at The Ohio State University, trialed Marengo with spray applications on a variety of dormant (prior to bud break) field-grown boxwood and Taxus at three different sites.
“We found it performs really well as a dormant application. When applied in December, growers could easily get 21 weeks of control from Marengo when applied at the 15-ounce rate,” she says. “That takes growers into May and hopefully growers are almost done with shipping by that point and can go in with another application of a different product — something a little bit lighter — in June.”
In her trials, it worked well on winter annual weeds that come up in early spring such as mustard and bittercress. Some of the more difficult weeds such as Canada thistle will likely need spot sprays to knock them down.
Mathers says dormant applications provide the ability to use nursery staff in winter (which is traditionally a “down-time” labor-wise versus spring). Dormant applications also provide insurance that applications will be completed before weed germination, versus waiting for spring when other production tasks often take precedence.
“These dormant applications also seem to be key in providing the ‘power’ and ‘duration’ of efficacy necessary to clean up nursery fields,” she adds.
Mathers also trialed a fall granular application of Marengo on dormant daylilies, with efficacy that lasted well into the growing season.
“In the perennial trial, we noticed the efficacy doesn’t change that much with the 200-, 400- or 800-pound rate. We also did an application around June/July on the daylilies, but there was some phytotoxicity, most likely on plants that were already weak. But they did fine with the fall application,” she explains.
Marcelo Moretti, assistant professor at Oregon State University’s Department of Horticulture, trialed Marengo in container-grown crops. He found that it performed well on annual grasses (crabgrass, foxtails, annual bluegrass) annual broadleaves like oxalis, bittercress, spurge and willowherb.
He also found that it controls liverwort. “Not many chemicals do that,” he says.
Although Marengo is a preemergence herbicide, Moretti found that it has some postemergence activity, as well.
“I observed excellent control of willowherb with Marengo applied in post-emergence and suppression of black nightshade. Just to be clear, Marengo really shines as a preemergence herbicide, which is how it should be positioned in a [weed management] program. [But] the little postemergence comes as a bonus,” he explains.
In his trials, Moretti was also screening for crop tolerance and efficacy.
“For crop safety, I noticed that conifers in general are very tolerant to Marengo that is applied over the top. Same with boxwood, roses and other species,” he says. “The exception to that is hydrangea, and this year we noticed that Ilex x meserveae ‘Blue girl’ was sensitive to Marengo. The key is to do a small test whenever trying Marengo on a new crop, but that is true of all herbicides.”
The newly revised Marengo label allows for testing.
“If a desired plant is not listed, treat several plants at the maximum use rate and evaluate one to two months later for acceptable tolerance. The user assumes responsibility for application to plants not listed on this label,” Palmateer explains.
The cost-effective solution
Properly applying preemergence herbicides helps reduce labor costs related to weed management. When evaluating different preemergence solutions, it is important to look at the total program cost, which is best measured as cost per acre per month of control.
This includes:
cost of product and labor for the initial application
cost of product and labor for clean-up
cost of product and labor for any reapplication treatments.
Products that are less expensive upfront but have a short residual will require more frequent reapplication and/or more clean-up between applications. This increases both labor and product costs. Products offering longer residual control, such as Marengo, will reduce the frequency for reapplication and clean-up applications because they last longer, reducing labor and product cost. No product lasts longer than Marengo, making it one of the most economical program options for weed management based on cost per month per acre of control.
A product that lasts up to 4 months will have to be applied twice to achieve similar results to a product that lasts up to 8 months. That means the labor cost will be twice as expensive for the shorter-lived product. Every herbicide application includes labor for: site preparation; application prep (equipment, handling, mixing, etc.); application; and clean up (equipment, disposal, etc.).
Bayer offers an easy way to track your herbicide costs with its Cost-in-Use Calculator. Users can compare any herbicides and retrieve cost analysis to maximize your investment. Plug in information that fits your exact parameters and see side-by-side numbers for any herbicides you choose.
Make a plan. Once the nursery is planted, it becomes more diffcult to control weeds.
Photos by Kelli Rodda
Weeds are a continuous issue for nursery production crews since they can pop up in any area of the operation throughout the year. To win the war on weeds, nurseries should adopt best management practices (BMPs) to save labor, inputs and improve overall plant health. The University of Massachusetts Extension has provided these strategies for an improved weed management system.
Scouting
All areas of the nursery (nursery fields, container yards, hoop houses, greenhouses, potting and propagation areas, holding areas and areas adjacent to these locations) should be scouted for the presence of weeds on a regular basis. Give special attention to those weeds that might be new to a nursery. Correctly identify and record all weeds. Determine and record the life cycle of each weed. Regular scouting enables a nursery manager to plan and implement appropriate management strategies and evaluate the long-term effectiveness of those strategies.
Planning
Develop a weed management program before planting. This should be one of the first steps in the production process. A complete weed management program outlines all strategies to be implemented.
Preventive strategies
Weeds should be prevented from going to seed in all areas of the nursery. Control measures include mowing, hand-pulling and herbicides. Weeds should be controlled before they produce viable seed. Special attention should be given to weeds with unique seed dispersal mechanisms. Seeds can be moved by wind (dandelion, horseweed, groundsel, hawksbeard), splashing irrigation water (chickweed, pealwort) and force seedpod dehiscence (woodsorrel, bittercress). Optimize the production cycle and minimize the duration in which container and field nursery stock remains in the nursery. Weed problems increase over time and nursery stock that is held for long periods of time can be problematic. In nursery fields, a short production cycle allows for effective perennial weed control. Control weeds in nursery fields before planting. This is especially true for difficult-to-control perennial weeds such as mugwort, quackgrass, yellow toadflax, bindweed and Canada thistle. Once the nursery is planted, it becomes increasingly difficult to control these weeds.
Pre-plant applications of a non-selective, translocated herbicide will effectively control many perennial weed species. Cultivation, unless it is done multiple times over a period of time, may spread perennial weeds. Cultivation also can result in the loss of soil structure and organic matter. If weed populations are considerably different among nursery fields, cultivation equipment should be washed to remove soil and weed seeds. Maintain a weed-free ground cover in field nurseries.
Depending on the type of nursery stock being grown, fields can be maintained either vegetation-free or in a system in which the weed-free areas are maintained in the rows and a persistent sod grassway is established and maintained in the alleys. Weed control in the rows can be achieved with programs that include residual preemergence herbicides and both selective and non-selective postemergence herbicides. These areas can also be mulched. If cultivation is used to control weeds in the row, pay special attention to the movement of soil. Over time, a substantial ridge of soil may develop at the base of nursery stock and be detrimental. Sod grassways will support equipment and allow field access for digging, spraying, mowing and other practices to continue when soils are muddy and snow covered. Additionally, sod grassways can effectively compete with weeds and prevent their spread. These areas are traditionally managed by mowing; however, plant growth regulators can also be used. Maintain a weed-free area around the base of nursery stock. Nursery stock that is surrounded by weeds is prone to rodent damage. Weeds around the base of nursery stock can compete for water and nutrients. Maintain cover crops in fields that are not being used. Cover crops will not only improve soil but also reduce weed growth. Winter rye and oats can be used as cool-season cover crops. Buckwheat and sudangrass can be used as cover crops for the summer months. Maintain weed-free areas around and between greenhouses and hoop houses. These areas can be a source of weed seed that can infest container nursery stock. An early season preemergence herbicide or a postemergence non-selective and preemergence herbicide tank-mix can be used.
All weeds should be controlled in container areas. Nursery fabrics can be used in container areas to prevent weed growth. Container media that has spilled or has fallen from nursery container drain holes and all plant debris should be cleaned from container areas. While initially weed-free, growing media that is stored improperly or in an open area can quickly become contaminated with weed seeds. Covering the pile or storage indoors should be considered as strategies to keep weed seeds from entering the media. If soil or compost is a component of a container media the weed levels should be determined. Nursery liners and transplants should be weed-free. Inspect purchased liners and transplants for weed growth. If weeds are present, remove as many as possible, especially those near the surface, before planting. Ask the supplier questions about their production process weed management programs and weed levels before purchase. Nursery containers that are going to be reused should be washed thoroughly. Washing should be done in a manner that removes all leftover growing media and weed seeds. Many weeds are very small and can easily be missed when containers are inspected visually so washing is necessary. Routinely scout and monitor newly potted plants. Recently planted nursery containers can be very prone to weed growth. If weeds do appear, examine the nursery container closely and determine if the weeds are germinating from the liner or from the growing media. Take the appropriate action based on the location of the weeds. Implement management strategies that are targeted toward preventing weed growth in container nursery stock. Several container surface covers can be used to reduce weed growth in nursery containers.
Growers should keep in mind that recently planted containers are prone to weed growth.
Herbicides and applications
All characteristics of a particular herbicide should be considered when selecting an herbicide, including weed species controlled and longevity of effective control, weed growth stage at time of application, crop tolerance to herbicide and potential for injury, herbicide rate and activation requirement including rainfall/irrigation free period, application timing, herbicide formulation, herbicide mode of action, herbicide persistence and speed of degradation, potential for leaching and runoff, potential for injury from spray drift and volatility, selective vs. non-selective, contract vs. systemic/translocated, and cost. The product labels of all herbicide products should be read and understood before application. Make applications according to label directions.
Combine herbicides to increase the spectrum of weeds controlled. Most herbicides used singly do not control all the weeds at a specific site. A particular preemergence herbicide is generally stronger on “grassy weeds” or “broadleaf weeds” and therefore a tank-mix of “grass” and “broadleaf” herbicides will increase the spectrum of weeds controlled. Apply preemergence herbicides at frequent enough intervals to maintain effective weed control. Rotate herbicides based on mode of action and weed spectrum controlled. Using the same herbicide or herbicides with the same mode of action at a specific site can result in a shift in weed populations as well as increase the potential for herbicide resistance. If weeds that had previously been controlled with a specific herbicide are not currently being controlled, herbicide resistant weed populations may be developing. Steps should be taken to prevent suspected weeds from producing seed and spreading.
All herbicide application equipment should be calibrated on a regular basis. Check delivery rate and application pattern on all sprayers and spreaders and adjust accordingly. Replace worn or damaged spray tips. Apply herbicides based on the germination period and growth stage of the specific weeds. Postemergence herbicide applications should be made only to weeds that are actively growing and not under moisture stress. Weeds should not be mowed for two weeks prior to and one to two weeks after application.
An accurate record of all herbicide applications should be kept on file. Information recorded should include application date, herbicide used and formulation, herbicide rate and spray volume output, weeds present and their growth stage, crops and their growth stage, location and amount of area treated, weather (air temperature, dewpoint temperature, wind speed and direction, post application rainfall), soil moisture, application problems, and other information that might be helpful. Avoid over-watering container and field nursery stock. Over-watering can increase weed germination and establishment. The effectiveness of preemergence herbicides can be significantly decreased as a result of herbicide degradation as a result of over-watering. Thoroughly clean herbicide application equipment after application. Evaluate herbicide applications for effectiveness. Use the information collected to make appropriate adjustments to the herbicide program.
Best Management Practices information compiled by Tina Smith and Paul Lopes, University of Massachusetts Extension; weed management information edited by Randall Prostak, University of Massachusetts. Read the entire BMP publication at https://bit.ly/nursery-BMPs
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