What to Do About Weeds, With Invasive Plant Activist, Educator Susan Mason

Susan Mason knows her weeds. She knows most of yours, too. She is particularly familiar with the weeds of Bidwell Park after having worked more than 4,000 volunteer hours over the past 12 years helping to identify, map, work toward eradicating, and follow-up monitoring all manner of invasive weeds in the park – one of the largest municipal parks in the country at 3,670 acres. Photo: Susan Mason, armed with a large bag for picking up trash as she walks, near the entrance to the ‘Lost Park’ section of Chico’s Bidwell Park.

On September 24th, Susan will be teaching a class on Controlling Invasive Plants for the Chico State Herbarium. The class is targeted in part at home gardeners and private landowners looking to gain more effective and efficient skills at dealing with weedy plants on their own properties, although 4 hours of DPR continuing education units are available to Pest Control Advisors, Ground Applicators and Private Applicators for taking the class. “Invasive plants taking over your property? Spending too much time weeding your garden?” the class flyer asks, “Learn to identify common local garden, pasture and forest weeds, and develop effective methods to control them. Learn how timing, technique, and specialized tools can be used to reduce your weeding time and why knowing a little about the plant’s biology can improve your chances of successful weed control or eradication.” The fee for the 9 am to 1 pm class is $35, pre-registration is required. A weed walk with CSU, Chico Professor Emeritus of Biological Sciences Wes Dempsey will be offered following the class. For more information or to register, contact (530) 898-5356 or jbraden@csuchico.edu, or go to: http://www.csuchico.edu/biol/Herb/workshops/Invasive_Plants_9-24-11.pdf. Photo: Two of our region’s more pernicious invasive plants: on the left, tree-of-heaven and, on the right, Himalayan blackberry.

In a climate such as the North State, staying on top of invasive plants is a daunting prospect. This year alone, Mason worked with crews of volunteers organized by the non-profit “Friends of Bidwell Park” (FOBP) to remove a final batch of “5,809 Japanese privet trees, saplings, and seedlings” from the area of Bidwell Park between Annie’s Glen and Five Mile recreation area – an area about four miles in length. This was a final sweep after six and a half years and over 3,700 hours of volunteer effort by FOBP, as well as “many additional hours contributed by park staff, Park Division volunteers, California Conservation Corps, and the Salt Creek Conservation Camp” trying to eradicate Japanese privet from this area.

“Japanese privet (Ligustrum japonicum) are an introduced species that has spread rapidly through Bidwell Park since being introduced in Chico. Plant invasions like this reduce the number of native plants by out-competing natives for resources such as water, nutrients and sunlight. Privet is one of 22 plants on the Butte County’s Noxious Weed list. Privet is spread primarily by birds and the plants are found throughout the Chico area, especially along the Highway 99 corridor, where they were planted for screening after its construction.” Bidwell Park has somewhere just under 600 known native plant species, and more than 300 non-native plants, “but only about 130 of these non-natives are known to be weedy or considered invasive by one or more reputable state, federal or plant group. There is no real reason to remove a non-native plant if it is not harming the native plants’ ability to grow and thrive,” asserts Susan. “I have about 30 plants on my high-priority list for removal and monitoring!” she laughs. (I suppose if she didn’t laugh, she would be too overwhelmed to keep functioning.) All of Susan and the Friends of Bidwell Park’s work at invasive plant removal and eradication is determined in collaboration, requested and approved by the City of Chico’s Parks department, whose funding and staffing could not possibly stay on top of these noxious weeds themselves. Photo: A dense stand of Japanese privet saplings growing out of an equally dense patch of English ivy in Bidwell Park. Not difficult to see how these plants literally suffocate out all other plants in their way. PHOTO COURTESY OF SUSAN MASON.

Since moving to the Chico area in 1999, and helping to form Friends of Bidwell Park in 2003, Mason has been a tireless advocate for protecting the native landscapes of the North State from invasive plants. She has served in almost every position on the FOBP’s Board of Directors, as well as served as Invasive Plant Chair for the Mt. Lassen chapter of the California Native Plant Society. In 2005, Susan received the Land Manager of the Year award from the California Invasive Plant Council (Cal-IPC).

“What I have learned from on-going weed workshops and my own experiences in the field,” Susan tells me as we walk through a portion of Bidwell Park known as ‘lost park’, “is the importance of knowing how a specific weed reproduces and spreads before attempting to control it. Often the control timing or method used by gardener actually helps to spread the weed or stimulates it to reproduce. For example, a former neighbor cut down a Brazilian peppertree (Schinus terebinthifolius) and, within a few weeks, its roots had created new sprouts in all directions up 40 feet away from the tree stump. Now he has dozens of plants to eradicate (and the tree stump is sprouting, too).” Likewise, Susan points out to me, many large weedy trees such as tree-of-heaven (Ailanthus altissima) have shallow root systems, and will sprout all along these roots in a survival response when they are seriously disturbed, for instance if they are cut down. In the park, Susan, working with a professional, now eradicates mature tree-of-heaven specimens with the use of a chemical herbicide applied to the trunk only. When the tree is dead, then it is physically removed. “We’re still working to fully eradicate ailanthus from Bidwell Park but haven’t achieved that goal yet (and of course, with so many female ailanthus trees around town, it will never really be achieved),” she writes with resignation. Photo: The spreading, mat forming tendrils of puncture vine, the spiked seed heads of which can puncture tires and otherwise attach themselves to feet and fur and be transported far and wide. These are best removed by hand-pulling and putting in the trash before seed has set. Weedy plants are best placed in the trash, rather than composted. The municipal landfill is sealed, Susan explains, and so seed or material that might sprout will be killed.

Susan’s two top pieces of advice to home gardeners working to remove invasive plants from their landscapes are to 1. do your homework by learning about the plant you are battling, for instance, many plants such as bind weed (Convolvulus arvensis), a member of the morning glory family; puncture vine (Tribulus terrestis) and English ivy (Hedera helix), regenerate quite easily either from nodes along stem pieces, or by many. many seed structures. To chop these plants up by mowing them, blowing their debris, or tilling them for instance, only increases their numbers.Photo: Invasive fig and seedling privet. If you have fruiting plants such as fig or olive in your home garden by choice, make concerted efforts to protect fruit from birds and to diligently harvest all fruit when ripe.

2. Plan in advance for removal. As we walked through ‘lost park,’ Susan pointed out that there was really one way in and out of the site, and prior to beginning privet removal with the crews of volunteers, Susan made sure a few months before removal began to come in and have volunteers first remove the large amounts of bur chervil (Anthriscus caucalis), before it had formed its sticky velcro-strong bur seed heads. Had this step not been considered, the crew of volunteers working to remove the Japanese privet would have made the park’s infestation of bur chervil worse by disturbing and then redistributing the chervil burs on their tools, their clothes, their shoes, etc.

Photo: Many horticultural plants that have escaped the garden and become invasive did so because they are attractive plants to look at. This is true of both pokeweed (Phytolacca americana), shown here, Queen Ann’s lace (Daucus carota), and many of the brooms. If you like the looks of these known invasive plants, try working with a plant person to find similar alternatives.

Here are some of Susan’s tips for working on invasive plant eradication:

Invasive Plant Control
Susan Mason

What should a gardener know before he/she starts to remove weeds?
• Identify what weeds you have and learn how each weed reproduces and spreads.
• Decide whether your goal is to eradicate, control or maintain the weed population.
• Based on that knowledge, decide how and when to remove specific weeds. Plan ahead so you’re not facing a huge weeding project just as you’re going on vacation.
• Prioritize your weed removal based on what you’ve learned about its reproduction and prevalence. Generally, work on small infestations first and then the larger areas. However, the number of seeds produced by an individual plant and the seed viability and longevity should also be considered.
• Try to identify new weeds while they’re small.
• When possible, remove weed before plant sets seed to reduce future populations. If not possible, try to contain seeds either by covering the plant with plastic, or hand-picking and collecting the seed in sealed plastic bags, before pulling, cutting or moving the whole plant, which will only spread the seeds.
• The California Invasive Plant Council (www.cal-ipc.org) is a great resource for plant identification, control methods, and training.

• Use tarping and mulches to reduce or eliminate weeding—cardboard is a great, free weed barrier in our Mediterranean climate and can even survive occasional rains; large pieces are available at bike and motorcycle shops, appliance stores.
• Keep buckets and gardening gloves around the yard to make it easy to do short weeding sessions.
• Use the right tool for the job and make sure it’s sharp (if it’s supposed to be). If possible, invest in higher-quality tools which work better and last many times longer than cheap tools.
• There are specialized tools for specific types of weed removal that can save time and reduce the effort of weeding.
• Buy tools with colored handles, wrap colored electrical tape on handles or paint handles to make it easier to find misplaced tools. Ditto for gardening gloves.
• Fiberglass tool handles last longer, but don’t have the shock-absorption characteristics of wood. Therefore, they’re good for shovels, not so good for axes and Pulaskis.
• Work with your neighbors to eliminate weed sources.

Avoid spreading invasive plants:
• Don’t accidentally spread weed seeds—wash equipment after working in or driving through weedy area, change clothing and shoes or remove weed seeds before moving to new area, work in weed-free areas first
• Don’t plant invasive plants. See Don’t Plant a Pest brochure (link below) for the horticultural plants that are the most invasive locally and for alternatives to plant that will not get out of control in your garden.
• Don’t dump grass clippings, yard waste, aquarium waste, or seeds and cuttings of horticultural plants in public open space areas or waterways. Not only is it generally as illegal as dumping trash, it can smother the native plants, increase bank erosion on creeks, and spread invasive plants to new locations.
• Be especially careful when gardening or working near waterways. To remove large items from a creekside, could increase erosion. To accidentally drop seed heads in a waterway will increase their dispersal and subsequent damage exponentially. If you are not sure, get advice from an authoritative source – see lists below. Photos above: Susan Mason, and a section of overgrowth in ‘Lost Park’.

In the Spring 2011 issue of the Butte Environmental Council (BEC) newsletter, Susan pointed out the following staggering statistics: “California spends $82 million per year to control, map, monitor and provide public outreach about weeds*. These invasive plants displace native plants and wildlife, increase wildfire and flood danger, consume valuable water, degrade recreational opportunities, and destroy productive range and timber lands. How did these plants get here? Some were brought in accidentally (e.g. yellow starthistle in the 1860’s as a seed contaminant of alfalfa), some drifted into California from adjacent states (northeast CA has more new weed introductions than anywhere else in the state) while others were deliberately introduced (horticultural plants). More than half of California’s invasive plants got their start in home gardens and commercial landscaping. At a local level, the Butte County Weed Management Area’s Noxious Weeds List of 22 plants includes 9 horticultural plants—fig, privet, ivy, periwinkle, Spanish & Scotch broom, giant reed, pampas grass, and tree-of-heaven.” Photo: Invasive star thistle. PHOTO COURTESY OF Sepulveda Wildlife Basin.

No gardener wants to be the person who plants a pest or helps to cause more invasive species to be introduced. If we as gardeners, as the consumers who create demand for certain plants, were indirectly or in ignorance, the cause of more than half the invasive plants out there, we can certainly do our due diligence and be more than half the solution. Susan Mason is here to help us learn how.

Susan Mason is increasingly doing more education and outreach in our area to help inform interested gardeners about more effective and efficient ways to deal with weedy and invasive plants. She writes quite regularly for the Friends of Bidwell Park newsletter and the Butte Environmental Council newsletter. In addition to her upcoming workshop on Septemeber 24th for the Chico State Herbarium, she will be teaching a similar class for the Butte County Resource Conservation District in Oroville in March.

Photo: Very invasive and toxic scotch broom.

To further help you do your homework, here are some excellent links to sources for more information on weeds of our area and/or how to work with removing them:

Central Valley Plant Right Brochure:

Friends of Bidwell Park http://www.friendsofbidwellpark.org/

Butte Environmental Council http://www.becnet.org/

Mt. Lassen Chapter, California Native Plant Society http://mountlassen.cnps.org/

Shasta Chapter, California Native Plant Society http://www.shastacnps.org/

No Ivy League:

PDFs of the Invasive Plants of California’s Wildlands


Cal-IPC Plant Inventory, where we collaboratively assessed the Impact, Invasiveness, Distribution, and Documentation Level for over 200 plants:

Statewide maps that indicate where invasive plants are currently located, if their populations are spreading, and how susceptible un-invaded area are:

The University of California, Davis Integrated Pest Management site, including plant pests http://www.ipm.ucdavis.edu/index.html

More of my environmental writing can be found in the Chico News & Review, and Pacific Horticulture. Follow Jewellgarden.com/In a North State Garden on Facebook.

To submit plant/gardening related events/classes to the Jewellgarden.com on-line Calendar of Regional Gardening Events, send the pertinent information to me at: Jennifer@jewellgarden.com

Did you know I send out a weekly email with information about upcoming topics and gardening related events in the North State region? If you would like to be added to the mailing list, send an email to Jennifer@jewellgarden.com.

In a North State Garden is a weekly Northstate Public Radio and web-based program celebrating the art, craft and science of home gardening in Northern California. It is made possible in part by the Gateway Science Museum – Exploring the Natural History of the North State and on the campus of CSU, Chico. In a North State Garden is conceived, written, photographed and hosted by Jennifer Jewell – all rights reserved jewellgarden.com. In a North State Garden airs on Northstate Public Radio Saturday mornings at 7:34 AM Pacific time and Sunday morning at 8:34 AM Pacific time. Podcasts of past shows are available here.

Jennifer Jewell
In a North State Garden is a bi-weekly North State Public Radio and web-based program celebrating the art, craft and science of home gardening in Northern California and made possible in part by the Gateway Science Museum - Exploring the Natural History of the North State and on the campus of CSU, Chico. In a North State Garden is conceived, written, photographed and hosted by Jennifer Jewell - all rights reserved jewellgarden.com. In a North State Garden airs on Northstate Public Radio Saturday morning at 7:34 AM Pacific time and Sunday morning at 8:34 AM Pacific time, two times a month.
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