What are invasive species?
Invasive species are organisms that are not indigenous, or native, to a particular area. Not all non-native species are invasive. To be considered invasive, an introduced plant species must meet these criteria, established by the EPA:
- Has few germination requirements, enabling it to adapt to the new environment easily
- Grows rapidly
- A prolific seed producer with effective dispersal systems
- Free of natural enemies and diseases
- Harms the environment, property, the economy, or the native plants and animals of the region
Plant Invasion in California's Central Valley
Of the invasive species listed on the California Invasive Plant Council Inventory, about 37% were accidentally introduced to the state. The remaining 63%, however, were intentionally introduced for purposes such as landscape ornamentals, soil stabilization, animal forage, human food, fiber, or medicinal.
Role of Plant Nurseries
University of California Integrated Pest Management has a Pest Notes link on invasive plants (http://ipm.ucanr.edu/PMG/PESTNOTES/pn74139.html) which lists the results of UC Master Gardener surveys of invasive plants for sale in California nurseries. Invasive plants rarely or no longer sold are listed.
What Can We Do?
Some ways you can help:
- Educate yourself regarding California's invasive horticultural plants, avoid planting them, and plant their alternatives for your garden.
- If an invasive plant already exists in your garden, at the very least, the plant should be kept in a vegetative state, so it does not reproduce. If you choose to remove these plants, it is important to make sure reproductive parts do not escape during the removal process.
- Do not to transport any reproductive parts such as fruit, seed, or root pieces by animal, human or vehicle to areas where plants have not been established. If you go camping or hiking in nature, clean your camping and hiking gear to ensure you are not accidentally spreading hitchhiking invasive species. If you bring a dog(s) along, clean their fur before leaving the park or wilderness area. Stay on designated trails and roads.
- Encourage local nurseries and garden centers not to sell invasive plants.
- Join removal efforts. Chances are you can find invasive species volunteer opportunities nearby. Check out your closest state or national park's website to see if they host invasive species walks—many organize half-day or day hikes where you learn to identify and help remove invasive plants.
Becoming a part of ongoing efforts to manage or eradicate the invasive non-native plant species in our state will help reduce their negative impacts on our natural resources. Planting native beauties in your garden is a simple way to help these plants survive and benefit the local fauna food webs.
- UC IPM - Invasive Plants: http://ipm.ucanr.edu/PMG/PESTNOTES/pn74139.html
- Plant Right - PlantRight is a project that was developed and managed by Sustainable Conservation, a California-based environmental nonprofit, from 2005-2019. In 2019, the new home of PlantRight became Plant California Alliance, which was formed through the merger of the California Association of Nurseries and Garden Centers, and the Nursery Growers Association. Includes a list of invasive plants in selected regions of CA and native substitutes: https://plantright.org/
- California Invasive Plant Council: https://www.cal-ipc.org/
- A list of plants not to put in your garden and alternatives: https://wildlife.ca.gov/Conservation/Plants/dont-plant-me
- PlayCleanGo provides ways for stopping the spread of invasive species: https://playcleango.org
Denise Godbout-Avant has been a UCCE Stanislaus County Master Gardener since 2020.
If you missed our planting and pruning Bare Root Fruit Trees Class, you can watch the recording on our UCCE Stanislaus County Master Gardener YouTube Channel. The class includes information on deciduous fruit trees, including apple, pear, cherry, nectarine, peach, plum, and apricot.
What about Citrus?
Citrus trees such as oranges, lemons, grapefruits and kumquats are evergreen trees and need different care than deciduous trees. Our program will offer an online class on March 22 on Caring for Citrus. Registration coming in early March 2022./h4>
- Author: Denise Godbout-Avant
Seasonal Landscape IPM Checklist for Home Gardeners
UC's Integrated Pest Management (IPM) Home, Garden, Turf and Landscape Pests Quick Link has a Seasonal Landscape IPM Checklist which is a wonderful resource with monthly checklists within your selected county/region to help guide you how to keep your landscapes healthy.
Topics include common pest problems to look out for, preventative measures, and links to more information. You can also subscribe to receive an automated monthly list by email.
December and January Lists
I reviewed the December and January checklists for Stanislaus County. The following are some topics listed and additional appropriate links:
- Frost – Temperatures sometimes drop to freezing during the winter months. Cold temperature can kill bark, buds, flowers, and shoots, so protect sensitive plants from frost. To increase a soil's ability to absorb heat rake away mulch to expose the ground around the base of the plant. If frost is expected irrigate the soil (if there hasn't been any rain recently) at least three days prior. You can also cover sensitive plants overnight with cloth or similar material other than plastic but leave covers open at the bottom so heat from soil can help warm plants and remove covers during the daytime. http://ipm.ucanr.edu/PMG/GARDEN/ENVIRON/frostdamage.html
- Irrigation – Always adjust your watering schedule according to the weather. We have had a very wet December, which followed an atmospheric river storm in October. So, gardens have needed little to no irrigation lately, depending on your soil type. Overirrigation can lead to root rot. Resume irrigation if storms diminish during the remainder of the winter (let's hope it remains wet!). If there is an extended dry spell during upcoming winter months, irrigate infrequently and deeply. http://ipm.ucanr.edu/homegarden/irrigating/
- Clean up – Remove old fruit and nuts in and under trees to avoid harboring pests. Also rake up fallen leaves beneath deciduous fruit trees and roses (but leave the leaves elsewhere in your yard for beneficial overwintering insects including butterflies and bees). http://ipm.ucanr.edu/PMG/GARDEN/FRUIT/CULTURAL/sanitation.html
- Prune – Trees and shrubs that need pruning including apple, crepe myrtle, pear, rose, spirea, and stone fruits (exception are apricot and cherry trees which can harbor certain pests, i.e. shothole borer, which should be pruned in the summer). Remove dead and diseased wood. http://ipm.ucanr.edu/homegarden/pruning/
- Mistletoe – Mistletoes are parasitic plants that absorb nutrients and water from a host tree. Healthy trees can tolerate a few branches infected with mistletoe, but a heavy infestation could ultimately kill a tree, particularly if the tree is stressed or unhealthy. With leaves having dropped during fall months from deciduous trees, mistletoe is visible on the now-bare trees, and thus can be removed easily. Remove branches at least a foot below the mistletoe attachment before it produces seeds that will infest other limbs and trees. Since mistletoe often infects many trees on the same street, a neighborhood effort to remove all mistletoe from any trees on the block will help reduce continued spread in the area. http://ipm.ucanr.edu/QT/mistletoecard.html
- Peach leaf curl –If leaf curl has been an issue on your peach or nectarine plants apply preventive spray once or more times until bud break. http://ipm.ucanr.edu/QT/peachleafcurlcard.html
- Bare root plants – Now is the time to plant bare root deciduous trees, shrubs, and vines, including roses, fruit, nuts and grapes. Select species and cultivars that are appropriate for the site it is being planted. http://ipm.ucanr.edu/homegarden/planting/
This compilation is a partial overview of the lists I reviewed. Check out the January seasonal landscape checklist for your area to see which tasks you need to do. Then bundle up, get your garden tools, and go outside (preferably on a sunny day!) to do the necessary winter maintenance chores in your garden. You and your landscape will be rewarded for your cold weather efforts come spring.
Denise Godbout-Avant has been a UCCE Stanislaus County Master Gardener since July 2020./h3>
Where: On Zoom. You will receive a link the morning of the class.
When: Tuesday, June 29, 2021 6:00-7:30 p.m.
Register at: http://ucanr.edu/water-wise/2021
Instructors: Instructors Denise Godbout-Avant and Johnny Mullins
The recording will be posted to our YouTube channel at http://ucanr.edu/youtube/ucmgstanislaus
- Author: Denise Godbout-Avant
According to UC Integrated Pest Management (UC IPM), aphids are small, soft pear-shaped bodied insects with long legs and antennae, with slender mouthparts used to pierce stems, leaves and other tender plant parts to suck out plant fluids. The site recommends first attempting to control aphids by washing them off with a gentle stream of water. I did this over several mornings and evenings, with my hose set on fine spray, washing both the top and underside of the leaves. After about a week, I still had quite a few aphids, so I sprayed an insecticidal soap, making sure I covered both the top and bottom of leaves. Aphids produce many offspring, so they required an additional treatment.
Soft scale is a sucking insect, appearing as tiny dots on the leaves or stems of a plant. They can grow up to ¼ inch long and have a smooth, cottony or waxy surface. They feed on the sap of the plant and excrete sticky honeydew, which can attract ants. Mine were brownish-yellow with a waxy color, usually appearing on the underside of the leaves.
I removed badly damaged leaves, checked undersides of the leaves for the scale and scraped off any scale I found using a wet Q-tip. I also checked my other two plants and occasionally found a scale or two on them, scraping them off also. I repotted the infested plant with potting mix. Over time I was able to completely get rid of the soft scale.
My Buggy Summer Summary
It has been an educational summer learning about these insect pests and dealing with their infestations. I'm gratified I've been able to manage them using less toxic pesticides that are less harmful to beneficial insects and the environment. You can learn more about less toxic pesticides such as insecticidal soaps and oils by visiting the UC IPM website or by watching this video.
Denise is a UCCE Stanislaus County Master Gardener.