- Author: Kathy Keatley Garvey
Honey bees and native bees love capeweed, Arctotheca calendula, also called South African capeweed, cape dandelion and cape marigold or cape gold.
It's an invasive plant originating from the Cape Province in South Africa (Here's what the California Invasive Council says about it:
"Capeweed (Arctotheca calendula) is an annual or perennial evergreen herb that, when young, forms a low-growing rosette of heavily pinnately lobed leaves, with undersides covered by woolly down. With age, it forms an extensive, dense, mat-like groundcover by proliferation of rooting stems (stolons) from rosettes. Leaves are pinnately lobed; fine, dense hairs cause stems and leaves to appear silvery. Flowers are approximately two inches in diameter, lemon yellow, and daisy-like with yellow centers. The plant is conspicuous in late spring and early summer due to its increase in size and the profusion of large yellow daisies. Plants are seldom solitary, and they spread vigorously by creeping stems (Lasca Leaves 1968)."
Capeweed may have arrived in California in a shipment of grass seed from Australia, where it is a common weed, according to the California Department of Food and Agriculture. The invasive species compendium (CABI) listed it as a noxious weed in 2010 in California.
However, it's cultivated as an ornamental ground cover and has both "fertile" and "sterile" forms.
We've seen lawnmowers run over the the weed in City of Benicia parks (yes, it grows back), we've seen it thriving in a gold carpet along coastal California, and we've seen bees foraging on it.
It's a pollinator paradise, of sorts, but it's also invasive.
- Author: Thomas Getts
- Posted by: Gale Perez
From the Lassen county Farm Advisor's Update newsletter (Aug. 2020)
Highlighting Two Uncommon Noxious Weeds
Let's keep them uncommon!
I'll start with rush skeleton weed. It is relatively difficult to identify when it is young. The leaves and rosettes look fairly similar to a dandelions. As the growing season progresses, it sends up long spindly shoots as it bolts in early summer. After it bolts it looks quite a bit like chicory, but it is much more invasive. (Chicory has larger blue or white flowers.) Eventually it develops a yellow flower and seeds like a dandelion that can blow in the wind.
This plant is not widespread in California and is considered an A-list noxious weed on the old noxious weed list. The map from Cal Flora shows where is has been officially documented within the state. There have been sightings in Plumas county, a couple in Shasta, and there is an established population on the west shore of Honey Lake. I wouldn't be surprised if there are other populations around our region which do not show up on the map!
Skeleton weed has the potential to expand in the Intermountain region, overtaking rangeland and dryland pastures. In conversations I have had with weed scientist Tim Prather, skeleton weed has completely escaped control in his state of Idaho. It has established on over 3 million acres in the mountains of Idaho, and in many parts of eastern Washington. Skeleton weed is not just problematic here in the western US, but is also a problematic plant in dryland wheat production in Western Australia and parts of Argentina. Keep your eye out for it, so we can prevent it from overtaking our landscapes!
Skeleton weed is not desirable forage for livestock or wildlife, and grazing tends to promote skeleton weed over other species that are more desirable. Generally, mechanical control is not effective for established plants because of the deep root system. However, there are multiple biocontrol agents established in the state. A rust, a gall forming midge, and a gall forming mite can all help reduce spread, but not eliminate populations.
Like many deep-rooted perennial weeds, herbicides are often relied upon to control established skeleton weed patches. The best time to make applications is in the rosette stage. If you do find a population on your property, mark the area out now while you can find the plants and see the flowers. The next year, finding the rosette will be easier. Feel free to give me a call to discuss what control options might be best utilized for your situation.
Previously, sulfur cinquefoil was considered an A-list noxious weed, but its status is under evaluation, as many noxious designations are. Regardless of the category it is listed under, it is still a noxious weed, and not one we want to let take over our landscapes. It has the ability to spread by seed, as well as by root, and established plants can live up to 20 years forming a woody crown.
One key characteristic of sulfur cinquefoil compared to other cinquefoils is the stiff hairs that stick straight out from the stem. Many other native cinquefoils have hairs that lay flat on the stem. This can be key to help identify the noxious weed before it goes to flower.
Controlling weeds while patches are small can pay large dividends on efforts needed in the future. If you suspect you may have either of these species, let's eliminate them before their populations really get started in our region.
Original source: Lassen county Farm Advisor's Update newsletter (Aug. 2020)
- Author: Ben Faber
- Re-posted by: Gale Perez
From the Topics in the Subtropics blog :: March 4, 2020
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So I've gotten a few calls lately about this vine with a big green pod that is growing in lemon trees. What is done with it and how do you get rid of it?
Araujia sericifera, cruel vine, moth plant, bladderflower is an escaped ornamental that has become an invasive weed in California. Yes, a pretty vine brought into the garden – “poor man's stephanotis” - and it's gotten out of the garden into southern California. It's in the hills, in abandoned orchards, on backyard fences and when it gets into a lemon tree, it takes some effort to remove it before the seeds spread to other trees and beyond.
Bladderflower is a perennial vine that is very vigorous where it gets summer water. It is a common weed in citrus groves, where it would enshroud & smother entire trees if not controlled. Stems are tough and ropy, leaves thick and slightly spongy. Sap is milky white, moderately poisonous and causes skin irritation. It flowers Aug-Oct and the seed pods are obvious later in the fall. The flowers have a pleasant fragrance like jasmine. The reason for gardeners planting it. Plus it grows fast in our environment.
So the vine is entrained in the tree canopy so you can't spray an herbicide. To get rid of it, it's important to get down to the base of the tree and cut it out at ground level, removing as much of the root as possible. It still can regenerate, so it will be necessary to monitor the site, removing new growth as it might happen. Be sure to use hand protection because many people are allergic to the sap. Just cutting the vine at its base is sufficient to kill it. Removing the rest of the vine is necessary if there are pods, in order to prevent them going to seed.
The upside of the plant aside from the fragrant flowers is that it is an alternative food source for monarch butterfly caterpillars.
Calfflora shows cruel vine spread mostly along the coast south of San Luis Obispo, but it has the potential to spread thoguhout much of California. Currently, in the US, it is only found in California and Georgia. It is in New Zealand and Australia.
Calflora Description and Distribution of Bladderflower
USDA Description of Plant as attachment below:
Araujia sericifera WRA
- Author: Thomas Getts
When I was an undergraduate back in Colorado, I spent the vast majority of two summers mapping the waterways of Boulder County for invasive species. It was an excellent experience which got me jazzed about weed science. Fighting through the thorns of Russian olive groves, while picking the cheatgrass and houndstongue seeds out of my socks, I was experiencing first hand some of the impacts invasive species have. I quickly realized my discomfort was trivial to the impact these invasive weeds were having on native species.
One of the plants the Land Manager of Boulder County was most concerned about was myrtle spurge (Euphorbia myrsinites L.). Back in Colorado this creeping perennial is an A list noxious weed species with limited distribution. Myrtle spurge, or the common name I prefer, donkey tail, is sold as an ornamental plant. I have to admit it is a really cool looking plant! But myrtle spurge can act invasive, displacing native species in dry rocky areas. Additionally, it's milky white sap can cause contact dermatitis. Fortunately, the populations were limited in that area as I only ran across two patches, over a couple hundred miles of waterways mapped those summers.
A few months ago up here in Lassen County, the BLM Eagle Lake Field Office's weed specialist was contacted by a land owner who noticed a suspicious plant spreading outside of landscape plantings in his rural community. Upon further investigation by the BLM, the plant was identified as myrtle spurge. Quickly, one of the Lassen County Agricultural Commissioner's biologists was contacted to collect a specimen to send down to the CDFA botany lab. Unfortunately, the CDFA confirmed the initial identification, and the presence of myrtle spurge was confirmed. As myrtle spurge has been documented as invasive in other western states, the California Department of Food and Agriculture listed it with a Q designation.
I heard about the population from the BLM, and was able to swing by the infestation on the way to some of my field plots. Sure enough, there it was, loads of donkey tail in full bloom! The grayish green foliage with vibrant yellow flowers was dotting the subdivision, and peppering the roadsides. I had no problem envisioning the invasion out into the rocky sagebrush described to me by my friends at the BLM and Ag Commissioner's office. Fortunately, the myrtle spurge population still appears to be relatively small. Hopefully this turns into a success story of early detection and rapid response, so we can keep another invasive weed from gaining a foothold in our state!
A few days ago there was a post about on the CDFA's website regarding the noxious status of myrtle spurge. It is being proposed to change the myrtle spurge listing from Q to A, and currently comments are being sought until the end of August. I encourage you to take a moment and visit the link below to the CDFA's website. There is a very informative write up about myrtle spurge, along with a detailed layout of the ranking system used to determine the proposed change in noxious weed classification.
By Michele Carter, Butte County Master Gardener, July 12, 2013
Yellow starthistle seeds germinate from fall through spring, corresponding to the normal rainy season in California. After germinating, the plant allocates most of its resources to root growth and by late spring, roots can extend over 3 feet. The plant exists as a short rosette amongst other weeds until it begins to flower.
The foliage of this plant ranges from gray-green to blue-green; once flowering begins it can easily be identified by its bright, thistle-like yellow flowers, which have sharp spines surrounding their bases. This weed grows from 6 inches to up to 5 feet.
Yellow starthistle forms dense infestations and rapidly depletes soil moisture, preventing the establishment of other species. It is also poisonous to horses, causing a nervous disorder called “chewing disease” (nigropallidal encephalomalacia), which is fatal once symptoms develop. Horses are the only animal known to be affected – they should not be allowed to graze on yellow starthistle.
Yellow starthistle can be spread as a contaminant in grass seed and in all classes of hay, particularly grass hay. Hay used as mulch along roadsides or disturbed areas can be a source of yellow starthistle. Livestock that have fed in areas infested with yellow starthistle can be transporters of the seed.
Because the seeds germinate during the rainy season, a single cultivation after the rainy season, when soils are dry, effectively controls yellow starthistle seedlings and rosettes. Timing is critical: this cultivation must take place in late spring after the last rains but before seeds are produced.
Mowing can be used to manage starthistle. Be sure to mow well before starthistle is in full flower or has set seed. Mowing is most effective when soil moisture is low and no irrigation or rainfall follows mowing. If rain occurs after you've removed existing plants, seeds will continue to germinate and the eradication process must be repeated. Pre-emergent and post-emergent herbicides can also be helpful in controlling growth and infestation of starthistle.
Lastly, effective management of starthistle includes revegetation. Planting affected areas with desirable plants discourages starthistle regrowth by creating competition.
For information about herbicides and for photos of yellow starthistle's growth cycle, visit http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7402.html
