Posts Tagged: broom
Home Heating and Clean Air Yard Care
The San Joaquin Valley continues to face many air quality challenges as it strives to meet federal...
Invasive Plants.
By Susanne von Rosenberg, UC Master Gardener of Napa County One thing that Master...
Don't plant a pest! (cal-ipc.org)
Pampas grass--invasive plant in California. (westcoastseeds.com)
Scotch broom--invasive plant in California. (gardeningknowhow.com)
Cal-IPC. https://www.cal-ipc.org/ (wra-ca-com)
Calflora--check website for information on wild California plants. https://www.calflora.org/ (csumb.edu)
Don't let your garden be invaded by planting invasives. (selfsufficientculture.com)
Don't plant a tree pest, either. (cal-ipc.org)
Sleuthing a New Devastating Disease
So Sphaeropsis tumefaciens causes galls, but it's also been noted to cause witches broom in citrus, as well. Thjs type of broom formation is a wild, though compact growth. It's a dense mass of shoot growth from a single point – a messy mass that even a witch would have a problem using to sweep up. This is a symptom of infection by certain fungi, like rust or mildew or a genetic mutation in the plant itself. If it's a stable genetic change that doesn't alter over time, it could be used in the horticultural trade to propagate dwarfing plants. That might be good in the case of citrus, meaning less pruning. There's already the ‘Flying Dragon' rootstock that causes dwarfing, but it has some problems, like being really slow growing.
Anyway, another cause of undisciplined broom growth is phytoplasma infection. These are bacteria-like organisms that were only discovered in the 1960s and cannot be cultured. This makes it hard to work with them. They can cause debilitating weaknesses in plants besides the broom growth. To complicate the culturing issue, it has a conspirator, which needs to be understood, as well. The phytoplasma is spread by an insect, the same way the Liberibacter bacteria is spread by Asian Citrus Psyllid, causing HLB. So it's necessary to know the biologies of two actors, plus how they interact. The problem of HLB, again.
In India and Iran, there is a crippling disease of lime caused by a phytoplasma that is spread by leafhoppers. You need the specific leafhopper to spread the phytoplasma to spread the disease. No leafhopper and it's unlikely that even if the phytoplasma were here, that it would get spread.
The internet is democratizing. It spreads all kinds of information equally to everyone. So an image comes across my computer, asking if I think the wild growth on the ‘Pixie' mandarin is this WBDL (Witches' Broom Disease of Lime). I don't think so, but you never know what is going to pop up. I was thinking it's probably Sphaeropsis on a new track, and whatever, need to check it out.
And there it is. The wild growth. It fills about a third of the canopy of the little tree.
There's even this flattened stem. Truly weird.
But something does not look right. Is it the phytoplasma causing other types of growth? The leaves don't look right. Citrus leaves have a central vein, with lateral veins. The leaves on the affected part of the tree only have a single mid-vein.
This is not a citrus growth deformity. This is some other plant. Following the stem of the deformed branch to the base of the trunk, there's the “sucker”. And it doesn't look like citrus bark.
This is not even a citrus plant. At some point, a myoporum seedling started growing there. The leaves are similar enough to citrus, that the grower thought it was a citrus branch than had become infected. Well, the myoporum did become ‘infected'. With what, I'm not sure. It could easily have been Sphaeropsis since it is in the Ojai area. Anyway, “when it doubt, cut it out”.
And here is the neat little tree, a third of it gone now and the interior exposed to sun so that it will need to be whitewashed to protect it from sun damage. But, it's not WBDL. This time. It's important to keep looking for what nature and hitchhikers can bring us. It could be a whole lot more serious.
Invasive Plants: Don't Encourage 'Bad Neighbors'
What do ice cream, potato chips, Scotch and Spanish Broom, and Tree of Heaven have in common? While they're all tempting to indulge in, less is more. In fact, plants such as Scotch, Spanish Broom, Tree of Heaven, Pampas Grass, Green Fountain Grass, and dozens of plants are all considered invasive plants in California. Simply put, they should not be planted. There are some great alternative plants that are better choices listed at the end of this blog.
Truth be told, I admit to falling madly in love with the Spanish Broom (Spartium junceum) shrubs adorning Highway 18 on my drive from San Bernardino to Lake Arrowhead in early spring 1984 right after my job interview for my current position. Being a “wet behind the ears” recently hatched graduate student from the Midwest I was truly in awe of their lovely yellow blooms and vowed to plant one if I got the chance to move to California. Fortunately, I found out very soon that, while the plantings were made on purpose, they were a mistake and needed to be removed due to their invasive nature.
While they were ‘recruited' from Europe and had what seemed like a perfect resumé (fast growth, lovely yellow flowers, adaptability to poor infertile soil and disease and insect-resistance), they didn't play well with others, a fatal flaw. In California, they were aggressive and crowded out native plantings. Fires only exacerbated the situation. After the 2003 burns, the Spanish Broom populations exploded, obliterating any remaining natives and taking an even larger area hostage. In summer 2010, the San Bernardino National Forest removed the plants in a costly but necessary $500,000 project under a partnership with the American Recovery and Reinvestment Act. Constant monitoring continues in the San Bernardino Mountains and other areas of the state to prevent its reestablishment which is challenging due to its ability to quickly resprout, seed longevity, and effective dispersal. It has definitely earned its ‘noxious weed' label!
This is just one example of the problems posed by invasive plants. In effect, they grow too well! They outcompete desirable plants in our gardens, lawns, and other urban and natural areas for water, nutrients, and space. They also shade sun-requiring plants. Threatened and endangered plant species and other California native plants are particularly vulnerable to their encroachment. (In most cases, invasive plants are non-native species.) Interestingly, our beloved state flower, the California poppy, is an invasive plant in New Zealand, Hawaii and other locations outside of California.
As urban gardeners, we can all greatly reduce the impact of the encroachment of invasive plants in our urban environments. Please don't plant invasive sane remove plantings on your property to stop their spread. Below are some great resources to learn more about invasive plants and find viable replacements:
California Invasive Plant Council: https://www.cal-ipc.org/
Don't Plant a Pest: https://www.cal-ipc.org/solutions/prevention/landscaping/dpp/
Invasive Plants of Southern California:https://www.cal-ipc.org/solutions/prevention/landscaping/dpp/?region=socal
PlantRight: https://plantright.org/about-invasive-plants/plant
Keep An Eye Out for Invasives.
by Penny Pawl, U.C. Master Gardener of Napa County Oh no, I've done it again. I have fallen in...
Pampas grass (Direct Gardening)
Mullein (California Invasive Plant Council)
Butterfly bush (Monrovia)
Watsonia (PlantZAfrica-SANBI)
Privet (Jack Kelly Clark, UC IPM)
Bamboo (Jack Kelly Clark, UC IPM)
Scotch broom (UC ANR)
Pride of Madeira (California IPC)
Honeysuckle (Cheryl A. Reynolds, UC IPM)
https://www.cal-ipc.org/plants/profiles/