Greetings Santa Fe Ranch Board Members and Concerned Residents:

Those of you who attended the annual Stagecoach Trails/Santa Fe Ranch Property Owners Meeting at the Yucca Fire Department on Saturday, Feb 19, 2005 will be aware of my public mention of the invasive and noxious weed known as Sahara mustard. This plant poses a severe threat to the ecological integrity and ultimately the property values of Santa Fe Ranch residents since it is capable of spreading aggressively into uninvaded regions and dominating the local plant communities in a way that is very detrimental to the long-term health and aesthetic value of the area. This email is intended to be an introductory one describing the plant and the threat it poses and what can be done about it to stop its spread in the Stagecoach Trails area.

Sahara mustard (Brassica tournefortii) is a plant of North African and Middle Eastern origin. According to the California Invasive Plant Council it was first discovered in California’s Imperial and Coachella Valleys in the 1920’s. Seeds were probably accidentally introduced to North America in the process of developing the date palm industry in those regions around the turn of the century, as date palms are also native to those regions of Africa and SW Asia. It was neither a problematic nor common weed for many years, but the aggressive spread of this plant began in earnest in the 1950’s. A succession of wet winters between 1977 and 1983 apparently led to an explosive increase in both plant density and areal coverage. For more information on the biology of Sahara mustard, read this link: http://ucce.ucdavis.edu/datastore/detailreport.cfm?usernumber=12&surveynumber=182 

Sahara mustard is now spreading in all directions from its original infestations in SE California. It is found in Mohave County at elevations between river level at 500 feet and plains and slopes and washes up to about 3500 feet, but is most common below 2000 feet in altitude. It is not clear when it arrived in our area, but the comprehensive guidebook Seed Plants of Northern Arizona published in 1973 doesn’t list it among the plants found in the area, so it is probably safe to assume that the invasion is less than 30 years old and has probably only become serious within the past 10 to 15 years.

Why is this plant such a problem? Why should Santa Fe Ranch residents be concerned? The reasons are several-fold:

1. As a non-native (exotic) species that originates in a similar climate far away from the normal biological control agents (insects, diseases, predators) that would ordinarily keep populations is check, it has a demonstrated capacity to occupy and overtake undisturbed natural ecosystems in the arid deserts of the American Southwest. Once established, it can increase explosively and crowd out desirable native plants. This will end up degrading local natural communities and completely restructure the functioning of the ecosystem, much to the detriment of the original occupants. Sahara mustard is capable of doing this without human assistance, which is why such species (plants or animals) are called invasive. There are many non-native and exotic plant species that are grown by humans for various reasons, but they may never escape cultivation and become invasive. Those that do, however, present major ecological threats in every conceivable environment. (Two other well-known invasive plants elsewhere in the US are Japanese kudzu, also known as “the vine that ate the South”, and the Amazonian water hyacinth that has choked waterways in warm-water regions worldwide including the US. I consider Sahara mustard the “desert kudzu”.)
2. Sahara mustard degrades rangeland, making it less useful for the majority of animals, including domestic livestock, which find it generally unpalatable and tend to prefer eating other items as opposed to the strong-flavored mustard plants. Being non-native and exotic in nature the local fauna (deer, desert tortoises, bighorn sheep, birds, insects, etc.) either do not eat it at all, or eat so little of it that it doesn’t help control the spread of the weed or benefit the animal populations in question. By crowding out and outcompeting more useful native plants, Sahara mustard causes declines in local animal populations.
3. Since Sahara mustard is an annual weed, meaning that it reproduces strictly from seed as opposed to having a perennial root system that allows the same plants to survive for many years, it grows during wet years, sets seeds, and then dies back, leaving its dead remains behind for as long as it takes for them to degrade back into the environment. Heavy infestations that grow during wet years will die before summer arrives. Those dead stems can then carry fire in the dry summer season, when lightning storms can ignite wildfires. Of course human-caused fires can also occur at almost any time of year, with or without lightning. Fire is not a natural part of the desert ecosystem, despite what many people might think. Unlike wetter and more heavily vegetated biomes, deserts have such sparse plant cover that under normal circumstances there is not adequate fuel load to carry fire from plant to plant. As such, even though a direct lightning strike on a given plant might ignite and burn that individual, the fire will not spread for lack of fuel in between adjacent trees or shrubs. Sahara mustard changes this dynamic by offering a fuel source in the spaces between plants, allowing small, local fires to potentially become large, devastating ones. Since desert plants in Arizona did not evolve with any resistance to fire, they die when fires do occur and seldom are capable of regenerating from the root system or seeds that thrive in scorched open terrain, unlike plants in fire-adapted ecological communities like chaparral. Since the mustards survive fires as seeds that lie dormant in the soil, they are unaffected by burning and in fact are ultimately favored by it since the other competing vegetation is reduced or removed altogether, allowing the vicious cycle to continue. And wildfires are an obvious threat to homes and other human endeavors.
4. One perhaps less tangible problem is the issue of aesthetic degradation on a landscape-wide scale that occurs when ugly and aggressive invasives like Sahara mustard take away the diverse and regionally characteristic flora and replace it with a useless near-monoculture of weeds that can be found everywhere. One of the best things about living in the deserts of Arizona, Santa Fe Ranch included, is the dramatic and glorious displays of annual and perennial wildflowers that occur in wet years. Sahara mustard overrides and outcompetes the annual flowers, commandeering almost all of the available space and water and nutrients for itself. While it is not strictly necessary to have mass bloomings of spring flowers, why on earth would we want to see them become a thing of the past thanks to an unattractive insidious weed? See this link from the Arizona-Sonora Desert Museum to see photos of how the mustard has eliminated the mass wildflower blooming displays that once occurred over large areas of the Lower Colorado River Valley, which the Santa Fe Ranch is part of: http://www.desertmuseum.org/programs/flora_bratou-gallery.htm

We here at Santa Fe Ranch face a mixed bag of opportunities and problems when faced with the threat of this noxious weed coming into our beloved and relatively pristine area. The weed is not found yet over large areas of the ranch, although there are several zones of serious infestation in other large areas that may not be totally controllable until an effective biological control agent is found and introduced to help reduce the populations and stall the spread of the plant. I need to do a reconnaissance of the areas of our ranch that have mustards and get a rough idea of how bad the problem is and where it lies, and I can report the findings to you when I achieve this. (I hope to do this within the next week or so.)

Generally speaking, however, the lower reaches of the Santa Fe Ranch nearest Yucca and the I-40 corridor are the most heavily impacted by the presence of mustards at this time. The mustards probably first came into Mohave County and Dutch Flat along the interstate highway, and therefore those I-40 regions have had the most time for the mustard to reproduce and take over. The next time you drive on I-40 to Lake Havasu pay some attention to just how thick this stuff has grown alongside the freeway, and you will get a glimpse of what could be in store for us at Santa Fe Ranch if we don’t try to stop it from further incursion….

Some Stagecoach Trails properties off of the Santa Fe Ranch Road exit are entirely overrun, whereas others a bit farther up the same road are at a moderate grade of infestation. I have seen outposts of mustard along Alamo Road as far as the intersection with Knox Road, and on Santa Fe Ranch Road as far up as Rainbow Drive. Areas further south and east of those areas have little to no mustard, which means that there is a very good chance that informed homeowners can stop it from spreading onto their parcels or onto neighboring ones beyond them. Although I haven’t yet verified this, I am pretty sure that this plant is found abundantly along the Pipeline Road, which has been in existence for many years and probably has had the chance to develop a significant invasion. How far east of Pipeline it goes is something that I will have to see and report on shortly. My goal is to demarcate a “line in the sand”, beyond which we are able through informed action to prevent this noxious plant from spreading.

The main strategy the mustard uses to survive and spread is by producing abundant numbers of seeds and by adopting the lifestyle of a tumbleweed. Hefty specimens develop a large rounded crown that sooner or later dries and breaks off at soil level in the wind; then the plants blow through the desert and scatter seeds widely, creating spotty new infestations that gradually coalesce into a united front of invasion. In addition to this strategy the seeds have a sticky coat that turns gelatinous with rainfall. The sticky wet seeds can then adhere to passing animals, people, or vehicles and drop off a long distance away from the nearest parent population. Since plants are self-fertile, meaning they need no cross-pollination with other individuals, even a single seed is capable of reproducing and leapfrogging far ahead of the main advancing front into otherwise unsettled regions. This is why it is so important to recognize the plant and the threat it poses.

Sahara Mustard Weed Pictures

What is the best way to handle it? The main answer that I can offer to that question is hand-pulling, especially prior to their ability to set any mature seeds. Herbicides are very expensive, toxic, and impractical to use, because they will kill much more than just the mustards. No biocontrol options currently exist. Hand weeding is effective in small or low-density populations, especially since the plants pull easily and die quickly in the desert sun once uprooted. Most people who see an occasional mustard plant or a few patches of them don’t recognize the threat this thing poses. They understandably assume that there is no eco-disaster waiting to happen and allow them to reproduce and multiply by the aforementioned means. Once you have hundreds of individuals and a bank of seed stored in the soil, control requires some persistent hand-pulling every year until the seed soil bank is exhausted and no new ones emerge. If a population gets much beyond this level, control becomes nigh well impossible without incredibly difficult or time-consuming effort.

I have been weeding out spotty early-stage populations of Sahara mustard whenever I find them in largely uninvaded areas, although this is a task that no one person can ever hope to effectively do over large areas, especially on the millions of acres of public lands found in our area. But one effect of my extensive one-man effort to halt this pest’s range extension is the fact that I have been getting increasingly familiar with how it behaves, grows, and spreads, which means that the information gleaned can be used to more effectively advise people on how to handle it. To list all of the fine points of that effort would be to make this already long email too long, but I will happily write out the information soon and post it on my website so that people can link to it and read my helpful Martha Stewart-esque tips on weeding the wilderness. J I’ll soon have photos of my own to add to that discourse; they are being developed and need to be scanned and posted on my website and when this is done I will let everyone know.

Well, this about covers my introduction to the issue of the Sahara mustard. It is my hope and goal that by tackling the problem with focused effort now that we can stymie the looming problems posed by this obnoxious pest. Given how a majority of the ranch is not yet invaded this is a very realistic possible goal. But if nothing is done and the invasion is left unchecked we will absolutely see high populations of this plant everywhere on Santa Fe Ranch, as basically the entire range we collectively inhabit is suitable for it to survive and thrive. This may take 10 to 20 more years to happen, but that is not all that far away. Or it could be less than that if we get a series of wet winters that encourage a rapid population explosion. No matter how long it might take, one thing is for certain: Once this weed’s population gets too high, it will be impossible to reverse. This is why prevention is of paramount importance.

I will report my findings on where the various levels of invasion are, and try to make some recommendations on how to best inform individual property owners about this threat. There is no way that we can beat this problem given the acreages involved without a large majority of individual property owners in uninfested areas taking simple preventative actions, which is basically to put out every little “spot fire” of new plants wherever they occur. This is actually a very easy job as long as you know what the plant looks like and are willing to take a minute or two to check for it this spring and in future ones along the roadsides and parking areas and on your property margins, which are where the first flare-ups are likely to happen. Uprooting a few plants takes mere seconds and stops the problem in its tracks, although vigilance will be required for the long run. If you are in an infested area your options are more limited and/or more difficult to implement, but help may exist as we learn how to defeat this new threat together.

I thank you all for your patience in reading this. I will be happy to write a much shorter and more condensed version of this report for the homeowner’s newsletter when the next issue is ready to be sent. It is of paramount importance to try to stop this plant from getting any worse in a very wet year such as this one since the plants do most of their worst invasion in wet years. In dry ones they are not visibly present at all, but as long as there are viable seeds in the soil and without a working biological control method, we are under some threat.

Sincerely,

Jan Emming
www.dfranch.com
(928) 766 – 2597

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Santa Fe Ranch Property Owners Association, Inc. at Stagecoach Trails
1834 Highway 95 ~ Bullhead City, AZ 85442
800-345-5026 ~ 928-763-2740
www.santaferanch.org - Contact Board of Directors & Association Manager