Garlic+Mustard

=Controlling the invasive species of Garlic Mustard (Dylan, Elliot, Anthony)= //"you guys have a great project"- Ranger Mark//

= = =** Introduction **=

For this year’s Watershed Project, our Group – Elliot, Dylan, and Anthony – decided to find the best method to control the spread of the invasive species Garlic Mustard. Through a series of experiments our group was able to find the answer. Our group had considered a number of possible ways to control the Garlic Mustard from spreading. First we thought of using an organic weed killer – comprised of 4 cups vinegar, ½ cup of salt, and two teaspoons of dish detergent. However, Ranger Mark informed us that if we were to go with that experiment, our group wouldn’t see viable results for nearly two years. In addition, Ranger Mark also told us that if we were to use a weed killer the best time of year for that particular experiment would have been in the fall. What's more, we could be harming nearby species. Next we considered mechanically pulling out the Garlic Mustard from the roots. However, the park ranger also informed us that Garlic Mustard grows more easily in disturbed soil. Therefore if we were to pull the weed up by its roots, it would temporarily reduce the amount of Garlic Mustard; however, in the long run it would be harmful because it would make it easier for future Garlic Mustard plants to grow. Finally, Ranger Mark and our group agreed on two experiments that would best control the Garlic Mustard plant problem.

= Hypothesis = Our group believes that the best way to control the Garlic Mustard epidemic is to manually cut the stems approximately one inch from the ground.

= Abstract = Our group cut the stems of Garlic Mustard in two different spots – one spot was cut one inch from the ground and the other was cut right bellow the seedpods/stems. After two designated time periods our group measured the change in growth. Based on our results we concluded that our hypothesis was correct because the stems that were cut only one inch from the ground grew fewer flowers. A further analysis of this is seen in our conclusion.

=** Background Information **= The correct name for the Garlic Mustard species is //Alliaria Petiolata//. The genus name //Alliaria// refers to the garlic fragrance of the crushed leaves (//Allium//‑like), which is an unusual odor for the mustard family. The species name //petiolata// refers to the petiolate leaves in the Garlic Mustard plant. GARLIC MUSTARD is the most widely and essentially the only common name used in North America. Additional common names, used primarily in England, include Hedge‑garlic, Sauce‑alone, Jack‑by‑the‑Hedge, and Poor‑man's‑mustard, and less frequently Jack‑in‑the‑Bush, Garlic Root, Garlicwort, and Mustard‑root
 * __ Scientific __**** __Name__ - **// Alliaria Petiolata //
 * __ Common Names __**

Garlic Mustard is a biennial herb of the mustard family. This means that a Garlic Mustard plant will take two full years to fully grow into a mature plant. Seedlings emerge in spring and form basal rosettes by midsummer. Immature plants remain over winter as basal rosettes. In the spring of the second year the rosettes (now adult plants) produce flower stalks, set seed, and subsequently dry up and die. Basal leaves (rosettes) are dark‑green and kidney‑shaped with “scalloped” edges, and range 6‑10 cm diameter. Stem leaves are alternate, triangular or deltoid, and average from a range of 3‑8 cm long and wide. These leaves gradually reduce in size towards the top of the stem. All leaves have something called pubescent petioles which are 1‑5+ cm long. When crushed, new leaves produce a distinct garlic odor. The fragrance fades as leaves age, and is virtually non‑existent by fall. Plants usually produce a single unbranched or few‑branched flower stalk. (However, some extremely rare, robust plants have been recorded with up to 12 separate flowering stalks). Flowers are produced in spring (usually April to May). Flowers are typical of the mustard family, consisting of four white petals (that narrow at the base), and 6 stamens, two short and four long. Flowers average 6‑7mm in diameter, with petals about 3‑6mm long. Individual plants produce an average of 4-16 of something called siliques: Siliques contain an average of 10-20 seeds. Seeds are black and cylindrical and range in weight from 1.62‑2.84mg. At the time of flowering, adult plants range in height from 0.05m to 1.9m, and average 1.0m. An interesting detail is that immature plants can be easily confused with other rosette-forming species, especially violets. However, //Garlic Mustard// can be distinguished from these plants by the classic strong garlic odor in spring and summer. If you wanted to distinguish between similar looking plants and the Garlic Mustard plant in fall and winter, you’d have to look at the root system of the Garlic Mustard Plant. By examining the root system, you can easily identify the Garlic Mustard Plant. //Garlic Mustard// has a white and willowy taproot with a distinctive "s" curve at the top of the root.
 * __ Description and Characteristics __**

Garlic Mustard invades forested communities and edge habitats. The plant //has no known natural enemies in North America// and is self-fertile., Unfortunately, Garlic Mustard plants are extremely difficult to get rid of once they are established. Therefore, the //real// most effective control method for //Garlic Mustard// is to prevent its initial establishment. In communities that do not have an abundance of Garlic Mustard plants, the preferred method is to monitor annually and remove all Garlic Mustard plants prior to seed production. Once the plant is established, the ultimate management goal is to prevent seed production until the seed bank is depleted, which is usually 2 years. Removing of Garlic Mustard plants by pulling them out of the ground from their roots can be effective in areas with minor infestations of Garlic Mustard. This is due to the fact that when plants are removed mechanically by the roots, the soil in the area around the plants becomes disturbed. In minor infestations, this is nothing to worry about. However, in areas heavily populated with Garlic Mustard Plants, seeds from seasonal plants and plants from past seasons are constantly being dispersed; it is common for Garlic Mustard Plants to “pop” seeds out and disperse into the environment. Therefore, disturbing soil in areas with large infestations of Garlic Mustard plants would allow seeds currently laying on the surface of the ground to grow. Essentially, pulling out Garlic Mustard plants mechanically in areas of high infestation would only add to the problem by allowing //even more// plants to grow. Cutting of flowering stems at ground level provides the most effective control with minimal or no side effects. Unfortunately, this method has a high labor cost. Controlling Garlic Mustard through burning and herbicide applications can provide control at a lower labor cost, but each method has potential drawbacks. Fire may alter ground‑layer composition (and could even possibly increase the amount of Garlic Mustard in an area) while herbicides can negatively impact native ground‑layer species. The method of choice depends on the size of infestation, the type of community that is being invaded, and the work‑force that’s available. Unfortunately, once Garlic Mustard is established, successful control is unlikely without considerable amounts of labor and money put forth over an extended period of time. It is important to note that biological control for this species is currently in development. Garlic Mustard is one of the few //alien herbaceous species// that invades and dominates the forested areas in North America In 1997, a field experiment found that removing garlic mustard resulted in greater relative cover of annual species. Another 8-year monitoring study in Illinois showed that in areas with garlic mustard, cover of native perennial herbaceous species declined significantly. Still, the richness of species did not change. Species richness refers to the number of species in a given area. Garlic mustard has been thought to threaten some butterfly species. Adults of several native butterfly species lay eggs on garlic mustard, but many or all of the larvae (which are resting on the Garlic Mustard plants) die before completing development. Thus, garlic mustard serves as a population deterrent for these species. This is a huge cause for concern with the rare West Virginia White Butterfly. This species often lays eggs on garlic mustard in the when the related native host plant, //Dentaria,// is absent. Garlic Mustard is known to be the most widespread in the Midwestern and Northeastern United States and in Southern Ontario. Canada lists Garlic Mustard as one of four principal invasive aliens in upland while Vermont ranks Garlic Mustard as a category 1 species (“highly invasive”). Conversely, Minnesota ranks Garlic Mustard as a "moderate" threat. One of the largest threats of Garlic Mustard is that it appears to alter habitat suitability for native birds, mammals, and amphibians. Although no studies have been conducted about the interaction between Garlic Mustard and certain native animals, scientists believe that Garlic Mustard may affect populations of these species. Once Garlic Mustard is established in a natural area, efforts should be made to eradicate (or at least to contain) the plant and not just monitor its spread.
 * __ Monitoring and Controlling __**
 * __ Threats Posed By Garlic Mustard __**

= **Materials** = · Four standard meter sticks · Magellan Explorer 400 GPS · Two pairs of weed clippers · Plastic bags =** Methods **=
 * Step 1: Using a Magellan Explorer 400 GPS device, the exact coordinates of three separate areas where garlic mustard is grown were measured. The first plot was located at 40°52.427 N, 073°57.926 W. The second plot was located at 40°52.351 N, 073°58.004 W. The third plot was located at 40°52.425 N, 073°57.965 W.
 * Step 2: Four standard meter sticks were taped together tom make 1 square meter.
 * In each of the three locations, the square was dropped into the Garlic Mustard. Then, using flags, the perimeter of the square meter that is measured was marked off.
 * Step 3: In the first plot, stems were cut approximately one inch from the ground. While doing this, the number of stems that had been cut were counted and recorded.
 * Step 5: In the second plot, the stems were cut right below the branches and flowers. Again, the number of stems that had been cut were counted and recorded. (note: when finished, stems were approximately six to nine inches from the ground)
 * Step 6: The third plot was left as a control site. In this spot, the number of stems were counted and measured. This was the initial height.
 * Step 7: After four days, results were checked. In each plot, approximately 1/3 of the stems were measured and subtracted from that of their initial height. This number showed how much the Garlic Mustard had grown in each spot over the given period of time. The growth rate of each stem was recorded and that number was rounded up to the nearest 0.5 decimal.
 * Step 8: After eight days, Step seven was repeated
 * Step 9: Results were recorded.

= **Results** = = = Approximate Number of Weeds: 85
 * __Location__ 1**: 40°52.427 N, 073°57.926 W

(the chart/graph depicts 1/3 of the approximate number of weeds)

Table: Graph 1:
 * Total Number of Garlic Mustard || Days || Growth rate of 2.0 in. || Growth rate of 2.5 in. || Growth rate of 3.0 in. || Growth rate of 3.5 in. || Growth Rate of 4.0 in. ||
 * 28 || 4 days || 17 || 9 || 2 || 0 || 0 ||
 * || 8 days || 10 || 8 || 5 || 4 || 1 ||

__**Location 2**__: 40°52.351 N, 073°58.004 W
Approximate Number of Weeds: 67 (the chart/graph depicts 1/3 of the approximate number of weeds)

Table 2: Mustard || Days || Growth rate of 0.5 in. || Growth rate of 1.0 in. || Growth rate of 1.5 in. || Growth rate of 2.0 in. || || 4 days || 8 || 9 || 4 || 1 || Graph 2:
 * Total Number of Garlic
 * 22
 * || 8 days || 3 || 5 || 7 || 7 ||

Location 3: 40°52.425 N, 073°57.965 W Approximate Number of Weeds: 72

(the chart/graph depicts 1/3 of the approximate number of weeds)

Table 3: Graph 3:
 * Total Number of Garlic Mustard || Days || Growth rate of 0.5 in. || Growth rate of 1.0 in. ||
 * 24 || 4 days || 24 || 0 ||
 * || 8 days || 19 || 5 ||

This final graph compares the growth of all three plots of Garlic Mustard plants. It is clear that the taller a plant grows, the less rapidly it grows. Still, while the plot we cut low to the ground grew back the most rapidly, it only grew enough to formulate leaves, and it would take much longer for the plants to germinate. While the plot we cut from below the flowers grew back at a less rapid rate, it was still enough to allow more flowers to germinate. Knowing this, we can infer that the most efficient way to control Garlic Mustard is to cut the plant close to the ground as late in the spring as possible.

= **Discussion** =

In location 1, each stem was cut approximately one inch from the ground. As seen in table one and graph one, four days after our initial experiment, we noticed viable changes. Using a meter stick to measure approximately 1/3 of the 85 stems that we cut, we noticed that the stems had grown back anywhere from 2 to 3.5 inches. Of the 28 stems that we measured, we noticed that most of the garlic mustard only grew between 2 to 2.5 inches. In addition, we noticed that no new leaves or flowers had grown back yet. However, when we revisited the site four days later, we saw more change. We noticed that although the majority of leaves didn’t grow more than 2.5 inches, a few grew to be 3.5 to 4 inches. We also noticed that leaves grew back in only a few of the stems; however, no new flowers had grown. Our graph shows the range of growth that took place (we rounded the growth to the nearest 0.5 inches and grouped them as follows). In location 2, each stem was cut towards the top right bellow the seedpods/branches. As seen in table 2 and graph 2, after four days, we noticed less change than we did in that of the first location. Most of the 22 stems that we measured grew back no more than one inch. We did notice that new leaves and branches had formed; however, flowers had not bloomed yet. After eight days, we noticed more significant changes. The majority of the stems had grown 1.5 to 2 inches. In addition, we noticed that new leaves had grown and in many of the Garlic Mustard and new flowers began to bloom. Our graph shows the range of growth that occurred (we rounded the growth to the nearest 0.5 inches and grouped them as follows). In our control site, we noticed completely different results. As seen in table 3 and graph 3, after four days, we noticed that all of the 24 Garlic Mustard that we had initially measured grew only 0.5 inches from its original height that we measured on the day we first established the experiment. Most of the flowers were dead or close to it, and the leaves and stems were still fully grown. When we came back after eight days, we noticed that much had still not changed. A few of the plants grew about an inch, however, the majority still didn’t grow over 0.5 inches. No new changes were seen in either the leaves or stems. The only significant change that we saw was that all of the flowers had died, which proves that it is the end of Garlic Mustard season. Although it is a biennial herb and therefore always shows up, it is no longer going to grow until next fall. This decline in growth rate justifies a significant portion of our conclusion.

= **Conclusion** =

After recording the final results of our experiment and engaging in an in-depth conversation with Ranger Mark, our group came to the conclusion that the most effective way to control and reduce the infestation of Garlic Mustard plants in a given area would be through the method of cutting the plants at the very bottom of their stems. What’s more, it is important that this cutting be done in late spring (May or June), when the Garlic Mustard plant is nearing the end of its lifespan and therefore producing few (if any) more flowers/seeds. By monitoring our control site over a period of time in late spring, we noticed that no new flowers grew on it. Because no new flowers (or few) are blooming at this time of year, no more seeds are being produced which could potentially be dispersed. By cutting the plants from the bottom of the stem late in the season, you are eliminating the possibility that the plant will grow back enough to germinate and disperse seeds. In the plot that we cut, the only significant change over time that we observed was that the stem grew no higher than 4 inches. In fact, the majority of them had only grown up to 3 inches. In addition, cutting them this low on the stem only allowed leaves (NOT flowers) to grow back in certain cases. It would take //much// more time for these plants to create new seeds, and they’d die before they’d get to that point. This isn’t even taking into consideration the fact that cutting the plant at the bottom of the stem severely reduces its photosynthetic capabilities. In the plot that we cut just below the branches/seedpods (significantly higher up on the plant) new flowers began to form in 8 days. This shows that this method isn’t very effective in reducing the amount of Garlic Mustard plants, as new seeds //still// have the potential to be dispersed into the environment, even this late in the season. Overall, the results of our experiment unmistakably point to cutting the plant toward the bottom of the stem as being the most effective way of limiting Garlic Mustard. By doing this //late in the season//, the plants will not have enough time to re-germinate, and will soon die. Indeed, our hypothesis was correct! Looking back on the experiment, while our results showed us the most effective method, this method is extremely labor intensive, especially if we want //truly// reduce the amount of Garlic Mustard plants in the environment. Thus, we face a severe struggle in limiting Garlic Mustard, one that unfortunately isn’t entirely feasible. Still, we can do our best to control it, which we think our method can do. Without question, it would be immensely effective to have volunteer groups of large numbers gather at the end of every season to do what we just did. Still, our group believes it is necessary to spread awareness of problems such as this particular invasive species. = **Pictures** =

The first picture is the plot just after we cut it from the stem 1 inch from ground. In the next picture, taken 8 Days later, we can see that only leaves have grown (no flowers) and the stem has grown 2-4 inches longer.

The first picture here is of our plot just after we cut the stems right below the seedpods/branches. The next picture is a close up image of a plant from the same plot 8 days later. We can see that this was enough to allow flowers to re-formulate on the plants

This is a picture of our control plot before and after the 8 day period

= **Bibliography** =

"Garlic Mustard (Alliaria Petiolata)." __Wisconsin Department of Natural Resources__. 24 May 2008 <[|http://dnr.wi.gov/invasives/fact/garlic.htm>.] "Garlic Mustard Identification and Control." __Invasive Plants Association of Wisconsin__. 25 May 2008 <[|http://www.ipaw.org/invaders/garlic_mustard/gm.htm>.] "Invasive Species- Plants: Garlic Mustard." __National Invasive Species Information Center__. 26 May 2008 <[|http://www.invasivespeciesinfo.gov/plants/garlicmustard.shtml>.] "Species Richness." __Encyclopedia of Earth__. 25 May 2008 <[|http://www.eoearth.org/article/Species_richness>.] "TNC Global Invasive Species Team Page." __The Nature Conservancy__. 22 May 2008 <[|http://tncweeds.ucdavis.edu/alert/alrtalli.html>.]