MANAGEMENT OF A3924-30 Leafy spurge (Euphorbia esula) INVASIVE PLANTS IN WISCONSIN earfy spurge is an herbaceous, Ecological threat: creeping perennial, 6–36” tall. • Invades grasslands, pastures, prairies, Brendon Panke, Ryan deRegnier, LStems are smooth and often grow and old fields. and Mark Renz in clusters from an extensive, deep root • Can drastically reduce (50–75%) system. A white, milky latex is present in all productivity of grasslands. parts of the plant. Legal classification in Wisconsin: nvasive plants can thrive Restricted Non-chemical control and aggressively spread Leaves: Leaves are linear, alternate, and Removal I have slightly wavy, smooth margins with Effectiveness in season: 50–70% a bluish green color. Leaves are 0.25–0.5” beyond their natural range, Season after treatment: < 50% wide and 1–4” long. disrupting ecosystems. The Pulling is only appropriate for suppression Flowers: Late spring to summer. The of very small populations or populations in flowers are small, green, and are borne Management of Invasive Plants their first year of growth. Older populations in clustered yellow-green bracts. These do not respond well to pulling because it in Wisconsin series explains how bracts develop in late spring, and the is difficult to remove the entire root. If the flowers develop within the bracts by to identify invasive plants and root is not removed, it will resprout. early summer. provides common management Fruits and seeds: Seeds are 0.08” long, Cultivation options. Management methods oblong, gray to purple, and are borne in pods which contain three seeds. When Effectiveness in season: 50–70% recommend specific timings mature, seed capsules shatter, scattering Season after treatment: < 50% seeds. Intensive cultivation can eradicate for treatment, as well as Roots: Brown, woody roots with pinkish populations. Cultivate 4” deep 2–4 weeks expected effectiveness. For more buds. Plants have a taproot, which may after leafy spurge emerges in the spring; extend to the water table, and lateral for 1–2 years, continue to cultivate at three- information, go to: roots that can extend to 15’ beyond the week intervals until the ground freezes. main taproot. Success has also been documented if leafy fyi.uwex.edu/weedsci/category/ spurge is cultivated twice each fall for three Similar species: A number of native years. Cultivation can spread roots into invasive-plants-of-wisconsin. species also have white, milky sap previously uninfested areas. (e.g., milkweed species and flowering spurge), but milkweed species have a distinct long seedpod, and flowering spurge is distinguished by white flowers. Cypress spurge (Euphorbia cyparissias) is another non-native species that is often confused with leafy spurge. Cypress Cooperative Extension spurge has a similar flower, but is a shorter plant (6–15” tall) with needle- NPM like leaves. MANAGEMENT OF INVASIVE PLANTS IN WISCONSIN best long-term control. Do not skip a Mowing Biological control year until control reaches 90% or more; Effectiveness in season: 50–70% Effectiveness in season: < 50% otherwise leafy spurge will reinfest rapidly. Season after treatment: < 50% Season after treatment: < 50% Mowing does not eradicate leafy spurge, The three commonly recommended 2,4-D* but if repeated at 2–4-week intervals agents for biological control of leafy Effectiveness in season: 50–70% during the growing season, it can suppress spurge are Aphthona nigriscutis, A. Season after treatment: < 50% populations and reduce seed production. lacertosa, and A. czwalinae. The larvae of Common name: Many Mowing can also provide uniform these agents are root borers and feed on regrowth, which can improve herbicide foliage as adults. Grazing in conjunction Rate: effectiveness. After mowing, populations with biological control has been shown broadcast: 1.0–1.5 lb a.e./A should be allowed to grow for 3–5 weeks to be very effective. This combination spot: For a 3.8 lb a.e./gal product. 1–2% before an herbicide is applied. of methods typically takes 4–5 years to (0.04–0.08 lb a.e./gal) reduce leafy spurge cover to < 10%. To Timing: Apply twice a year: once during Prescribed burning release biocontrol agents in your state, late bud stage when bracts begin contact the Department of Agriculture for to yellow and again in the fall when Effectiveness in season: 50–70% the required permit. regrowth is 4–6” tall. Season after treatment: < 50% Remarks: This herbicide will not eliminate Spring burns can kill germinating seedlings Manipulation of the a population when used as the only and suppress above-ground growth of control method, but it can be useful established plants, depending on fire environment when paired with other control intensity. Fire may benefit other species Effectiveness in season: < 50% methods. The use of 2,4-D in the spring well-adapted to this management (e.g., Season after treatment: < 50% will eliminate the production of seed. prairie grasses), resulting in improved Interseeding with competitive grass can competition with leafy spurge. A handheld Caution: Use aquatically labeled product suppress leafy spurge populations up to propane torch can be effective for treating if potential exists for solution to contact 80% once the grasses become established. seedlings. A combination of burning and surface water. Use of this chemical This treatment will rarely eliminate herbicide applications typically takes 4–5 in areas where soils are permeable, leafy spurge; therefore, integrating this years to provide > 95% suppression of a particularly where the water table is method with another control method is leafy spurge population. shallow, may result in groundwater recommended. contamination. Overspray or drift to Grazing desirable plants should be avoided since Chemical control even minute quantities of the spray may Effectiveness in season: < 50% cause severe injury to plants. Season after treatment: < 50% Foliar Grazing with sheep or goats can be used Apply directly to individual plants aminocyclopyrachlor + chlorsulfuron* to suppress populations. Grazing when or broadcast across an infested area. Effectiveness in season: 90–100% bracts are present, but before seeds Broadcasted foliar applications are typically Season after treatment: 70–90% are produced, has shown the greatest the most-cost effective treatment in dense reduction in spurge biomass. If mature infestations. Use lower rates on smaller Common name: Perspective seeds are consumed, animals must be plants and less dense populations and Rate: isolated until the seeds pass through the higher rates on larger plants and denser broadcast: 4.75–8.0 oz/A digestive system to prevent further spread populations. Absorption of herbicide can (aminocyclopyrachlor: 1.9–3.15 oz a.i./A of seed. Grazing in conjunction with a fall be limited with this species, resulting + chlorsulfuron: 0.75–1.25 oz a.i./A) chemical treatment is very effective. This in reduced effectiveness. Including a spot: 0.2–0.3 oz/gal combination of methods typically takes recommended surfactant can alleviate any (aminocyclopyrachlor: 0.08–0.12 oz a.i./ 4–5 years to provide > 95% suppression of potential reduction in effectiveness. When gal + chlorsulfuron: 0.03–0.05 oz a.i./gal) a leafy spurge population. using residual herbicides (e.g., picloram, Timing: Apply to flowering plants or in fall aminocyclopyachlor), treat 15’ outside the before a killing frost. Fall applications edge of a population to reduce resprouting show the most consistent results. from roots in subsequent years. No single treatment will eradicate this plant. An annual treatment program provides the *Active ingredient (a.i.) 2 LEAFY SPURGE Caution: Do not apply directly to water avoided since even minute quantities desirable plants should be avoided since or to areas where surface water is of the spray may cause severe injury to even minute quantities of the spray may present. Avoid using Perspective in areas plants. Do not compost treated plants cause severe injury to plants. where soils are permeable, particularly since herbicide can persist through where the water table is shallow, since composting process. imazapic* groundwater contamination may result. Effectiveness in season: 90–100% Perspective remains in the soil for dicamba* Season after treatment: 50–70% months, depending on application rate, Effectiveness in season: 50–70% and has the potential to contaminate Common name: Plateau Season after treatment: < 50% surface runoff water, especially on Rate: poorly draining soils or areas with Common name: Banvel broadcast: 6–12 fl oz/A shallow groundwater. Maintenance of a Rate: (0.1–0.2 lb a.e./A) vegetative buffer strip is recommended broadcast: 64–128 fl oz/A (2–4 lb a.e./A) spot: 0.25–1.0% (0.005–0.02 lb a.e./gal) between the areas Perspective is spot: Equivalent to broadcast rates. Timing: Apply in fall before a killing frost. applied and surface water features. Timing: Apply to flowering plants or in fall Overspray or drift to desirable plants Remarks: Add methylated seed oil (MSO) before a killing frost. Fall applications should be avoided since even minute to the mixture as per label instructions. show the most consistent results. quantities of the spray may cause severe Caution: Do not apply directly to water or injury to plants. Do not compost treated Remarks: Two to three years of repeated to areas where surface water is present. plants since herbicide can persist applications are typically needed. If Use of this chemical in areas where through composting process. repeated, this treatment can achieve soils are permeable, particularly where more than 80% suppression. the water table is shallow, may result in aminocyclopyrachlor + metsulfuron* Caution: Do not apply directly to water or groundwater contamination. Imazapic to areas where surface water is present. can remain in the soil for months, Effectiveness in season: 90–100% Use of this chemical in areas where depending on application rate, and has Season after treatment: 70–90%% soils are permeable, particularly where the potential to contaminate surface Common name: Streamline the water table is shallow, may result in runoff water during this timeframe.