Source: California Invasive Plant Council
URL of this page: http://www.cal-ipc.org/ip/management/ipcw/pages/detailreport.cfm@usernumber=88&surveynumber=182.php
Invasive Plants of California's Wildland
|Scientific name||Vinca major|
|Additional name information:||L.|
|Common name||periwinkle, bigleaf periwinkle|
|Synonymous scientific names||none known|
|Closely related California natives||0|
|Closely related California non-natives:||0|
|Listed||CalEPPC List B,CDFA nl|
HOW DO I RECOGNIZE IT?
Apocynaceae. Stems: non-flowering stems prostrate; flowering stems erect to 0.5-1.5 ft (15-45 cm). Leaves: to 2-3 in (5-7.5 cm) long, covered with a waxy cuticle, cordate at base, tapering to acute apex. Leaves opposite, 4-ranked; entire margins covered by ciliate hairs (Bean and Russo 1986). Petioles nearly glabrous, <1 in (2.5 cm) long. Flowers: rotate, 1-2 in (2.5-5 cm), with fused, 5-part calyx. The 5 stamens distinctively curve at the base and are arranged alternate to corolla lobes. There are 2 superior ovaries, which may be sterile, but if seeds are present they are curved and hairy (Hickman 1993).
|WHERE WOULD I FIND IT?||
Periwinkle’s range extends from California throughout the southern United States. In California it is found up to 610 feet (200 m) elevation in most coastal counties, the Central Valley, and desert areas. It prefers a mediterranean climate and frost-free, damp, shaded soils (Stern 1973). It has been observed thriving along tree-covered drainages and creeks in coastal areas (Alvarez 1997). It has escaped from gardens and old homesteads where it has been used as an ornamental groundcover and is commonly found spreading from moist roadside locations where it has been dumped (Bean and Russo 1986).
|WHERE DID IT COME FROM AND HOW IS IT SPREAD?||
Originally from southern Europe and northern Africa, periwinkle was introduced to the United States as an ornamental groundcover and medicinal herb (Schittler 1973). It spreads vegetatively and is not known to reproduce sexually in California (Bean and Russo 1986). Water can transport broken stem fragments throughout riparian zones, where the plant’s ability to resprout enables it to spread rapidly. The rate of spread is not documented in the literature, but it appears to be limited by shade and moisture requirements.
|WHAT PROBLEMS DOES IT CAUSE?||
Once established, periwinkle forms a dense cover that prevents growth and establishment of other plant species (Stern 1973). Periwinkle lowers species diversity and disrupts native plant communities. Riparian zones are particularly sensitive. Major infestations at The Nature Conservancy’s Ramsey Canyon Preserve in southern Arizona have suppressed natural erosional processes in a creek, promoting deepening and scouring of the creek bed and altering local hydrology and vegetation (McKnight 1993).
|HOW DOES IT GROW AND REPRODUCE?||
(click on photos to view larger image)
Manual/mechanical methods: Hand removal is labor-intensive, but yields good results if careful attention is paid to removing all root nodes and stolons. In Ramsey Canyon, Arizona, volunteers successfully cleared four acres using hand removal over a three-year period. An effective method is to work inward from the perimeter of the patch and pull the periwinkle back in on itself to prevent further spread of the weed between removal sessions (TNC 1997). Repeated removal efforts, scheduled over a growing season, may allow natives to recolonize the area and reduce the chance that other weeds will move into the area following the disturbance caused by removal activities (Mcknight 1993).
Because periwinkle has the ability to resprout, mowing or cutting results in abundant regrowth and is not recommended (TNC 1997).
Biocontrol agents have not been determined or tested for Vinca major.
Glyphosate (as Round up®) has been tested on large infestations of periwinkle at Ramsey Canyon, Arizona. Greatest success is achieved if plants are cut first and then sprayed immediately afterward. Cutting with a weed whip or brush cutter breaks through the waxy cuticle and allows better foliar penetration of the herbicide. Using the cut and spray method, a 5 percent glyphosate solution gave nearly 100 percent control. To reduce native plant death in the area, a 3 percent solution provides 70-75 percent control and yields good results if followed by spot applications (Bean and Russo 1986). A wick applicator is suggested for spot treatments, and a backpack sprayer is recommended for treating large areas. To aid chemical distribution throughout the plant, use surfactant and apply herbicide during an optimal growing period of good moisture and warm temperatures (70-80 degrees F) usually in late spring or early fall.
Monitoring is recommended. Follow-up on any removal actions is necessary, as any overlooked stem or plant fragments will quickly resprout. Following chemical removal, the population should be checked twice, in early fall and late spring. With manual removal, follow-up should be performed every three months to remove resprouts. After the patch is eradicated it should be checked twice a year in optimal growing seasons.