PTIONS O MPACT ACTORS individual by hand once the flow- the hand once by plants individual I F Overwintering rosettes tend to shade out shade to tend rosettes Overwintering other native plants. native other thistles, many Like Italian thistle displaces forage plants and plants forage displaces thistle Italian EY Resprouts from root portions left in the soil if crown. root below cut not of a lot have you help,con- to Unless volunteers methods hand by thistle Italian trolling (pulling, digging, cutting) be may feasible only for small infestations.Digging is reported to be thistle, killing Italian at effective will cause but considerable soil disturbance, often resulting recolonization. or in seed germination Pull are flowers before but bolted have ering stems produced. Spines necessitate the use of necessitate Spines when gloves working on this . Ver y high seed produc 10 years. to Seed up longevity t ion. High germination rate. reduces the value of value the reduces grazing land. spines The REATMENT are unpalatableare to most animals. u T u u K u u u u WEED WORKERS’ HANDBOOK WEED WORKERS’ Italian thistle reproduces only by seed. by only reproduces thistle Inner Italian Italian thistle is a winter thistle Italian ESCRIPTION EPRODUCTION (disk) seeds are cream-colored, seeds are (disk) first, at sticky striped, bristles. have and seeds are (ray) Outer yellowish to brown, smooth, and have no bris- tles. and wind-dispersed seeds are disk Most feet. hundred several can travel seeds also Disk coating, a thin gummy have them allows which to attach to animals and machinery. The germi- nation is rate high, and germination typically fall. in the place takes seeds generally Ray drops. it until head flower in the remain These 10 years. to up for soil in the seeds persist R December, to September From to pink in com- bloom flowers white) rarely (but purple borne terminally in inflorescences posite ofclusters 2–5. inflorescences thistle Italian across, a half-inch only measure than smaller ofthose thistle. artichoke or bull Italian thistle is commonly found on found is commonly thistle Italian disturbed sites, grasslands, annual pastures, riparian and areas. Drought- stressed, overgrazed, and frequently vulnerable to more are disturbed sites invasion. thistle Italian broadleaf biennial or annual tallplant. and 1–6 feet grows It has erect, stems. spiny-winged lanceolate, are The leaves 6 to up long,inches pinnately and divided, the tip of at with a spine at spine largest the lobe and each tip ofthe leaf.The the leaf and stems down. a cobwebby have undersides D Also known as slender thistle slender as known Also pycnocephalus () Family Sunflower ITALIAN THISTLE ITALIAN

ANNUALS 82 u Dig the plants out with a pick or shovel. DISPOSAL u Cut just below the crown with a small pick or Seed heads should be removed from the site and trowel. This is a useful option in summer bagged or burned.The stems can be composted. when the ground is too hard for pulling stems by hand. FOLLOW-UP u Brush cut or weed whip before the thistles Whichever treatment you choose, return to the begin to flower. Repeat the treatment into site at least twice a year for a period of several early summer to ensure energy reserves have years to monitor seedling growth and prevent been reduced. further seed production. u Graze. and will graze on thistles, INTERESTING FACTS especially in the early spring when they have Native to the Mediterranean, Italian thistle reached 4–6 inches in height. Graze the ani- appeared in in the 1930s, but it is not mals for roughly 2–3 weeks in large numbers. clear how it was introduced. u Foliar spray. Some practitioners apply to the plants before they go to seed, generally around mid-spring.

Notes ANNUALS

THE PLANTS: HOW TO REMOVE BAY AREA WEEDS 83