Canada Thistle

CANADA THISTLE

(Creeping thistle, field thistle)

Habitat: Cultivated fields, meadows, pastures and roadsides.

Description: Canada Thistle is a perennial that reproduces by seed and freely sprouting from the roots which can be 15 - 30 cm deep.  The stems are erect, hollow and branch at the top.  They are .3 - 1.2 meters in height.  The oblong leaves alternate and are irregularly cut into segments with sharp spoines on the tips.  Flowers can be purple or white.  Males flowers do not produce seeds.  The seeds from the female flower are tan in color, slightly curved with white hairs lightly attached.

Control Practices: There are a few ways for controlling Canada Thistle.  They are as follows:

1. Cultivation will starve the root system if done properly.  Tillage should be done after harvest with a cultivator.  In the spring, early tillage continued until freeze-up is recommended.  Not allowing the green growth remail above ground for more than a week.  Tillage can also be done instead when the thistle has reached the early bud stage.  The plant is the weakest at that point.  Tillage should continue until freeze-up.  Working summerfallow can also be very effective.

2. Seedlings are sensitive to competition and do not grow well in shade.  Shading can be provided by seeding alfalfa or brome.  Cut the hay crop twice a year with out grazing.  Grain crops can also provide the needed shading.  Use adequate fertilizer to allow the crop to get an early start before the thistle starts growing.  Fall rye and spring barley are great competitors.  Harvest the grain as early as possible and continue tillage until freeze-up.

3. Oats can be grown as green feed.  Tillage should be done for the rest of the season.

4. Chemical application is also an option.

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