Shepherd's purse
Name: Shepherd's purse
( case-weed, lady )
Latin name: Capsella bursa-pastoris L. (C. simplex, Bursa bursa-pastoris)
Occurrence: Shepherd
Biology: Flowering and fruiting occur throughout the year but are most frequent from May to October. There are 10-12 seeds per capsule and an average of 4,500 seeds per plant, although much higher numbers have been recorded. Seed size varies considerably both within and between populations. Plants growing in adverse conditions produce fewer but larger seeds. Flower spikes cut prematurely produce viable seeds from the large unripe seed capsules but not from smaller fruits.
Seeds from both dead-ripe and green capsules require a period of after-ripening before they will germinate. A period of stratification followed by exposure to light is needed to relieve dormancy and promote germination. The temperature during after-ripening can affect the temperatures at which seeds will germinate.
Shepherd
Persistence and Spread: Seed buried in soil can remain viable for 35 years or longer. In a succession of autumn crops over a 3-4 year period, in fields ploughed annually, the annual decline of shepherd
Management: Control is by repeated surface tillage, and by the cultivations normally used in root crops to deal with tap-rooted weeds. Fewer seedlings emerge from a seedbed with larger clods of soil than from a fine seedbed. It is important to prevent flowering and seeding. The introduction of seeds in manure or contaminated crop seed should be guarded against too.
Stubble cleaning can be an effective way of reducing seed numbers in soil. The surface soil is cultivated to a depth of 5 cm at 14-day intervals. Fallowing has little effect on seed numbers in soil in the short or the long term. In reduced tillage systems seed numbers increase in the upper 15 cm of soil.
Seedlings with 2-6 leaves are tolerant of flame weeding. Shepherd
Further Information / Links:
For more information on this weed
- Fully referenced review Shepherds purse (118 Kb) October 07
»UK farmers' case studies
» For more pictures and information
» A picture of a Shepherd's Purse seedling at the SAC crop clinic
« Back to Annual Broad-leaved Weeds
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Comments
- Lizzie Tatro 5---0-2007
You state that each capsule purse can contain 10 to 12 seeds and then that plant can produce 4500 seeds. That makes 400 purses for each plant. Is that really so? The plants around here might be lucky to have 40 purses. I note that in your extened version - the fully referenced review - estimates of seeds per plant vary enormously from 2000 to 90,000. I would have thought the Oregon State University info in 'more pictures and information' was nearer the mark with 1000 seeds per plant and they show a dense multi stemmed plant compared to the slim meagre example above.
Does it all matter that much? Am I just being a pedantic bore? Or is it asll just a bit of fun? Perhaps, at least, you could include a little warning that all these widely varying statistics need to be taken with a hefty dollop of salt.
- William Edmonds 3---0-2008
Ploughing reduces the population considerably versus conservation tillage.
Another management advantage is to produce a full stand of alfalfa seedlings rapidly.
For sloping fields that should not have the plough it is a real challenge.
- Allan Spicer 1---1-2008