Posted on

common weed seed size

Weed Seed: Ambrosia artemisiifolia (Common ragweed)

Secondary Noxious, Class 3 in the Canadian Weed Seeds Order, 2016 under the Seeds Act.

Distribution

Canadian: Occurs across Canada except in NU and YT (Brouillet et al. 2016 Footnote 1 ).

Worldwide: Native to North and South America, and widely introduced elsewhere including Europe, Africa, temperate and tropical Asia, Australasia and the Pacific Islands (USDA -ARS 2016 Footnote 2 ). Widely distributed in North America with both native and introduced populations present in the U.S. and Canada (Brouillet et al. 2016 Footnote 1 , USDA -NRCS 2016 Footnote 3 ).

Duration of life cycle

Seed or fruit type

Achene within a bur

Identification features

  • Bur length: 1.9 – 3.7 mm
  • Bur width: 1.5 – 2.8 mm
  • Achene length: 1.5 – 3.0 mm
  • Achene width: 1.5 mm

Shape

  • Bur and achene are obovate

Surface Texture

  • Bur is dull, woody

Colour

  • Bur is dark grey with purple streaks
  • Achene is brown

Other Features

  • Bur has a ring of several spines near top approximately 0.5 mm long and an apical spine approximately 1.5 mm long

Habitat and Crop Association

Cultivated fields, fencerows, pastures, shores, canals, quarries, railway lines, roadsides, wasteland and disturbed areas (FNA 1993+ Footnote 4 , Darbyshire 2003 Footnote 5 , CABI 2016 Footnote 6 ). Found in a range of both agronomic and horticultural crops, particularly in cereals and cultivated row crops (Basset and Crompton 1975 Footnote 7 , CABI 2016 Footnote 6 ). Often present as a dominant species in early succession of uncultivated areas (CABI 2016 Footnote 6 ).

General Information

Seeds of common ragweed are commonly found in stored and transported grains, and have been dispersed around the world as contaminants in seed and grain crops, including cereals, oilseeds and bird seed.

A single plant typically produces 3,000 – 4000 seeds, although up to 32,000 seeds per plant have been reported. Seeds remain viable for up to 40 years (CABI 2016 Footnote 6 ).

Similar species

Perennial ragweed (Ambrosia psilostachya)

  • Perennial ragweed burs are a similar size, obovate shape and grey colour as common ragweed.
  • Perennial ragweed burs have smaller spines, or only an apical spine that may be broken off, and may lack the purple streaks of common ragweed burs.
  • If the burs are removed, it is difficult to distinguish between common and perennial ragweed achenes.

Photos

Similar species

Footnotes

Brouillet, L., Coursol, F., Favreau, M. and Anions, M. 2016. VASCAN, the database vascular plants of Canada, http://data.canadensys.net/vascan/ [2016, May 30].

Darbyshire, S. J. 2003. Inventory of Canadian Agricultural Weeds. Agriculture and Agri-Food Canada, Research Branch. Ottawa, ON .

Bassett, I. J. and Crompton, C. W. 1975. The biology of Canadian weeds. 11. Ambrosia artemisiifolia L. and A. psilostachya DC. Canadian Journal of Plant Science 55: 463-476.

Weed characteristics

Knowing what weeds are common on a particular farm will help to determine what lessons can be learned and what management strategies might be effective against them. What can we learn about common weeds to help with weed management?

Background

Most weeds have some characteristics in common. Weeds generally produce large numbers of seeds. Weed seeds can often germinate under a variety of conditions, but some portion of the seed population remains dormant. Dormant weed seeds are insurance against conditions that might destroy growing plants. Even though 95% of the weed seeds in the soil ‘seed bank’ may be lost to germination or death, the seed bank can often recover in a single year. Many weeds develop rapidly, are able to self-pollinate, disperse widely and tolerate a wide range of environmental conditions. A study in 1980 indicated that despite enormous effort, weeds have steadily increased from 1900 to 1980. This trend probably continues.

See also  girl scout cookies weed seeds uk

Weeds have characteristics unique to each species, so recognizing weed species can be important. Many sources are available to help with weed identification.

Several weed characteristics have been summarized in Table 1. Let’s compare wild oats and green foxtail as an example of what we can learn from these characteristics.

Green foxtail (commonly known as wild millet or pigeon grass) is an annual grass with small seeds that birds seem to love. As with most weeds, seed production can be prolific. Seeds that germinate on the soil surface, or in surface chaff, often have trouble rooting, so these species can be less abundant in zero-tillage systems. Root development, even within the soil is not extensive. Therefore, harrowing is often an effective means of control. Green foxtail is a warm season grass. It germinates more quickly and is more competitive at higher temperatures. Thus, it is more aggressive in late-seeded crops, common in organic systems, and is less vigorous in cooler situations such as in zero-till, or early seeding. Mature plants vary in size from one inch to three feet. Large plants can be quite competitive. Small, very dense plants can reduce surface moisture supplies.

Wild oat is an annual cool season grass. It has larger seeds, and thus is less prolific. Because the seeds are large, they tend to dry out on the soil surface, making wild oats more common in wet areas, or low spots. Wild oat germinates quickly in cool soils, and is more competitive at lower temperatures. Thus, it can emerge before the crop and become very competitive. Pre-seeding tillage will remove many early germinating plants. Later seeded crops may be relatively free of wild oats. Wild oats can be quite competitive. Seeds can remain dormant for long periods, making wild oat management a perennial task.

Common weed seed size

Rթ`�U9<� �A#� endstream endobj 39 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 34 0 obj >>/BBox[0 0 612 792]/Length 131>>stream x� �; �0 ��ާ� 6^ǑL˫�B� plGJ�� !nO܌�O� �j. ���`� ���=Y ���1 �J��A޸Ǒp*_�KH9ax� 1�+�Yb

Rթ`�U9<� �A#� endstream endobj 37 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 12 0 obj >>/BBox[0 0 612 792]/Length 131>>stream x� �; �0 ��ާ� 6^ǑL˫�B� plGJ�� !nO܌�O� �j. ���`� ���=Y ���1 �J��A޸Ǒp*_�KH9ax� 1�+�Yb

Rթ`�U9<� �A#� endstream endobj 29 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 11 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 36 0 obj >>/BBox[0 0 612 792]/Length 131>>stream x� �; �0 ��ާ� 6^ǑL˫�B� plGJ�� !nO܌�O� �j. ���`� ���=Y ���1 �J��A޸Ǒp*_�KH9ax� 1�+�Yb

Rթ`�U9<� �A#� endstream endobj 31 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 7 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 20 0 obj >>/BBox[0 0 612 792]/Length 131>>stream x� �; �0 ��ާ� 6^ǑL˫�B� plGJ�� !nO܌�O� �j. ���`� ���=Y ���1 �J��A޸Ǒp*_�KH9ax� 1�+�Yb

See also  united states weed seed banks

Rթ`�U9<� �A#� endstream endobj 17 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 45 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 14 0 obj >>/BBox[0 0 612 792]/Length 131>>stream x� �; �0 ��ާ� 6^ǑL˫�B� plGJ�� !nO܌�O� �j. ���`� ���=Y ���1 �J��A޸Ǒp*_�KH9ax� 1�+�Yb

Rթ`�U9<� �A#� endstream endobj 33 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 10 0 obj >>/BBox[0 0 612 792]/Length 131>>stream x� �; �0 ��ާ� 6^ǑL˫�B� plGJ�� !nO܌�O� �j. ���`� ���=Y ���1 �J��A޸Ǒp*_�KH9ax� 1�+�Yb

Rթ`�U9<� �A#� endstream endobj 25 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 27 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 35 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 41 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 13 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 3 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 26 0 obj >>/BBox[0 0 612 792]/Length 131>>stream x� �; �0 ��ާ� 6^ǑL˫�B� plGJ�� !nO܌�O� �j. ���`� ���=Y ���1 �J��A޸Ǒp*_�KH9ax� 1�+�Yb

Rթ`�U9<� �A#� endstream endobj 5 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 18 0 obj >>/BBox[0 0 612 792]/Length 131>>stream x� �; �0 ��ާ� 6^ǑL˫�B� plGJ�� !nO܌�O� �j. ���`� ���=Y ���1 �J��A޸Ǒp*_�KH9ax� 1�+�Yb

Rթ`�U9<� �A#� endstream endobj 43 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 4 0 obj >>/BBox[0 0 612 792]/Length 131>>stream x� �; �0 ��ާ� 6^ǑL˫�B� plGJ�� !nO܌�O� �j. ���`� ���=Y ���1 �J��A޸Ǒp*_�KH9ax� 1�+�Yb

Rթ`�U9<� �A#� endstream endobj 23 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 15 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 24 0 obj >>/BBox[0 0 612 792]/Length 131>>stream x� �; �0 ��ާ� 6^ǑL˫�B� plGJ�� !nO܌�O� �j. ���`� ���=Y ���1 �J��A޸Ǒp*_�KH9ax� 1�+�Yb

Rթ`�U9<� �A#� endstream endobj 9 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 19 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 38 0 obj >>/BBox[0 0 612 792]/Length 131>>stream x� �; �0 ��ާ� 6^ǑL˫�B� plGJ�� !nO܌�O� �j. ���`� ���=Y ���1 �J��A޸Ǒp*_�KH9ax� 1�+�Yb

Rթ`�U9<� �A#� endstream endobj 21 0 obj >>/BBox[0 0 612 792]/Length 80>>stream x�s ��w3T04P I�2P0T�5T R Ʀ zƆ !� n�E �E��y�9 �ũ �y9�z �!Y � ] ��5� � j endstream endobj 44 0 obj >>/BBox[0 0 612 792]/Length 131>>stream x� �; �0 ��ާ� 6^ǑL˫�B� plGJ�� !nO܌�O� �j. ���`� ���=Y ���1 �J��A޸Ǒp*_�KH9ax� 1�+�Yb

See also  beach wedding seeds

Rթ`�U9<� �A#� endstream endobj 47 0 obj >stream x�+� � | endstream endobj 48 0 obj >stream x�S �*�*T0T0 B ���� �ih��� �]� ” � �� c endstream endobj 49 0 obj >stream x�+� � | endstream endobj 50 0 obj >stream x�S �*�*T0T0 B ���� �id��� �]� ” � �’ ] endstream endobj 51 0 obj >stream x�+� � | endstream endobj 52 0 obj >stream x�S �*�*T0T0 B ���� �id��� �]� ” � �� Y endstream endobj 53 0 obj >stream x�+� � | endstream endobj 54 0 obj >stream x�S �*�*T0T0 B ���� �il��� �]� ” � �W _ endstream endobj 55 0 obj >stream x�+� � | endstream endobj 56 0 obj >stream x�S �*�*T0T0 B ���� �id��� �]� ” � �� e endstream endobj 57 0 obj >stream x�+� � | endstream endobj 58 0 obj >stream x�S �*�*T0T0 B ���� �ih��� �]� ” � �� W endstream endobj 59 0 obj >stream x�+� � | endstream endobj 60 0 obj >stream x�S �*�*T0T0 B ���� �ib��� �]� ” � �+ ] endstream endobj 61 0 obj >stream x�+� � | endstream endobj 62 0 obj >stream x�S �*�*T0T0 B ���� �ih��� �]� ” � � g endstream endobj 63 0 obj >stream x�+� � | endstream endobj 64 0 obj >stream x�S �*�*T0T0 B ���� �il��� �]� ” � �� c endstream endobj 65 0 obj >stream x�+� � | endstream endobj 66 0 obj >stream x�S �*�*T0T0 B ���� �id��� �]� ” � �� a endstream endobj 67 0 obj >stream x�+� � | endstream endobj 68 0 obj >stream x�S �*�*T0T0 B ���� �i��� �U� ” � �� � endstream endobj 69 0 obj >stream x�+� � | endstream endobj 70 0 obj >stream x�S �*�*T0T0 B ���� �i��� �U� ” � � � endstream endobj 71 0 obj >stream x�+� � | endstream endobj 72 0 obj >stream x�S �*�*T0T0 B ���� �ih��� �]� ” � �� [ endstream endobj 73 0 obj >stream x�+� � | endstream endobj 74 0 obj >stream x�S �*�*T0T0 B ���� �i��� �U� ” � �` � endstream endobj 75 0 obj >stream x�+� � | endstream endobj 76 0 obj >stream x�S �*�*T0T0 B ���� �ib��� �]� ” � �� a endstream endobj 77 0 obj >stream x�+� � | endstream endobj 78 0 obj >stream x�S �*�*T0T0 B ���� �i��� �U� ” � �n endstream endobj 79 0 obj >stream x�+� � | endstream endobj 80 0 obj >stream x�S �*�*T0T0 B ���� �id��� �]� ” � �; i endstream endobj 81 0 obj >stream x�+� � | endstream endobj 82 0 obj >stream x�S �*�*T0T0 B ���� �il��� �]� ” � � g endstream endobj 83 0 obj >stream x�+� � | endstream endobj 84 0 obj >stream x�S �*�*T0T0 B ���� �i��� �U� ” � � endstream endobj 85 0 obj >stream x�+� � | endstream endobj 86 0 obj >stream x�S �*�*T0T0 B ���� �il��� �]� ” � �k k endstream endobj 87 0 obj >stream x�+� � | endstream endobj 88 0 obj >stream x�S �*�*T0T0 B ���� �ih��� �]� ” � �S _ endstream endobj 89 0 obj >stream x�+� � | endstream endobj 90 0 obj >stream x�S �*�*T0T0 B ���� �il��� �]� ” � �� [ endstream endobj 92 0 obj >stream H��W�r�8 � � �) !x磓�[��xR � ��$l(� PR���’M %Rrf�������9��4 Y����3#k=�I� d��_�V�?g�H2� � I�”�yD�8�� ��3� , ̂�,p?��_gqD�(“� �� V���/f� ��b5�� 9�c�� �<�m�À����>�,fx Ҍ, ��y�G7 � ��?�=�>|�<&����?���� �����|��x�������Wl � Y � # ����nJ�0� ��� 5��&��<� W� j�7����q��.+����*I+�V(o���7��#