Planteværn Online > Skadevoldere - Weed biology<br> <sub>Agro-region: Denmark</sub> - Scentless Mayweed ALS-res

Crop Protection Online

25.4 2024

Weed biology
_{Agro-region: Denmark}

Scentless Mayweed ALS-res

Can be mistaken for

Corn Chamomile, which has sparse hairs on true leaves.

Corn Marigold, which is blue/green and with a substantial layer of wax (greyish surface).

Mugwort, which has hairy true leaves.

Pineapple-weedwith maximum 2 incisions on the first 2 true leaves.

Scentless Mayweed that is morphologically identical but not resistant to ALS-herbicides

Scentless Mayweed SU-resthat is morphologically identical but only resistant to SU-herbicides

Resistance to herbicides

There have been significant populations of this weed in Denmark, which requires special considerations in the control. Read more here.

Characteristics

Cotyledons
Oval with entire leaf margins. Unstalked. Smooth surface. Length approx. 4-6 mm.

True leaves
The first true leaves have many deep incisions. Stalked. Smooth surface. Length approx. 10-12 mm. Later true leaves are pinnatisect.

Mature plant
Scentless Mayweed is a high plant (30-70 cm), which can become very vigorous, especially in open crops. The diameter of the flower is approx. 40 mm. Seed production: Up to approx. 34,000 seeds per plant.

Seed
Shaped like a slightly curved, truncated 3-4-sided cone. The surface has 3-4 longitudinal, light veins. Two types can be found: broad ray seeds and more slender disc seeds. Thousand grain weight approx. 0.35 g.

Biology

Propagation and dispersal
Only through seeds.

Habit
Summer and winter annual.

Importance

The species is found very frequently in both autumn- and spring-sown crops throughout Denmark. The species is an injurious weed, which causes losses in all crops. In a large number of seed crops Scentless Mayweed is a troublesome weed because it is difficult to separate the seeds.

For treatment options, consult 'Herbicides Across'.
For more options, consult 'Main Menu'.

Taxonomy

Compositae.

Names in different languages

Danish :	Kamille, lugtløs ALS-res
German :	Duftlose Kamille ALS-res
English :	Scentless Mayweed ALS-res
Latin :	Tripleurospermum inodorum ALS-res
Norwegian :	Balderbrå ALS-res
Swedish :	Baldersbrå ALS-res

Seedling

Early stage

Flower head

Mature plant

Seeds

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Weed biology Agro-region: Denmark