Hemp-nettle is a vigorous competitor for space and nutrients. Widespread in the Prairies, it is difficult to manage once it becomes established.
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An annual, reproducing by seeds, this weed has stems that are square and covered with bristly hairs. The stems are 30-75 cm (12-30 in.) high and are swollen at the nodes. The leaves are opposite, 5-10 cm (2-4 in.) long, coarsely toothed, hairy, and long-stalked. The flowers are clustered in the axils of the upper leaves and are white or pink, suffused with purple. The seeds can remain dormant for long periods of time, making it hard to manage this weed once it becomes established.
Each flower produces a cluster of 4 seeds. Hemp-nettle germinates best at high temperatures. It thrives in open, wooded areas, cultivated fields, and undeveloped areas.
Take a minimum of 20 weed counts across the field. Check low spots for patches. Scout fields early as the weed is most sensitive to herbicides in early stages.
Effects On Crop Quality
Hemp-nettle seeds are difficult to clean from grain.
Crops differ widely in their ability to tolerate this weed. Hemp-nettle densities of 150-225 plants per square metre (sq. yd.) can reduce wheat yields by 20-40%. Canola yields can be reduced by up to 25% at weed densities of 130 plants per square metre (sq. yd.). With densities of 400 plants per square metre (sq. yd.), hemp-nettle can reduce yields of oats by 30% and seedling alfalfa by 85%.
Sow clean, certified seed to prevent its accidental spread. Early sown, uniform stands of competitive crops such as wheat, barley and canola are effective at suppressing hemp nettle.
Herbicides are available in cereal crops, canola and peas. Flax and certain special crops are limited in terms of herbicide options.
What Is Burning Nettle: Getting Rid Of Burning Nettle Plants
You’ve likely heard of stinging nettle, but what about its cousin, burning nettle. What is burning nettle, and what does burning nettle look like? Read on to learn more about burning nettle plants.
Burning Nettle Plants
Burning nettle (Urtica urens) grows in various areas across the Eastern, Central and Western United States. It is a small to mid-size, upright, broadleaf weed with bristly, deeply serrated leaves. Small, greenish-white flowers appear from late spring until late autumn.
Burning nettle is found primarily in disturbed areas such as ditches, roadsides, fences rows and, unfortunately, in gardens. The plant earns its name, and if you accidentally brush up against the leaves, you’re unlikely to forget the experience.
Burning Nettle vs. Stinging Nettle
Burning nettle, also known as small nettle or annual nettle, generally reaches heights of 5 to 24 inches (12.5 to 61 cm). It is native to Europe. Stinging nettle (Urtica dioica), native to North America, is a much taller plant that can grow as tall as 3 to 10 feet (.9 to 3 m.), but can reach heights of 20 feet (6 m.) when conditions are just right.
Otherwise, the two plants share many similarities. Burning nettle germinates in a span of time from late autumn to early spring and blooms in winter and spring, although plants may produce greenish-yellow flowers all year in mild climates. Stinging nettle seeds germinate in spring and blooms appear from spring until autumn. Both nettle types display leaves covered with long, bristly hairs.
Getting Rid of Burning Nettle
Burning nettle plants are stubborn and getting rid of burning nettle requires persistence. Tilling sounds like a workable plan, but usually just distributes the rhizomes and makes the problem even worse.
Pulling the plants by hand is the best means of control, but be sure to protect your skin with sturdy gloves, long pants and long-sleeved shirts. Pull weeds carefully because any pieces of rhizomes left behind will generate more plants. You’ll have better luck at getting the entire weed when the soil is damp, and a garden fork or a long, narrow tool such as a dandelion weeder can make it easier to get the long taproots.
Always pull the weeds before they bloom and set seeds. You can also mow the weeds very closely, or cut them down with a weed trimmer – again, always before the plants bloom. Be persistent and pull new weeds as they sprout.
If all else fails, a glyphosate-based herbicide may be required but should always be considered a last resort. Keep in mind that the herbicide will kill any plant growth it touches.