County Extension Office IDs new weed

During the recent crop tour, the presence of a new weed in our area was discussed. It is Narrowleaf hawksbeard, a relative of the dandelion. This weed is very prolific and will take serious management considerations in crop and summer follow for clean fields. Here is some information on biology and management . Any reference of chemical name is no endorsement of the product.

Identification

Narrowleaf hawksbears is a winter annual and sometimes summer annual – but a real opportunist. Narrowleaf hawksbeard is a tap rooted annual of the Asteraceae family native to Eurasia. Plants have yellow flowers, a basal rosette similar to dandelion, and may reach up to three feet tall (hence its nick-name “dandelion on steroids”). Leaves are 0.75-4 inches long, egg shaped (with the wider portion

towards to the tip) to linear-lance shaped, and margins are dentate to shallowly lobed. Basal rosette leaves have a stalk, and soon wither upon flowering. Upper leaves are more linear and lack a stalk.

Plants emit a milky sap when leaves are torn. In contrast to dandelion, there are leaves on the

flowering stem, and plants can become highly branched. In the rosette stage, they are much trickier to differentiate.

Control

Rosettes in the fall are most vulnerable. Best control is 2,4-D amine at a pint to the acre. Each plant can produce up to 50,000 seeds. The plants are set back by glyphosate, but the seed heads come back with a vengeance in multiplied numbers. Mowing is an option, but it requires three mowings to stop the seed production. Plants in the flowering stage may still go to seed if cut. Once the plant bolts it is very difficult to control especially within crop rotations. Sulphonyl ureas work, but they limit the options for plant back. There is no effective control in pulse crops or oil seed crops.

Pre Plant/Fall Burn Down

Sharpen + glyphosate

Panoflex + glyphosate

Quelex (Arylex + florasulam) + glyphosate

Quelex is a Dow Agrisciences product that is a group 4 active ingredient (auxinic like 2,4-D) it may be active on ALS resistant weeds. They are doing research in the field at this time. Apparently it is rapidly degraded by microbial activity such that you can plant back to peas, but it may have some residual in high pH soils such as 8.0 to 8.5.

In crop, Wheat

Huskie

Starane Flex

Goldsky

Affinity Broadspec, Express as tankmix partners

If you have specific questions about this weed, contact the Phillips County Extension Office, 654-2543.