PPDL Picture of the Week
May 4, 2020
Dandelion (Taraxacum officinale)
Marcelo Zimmer, Weed Science
Program Specialist
Department of Botany and Plant
Pathology, Purdue University
Dandelion
is likely the plant species you think of when the term “weed” is mentioned. Almost everybody is familiar with its yellow
ray flowers and puffy white seed heads that you no doubt blew on when you were
a child. As adults you learn to dislike
those yellow flowers and white seed heads as you tirelessly pull and spray them
in your yard and flower gardens.
Dandelion is not only a weed of residential yards and pastures, but can
also become a problem in agricultural fields (Figure 1). This perennial weed is often overshadowed in
agronomic fields by pesky summer annuals like ragweeds, pigweeds,
lambsquarters, and foxtails; but it can become a major pest itself especially in
long-term no-till fields.
Dandelion
emerges in both the spring and fall and grows most vigorously in these two
seasons of cooler weather. Dandelion is also
a perennial weed that grows as a rosette and overwinters as a large taproot. Traditional agronomic practices such as
tillage limited the success of dandelion as tillage would bury the small seeds
below the soil surface and destroy the taproots. However, the increased adoption of no-till
practices has led to the increased prevalence of this perennial weed. Another shift in agronomic practices that may
have contributed to the increased prevalence of dandelion in row crops is early
corn planting. Corn residual herbicides
are applied earlier and crops are harvested earlier. The lack of residual activity and earlier
canopy opening allow for dandelions to flourish in the fall following crop
maturity and harvest.
Dandelion
control in no-till fields starts with a good burndown in the spring along with
a residual herbicide for both corn and soybean.
This burndown should include 2,4-D with either glyphosate or
gramaxone. Gramaxone applied alone will
provide an initial quick relief, but plants will rapidly regrow shortly after
application. The use of a residual herbicide
in both corn and soybeans will extend the control of dandelion throughout the
growing season. The following residual products
have exhibited the greatest control into the season when applied with a proper
burndown in Purdue University research trials:
No-till
Corn: Lexar EZ, Lumax EZ, and Bicep II Magnum
No-till
Soybean: Metribuzin, Authority XL, and Valor XLT