Specialists Offer Control For Dandelions In Crops

PRINCETON, KY.

Dandelion has rarely been a major issue in grain crops, yet there is mounting evidence that it may be increasing as a problem in no-till corn and soybeans. Some of our northern neighboring states have experienced problems with dandelions in grain crops during the last few years and have observed that it is difficult to control with spring burndown applications.

   Dandelion is a simple perennial that is capable of reproducing from a branching taproot and from seed. The taproot of dandelion can compete effectively for soil moisture and contribute to the difficulty in controlling it with herbicides. The fact that plants produce numerous seeds (54 to 172 seeds/head and greater than 2,000 seeds/plant) that can be wind blown, also contribute to the problem with managing dandelion.

   Timing of foliar-applied herbicides influences burndown control of dandelion. Fall treatments (before a killing frost) is preferred over those applied in the spring. The effectiveness of spring burndown treatments may be improved if they are applied when dandelion plants are actively growing and prior to flowering.

   Specialists from Ohio State University and Purdue believe that preplant applications of Lumax plus 2,4-D ester tends to provide the best control of dandelion in no-till corn in the spring. The most effective burndown control in no-till soybeans is achieved with glyphosate plus 2,4-D ester plus a chlorimuron-containing product (i.e. Canopy, Canopy EX, or Valor XLT) or a cloransulam-containing herbicide (i.e. Authority First, Sonic or Gangster).

   When using 2,4-D ester in burndown treatments, wait at least 7 to 14 days after application before planting field corn. As a general rule, the preplant interval between application of 2,4-D ester and planting soybeans is 7 days for rates up to 0.5 lb ai/A ( 1 pt/A of 4 lb ai/gal product) and 30 days for rates >0.5 lb ai/A up to 1 lb ai/A (>1 pt/A to 2 pt/A of 4 lb ai/gal product). The labels of some 2,4-D ester products require only 14 or 15 - day interval when using rates >0.5 lb ai/A up to 1 lb ai/A. It is important to consult the product label to determine the appropriate herbicide rate and waiting interval and observe precautions to limit the risk of crop injury. Δ

Dr. Jim Martin is Extension Weed Scientist with the University of Kentucky at Princeton.