Four further substances, including Atrazine and Diuron, have already been clearly proved to have an effect on hormones.

The compound may be used in combination with other herbicides such as atrazine, 2,4-D, bromacil, diuron, and sodium metaborate.

The triazine herbicides (including atrazine) and urea derivatives (diuron) are photosystem II inhibitors.

The pesticides concerned are: atrazine, simazine, isoproturon, chlortoluron, diuron, mecoprop, MCPA, carbetamide, fenpropimorph, clopyralid, dichlorprop and terbutryne.

Glyphosate, diuron and sulfonyl urea herbicides are most effective in eradication; herbicides should be applied at first sight of flowering because at this stage the bulbs will be exhausted.

Bromacil (40%) is combined with the active ingredient diuron in the herbicide Krovar, which is used by companies such as the Washington State Department of Transportation (WSDOT).