2,4-D amine
Rate Spot treatment: 0.25 to 0.5% solution
Time Apply in spring to fully-grown leaves but prior to flowering.
Remarks 2,4-D is usually not able to fully control common fennel, so combining with other products is generally recommended. Retreatment will likely be necessary.
Caution Avoid drift to sensitive crops.
Site of action Group 4: synthetic auxin
Chemical family Phenoxy acetic acid
glyphosate
Rate 2.8 lb ae/A.
Time Apply in spring to fully-grown leaves but prior to flowering.
Remarks Adequate foliar coverage of fennel foliage is necessary. Add nonionic surfactant if not included in the formulation.
Caution Glyphosate is nonselective and injures or kills other vegetation in the treated area.
Site of action Group 9: inhibits EPSP synthase
Chemical family None generally accepted
triclopyr (Garlon 3A or 4)
Rate Broadcast treatment: 1 to 2 lb ae/A; spot treatment: 0.5 to 1% solution.
Time Apply in spring to fully-grown leaves but prior to flowering.
Caution Garlon 4 is an ester formulation; do not drift onto sensitive crops. Do not contaminate water.
Site of action Group 4 synthetic auxin
Chemical family Pyridine