Vegetable herbicide formulations

By Barry Tickes, UA Area Agriculture Agent

While there have been few new herbicides developed for vegetables over the past 20 years, new formulations of old products have slowly become available. Some of the new formulations have been developed after active ingredients came off patent as a means of differentiating and improving new products.

Five of the most notable vegetable herbicides with new formulations are Kerb, Dacthal, Prowl, Goal, and Select. For the first time since Kerb 50W was registered in 1964, the product will be available as a liquid suspension concentrate. This formulation contains 3.3 pounds of Pronamide per gallon. 1.25 pints to 2.5 pints is equivalent to 1.0 to 2.0 pounds of the old 50W. Otherwise the label is the same.

Dacthal (DCPA) was first registered as a 75WP (wettable powder) in 1958. A flowable formulation was first sold about 10 years ago. The flowable contains 6 pounds of the active ingredient per gallon and 1.0 pint of the 6F is equivalent to 1.0 pound of the old 75WP which is still available.

Prowl was first registered in 1975 as an emulsifiable concentrate. A water-based encapsulated formulation (H2O) was developed and registered about seven years ago.

The active ingredient, Pendimethalin, of the H2O formulation is encapsulated in a polymer coating that swells and ruptures when diluted with water. It requires much more agitation to stay in suspension than the EC formulation. The original formulation contains 3.3 lbs. of active ingredient per gallon while the H2O formulation is a little more concentrated and contains 3.8 pounds per gallon.

Goal was first registered in 1979 as an emulsifiable concentrate. A water-based flowable formulation, GoalTender, was registered about five years ago.

This newer formulation has increased crop safety and less potential “lift-off” from codistillation with water. The older 2XL formulation contained two pounds per gallon of the active ingredient pronamide while the newer formulation contains four pounds per gallon and requires half the rate of the 2XL.

Select was first registered in 1991 as an emulsifiable concentrate. It was registered at the same time in California as Prism. Select contained two pounds per gallon of the active ingredient clethodim and required half of the rate of Prism which contained one pound per gallon. Several other formulations became available when this product came off of patent that contained one to two pounds active ingredient per gallon.

Select Max was registered about five years ago. This product contains one pound per gallon of active ingredient and does not require the addition of a crop oil concentrate adjuvant required with the other formulation.

Contact Tickes: (928) 580-9902 or btickes@ag.arizona.edu.

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