CHEMICAL WEED CONTROL IN STRAWBERRIES 



Dominic A. Marini 

 Regional Agricultural Specialist - Southeast Region 



Because of potentially high yields and strong demand, strawberries 

 can be a profitable crop. Control of weeds is essential to the attain- 

 ment of high yields, however, and since a strawberry bed occupies the 

 land for about 16 months , a great deal of hand labor may be required to 

 keep the bed weed-free. Because of the potential return, a greater in- 

 vestment in labor and other inputs can be justified with strawberries 

 than with many other crops. However, where labor is not available, or 

 where there is competition with other crops for labor, herbicides can 

 be used to substantially reduce the high labor requirement of strawber- 

 ries. 



Until recently, a satisfactory herbicide for use on strawberries 

 was not available. Now, 2 currently available materials, dacthal and 

 diphenamid, when used properly and under the right conditions, can pro- 

 vide satisfactory weed control. Both herbicides must be applied to a 

 weed-free soil, since they do not control established weeds. Further- 

 more, 1/2 to 1 inch of rain or irrigation is necessary following appli- 

 cation for good weed control, since they must be washed into the soil 

 to be effective. 



Dacthal is recommended at the rate of 8 to 12 pounds of the 75 per- 

 cent commercial product per acre. It remains effective for about 6 

 weeks, so several applications are required for season-long control. 

 A late summer or early fall application provides good control of chick- 

 weed, a serious problem in most strawberry beds. Dacthal may be applied 

 early in the spring, prior to weed germination to control weeds in bear- 

 ing beds. 



Dacthal is particularly effective against crabgrass and other annual 

 grasses, and against purslane, chickweed and lambs quarter. It is weak 

 against ragweed and red root pigweed, and poor against galinsoga, smart- 

 weed, mustard and other cruciferous weeds. Where galinsoga is a serious 

 problem, use of dacthal is not recommended. 



In some cases, injury has been observed where dacthal was applied, 

 appearing as a puckering of certain leaves and somewhat resembling virus 

 symptoms. It is not known whether or not this injury has any effect on 

 runner formation or on the crop. 



Diphenamid is recommended at the rate of 4 pounds active ingredient 

 per acre 5 pounds of the 80 percent product or 8 pounds of the 50 per- 

 cent product. It controls a wider range of weeds than dacthal and pro- 

 vides longer lasting control, but it may not be used within 12 months 

 of harvest. This means that only one application may be made, soon after 

 planting in April or May. Shallow cultivation improves its effectiveness. 

 No injury has been observed following its use. 



