First, make sure to understand the nomenclature when reading herbicide labels.  Bushberries include blueberries, currants, gooseberries - all those multi-stem shrubs.  Caneberries are brambles.  Elderberries are usually in the category of bushberry, as are Juneberries. 

Bushberries and Caneberries

One of the earliest herbicides that can be used is Casoron.  Casuron has two different formulations: Casuron 4G (granular) can be used in bushberries, caneberries, and cranberries. The granular material should be applied before May 1st but the earlier the better.  If you are applying it in April, make sure to apply before soil temperatures exceed 45 degree F and before any annual weed seeds germinate. Casoron CS (not labeled for Ribes) can be applied a bit later but still needs to be incorporated by rainfall before weed germination; it is labeled for 1 year old blueberries, as well as blackberry and raspberries if applied before new shoot emergence. Casoron controls annual grasses and broadleaves, as well as some perennial grasses.  Follow Casuron with a post-emergent such as paraquat to kill pre emerged weeds or apply glyphosate when weeds are actively growing.

Another pre-emergent is Surflan.  Again there are two formulations.  Surflan AS can be used in non-bearing and bearing brambles at a rate of 20-40 gallons per acre. To broaden the spectrum of weed control, tank mix Gramaxone, Princep or Solicam. Irrigate product in to activate material. Surflan XL 2G can only be applied to non-bearing brambles.

Princep, Devrinol, Axxe, Solicam or Sinbar can all be applied for pre-emergent weed control in brambles and blueberries. These herbicides generally do not do a great job on all weeds and need to be evaluated as to your weed population and which tool makes the most sense.

Sandea and Velpar are two products that are only labeled for blueberries.  They can both be applied in early spring although Sandea's real strength is that it controls nutsedge.  This can only be accomplished as a post-emergent directed spray.

Velpar can be applied to bushes that are 3 years or older. It should be applied before the foliage on the lower limbs break bud. Effects of Velpar L vary from one soil type to another.  I've seen growers use Velpar to control annual weeds, but it also seems to have some effect on perennial weeds as well.

Strawberries

Late winter or early spring after winter annual broadleaf weeds have broken dormancy, but before strawberries begin to grow, is a key time for herbicide application. Apply 2,4-D amine, Formula 40 or other labeled 2,4-D formulations, in late winter or early spring to control emerged winter annual broadleaf weeds.

Add Chateau to provide residual annual broadleaf weed control. Use 1 quart of Formula 40 per acre and 3 dry ounces of Chateau after the soil is no longer frozen but before strawberries break dormancy and begin to grow. Chateau can be used once in each calendar year. If Chateau was used in the late fall of last year, Chateau can be reapplied in the March or early April but not used again in the calendar year. The crop will "out-grow" small application injury that may occur, but do NOT apply after the crop has broken dormancy and begun to grow or lasting injury may result.

Note the pre-harvest interval (PHI) for Sinbar use in strawberries is 110 days. This effectively eliminates late winter and early spring applications of Sinbar to strawberries before harvest. A typical strawberry field grown using the matted row system begins to bloom about May 1st and harvest begins in late May or early June. The cut-off date for the 110 day PHI would be sometime in February and has already passed.