Herbicides can be used safely and effectively to control weeds in bramble plantings. In addition to reducing weed problems, herbicides minimize the need for mechanical weed control and the physical injury to the crop that often results. Herbicides should be considered for most commercial plantings.
Herbicides are used primarily to reduce the weed problem in the row area itself. Weed growth between the rows can be minimized with early establishment of sod and regular mowing. Cultivation between the rows is also an option; however, this practice can deplete soil organic matter and lead to severe soil erosion.
Controlling Perennial Weeds
Controlling perennial weeds before planting brambles is important to minimize competition between the crop and the weeds during the establishment year and later years of production. Uncontrolled weed growth in the planting also exacerbates disease problems in brambles by minimizing air movement through the plantation, thereby maintaining higher moisture levels on foliage and stems of the crop. Wild brambles, such as wild blackberry (Rubus, spp.), serve as a source of disease inoculum to the crop and must be completely eliminated from the field and immediate surroundings prior to planting.
Quack grass (Elytrigia repens), Canada thistle (Cirsium arvense), wild brambles, and field bindweed (Convolvuls arvensis) spread and reproduce mainly by underground root stocks or rhizomes. A plowed and disked field may appear to be free of these weeds; however, unless steps were taken prior to tillage to control the underground portions, reinfestation is often rapid. Perennials are difficult and costly to control once a crop has been planted. When used in combination with tillage, Roundup or Touchdown applied directly to perennial weed foliage before plowing and planting is the most effective means to control perennials. Herbicide application must be timed correctly and the correct rate used. The treatments given here will provide the best control of perennials and will control emerged annual weeds as well.
Quack Grass
Quack grass and many broadleaf perennial weeds are best controlled with fall herbicide applications. Do not plow after harvest. Quack grass (and most other grasses that might occur in the field) should be about eight inches tall when treated. Fall frosts before spraying generally will not affect control provided at least 60% of the foliage is still green when you spray. However, an extended period of drought just before spraying may adversely affect control.
For long-term control of quack grass in sod ground use Roundup Ultra at 1 to 2 quarts per acre or Touchdown at 3.33 pints per acre. Use the one-quart-per-acre rate of Roundup Ultra in 5 to 10 gallons of water per acre on land that has been in row crops. The two-quart-per-acre rate will provide longer lasting control when spraying sod. After spraying, wait at least three full days (72 hours) before plowing but generally don't delay plowing more than seven days. Quack grass may recover somewhat from the treatment if tillage is delayed until the weed foliage has turned brown. If spring applications of glyphosate become necessary, don't fall plow; simply wait until quack grass reaches the right growth stage (four to five new leaves in this scenario) and spray. Spring applications will generally not provide good control of broadleaf perennials.
Dandelions (Taraxacum officinale) and some other broadleaf weeds are killed more rapidly with tank-mixes of either Roundup Ultra or Touchdown with 2,4-D amine (add 2,4-D at a rate of one pint per acre). However, the risk of damaging sensitive vegetable or fruit crops with 2,4-D drift or spray-tank residue is high! Take steps to eliminate spray drift.
Canada Thistle
Canada thistle can be treated in the flower bud to flowering stage in late spring or during the rosette to flower bud stage during late summer or fall. In summer fallow systems, tillage should stop in late July, and thistles be allowed to regrow for at least five weeks. Apply Roundup Ultra or Touchdown before a killing frost and when Canada thistle regrowth reaches the flower bud stage or is at least 10 to 12 inches high. Apply Roundup Ultra at two to three quarts per acre in five to 10 gallons of water or Touchdown at two quarts per acre. Spot sprays of a 2% solution (0.5 pints in six gallons of water) of either herbicide will also be effective.
Field Bindweed
Field bindweed must be treated when it is actively growing and at or beyond bloom. Fall treatment is best but apply herbicides before a killing frost. Apply Roundup Ultra at three to four quarts per acre or Touchdown at 5.33 pints per acre. Alternatively, spot spray with a 2% solution of either product (0.5 pints in six gallons of water).
Wild brambles, such as wild blackberries, are persistent and more than one season of control measures may be required to completely eradicate them. Use a foliage and stem treatment of 2,4-D and 2,4-DP (various factory formulated mixes available) at a rate of two to four quarts per acre of product in 100 gallons of water. Apply at any point from the time leaves are completely mature until plants start to go dormant, being sure to completely cover all foliage and canes.
Immediately After Planting
Apply Devrinol 50-DF at eight pounds per acre soon after planting once the soil has settled around the plants and before seedling weeds emerge. Devrinol controls most grasses from seed and some broadleaf weeds from seed. It may require irrigation or shallow mechanical cultivation to activate the herbicide if rainfall does not occur. Devrinol 50-DF can also be applied in the fall to freshly tilled ground to control winter annual weeds. In fruiting years, do not apply this product after first bloom.
Or:
Apply Simazine at 0.5 pound active ingredient (a.i.) per acre (various formulations
and concentrations available) after planting once the soil has settled around
the plants. Simazine is most effective if applied before weed emergence and
controls annual broadleaf weeds emerging from seed. Generally with Simazine,
avoid pH above 6, very light sandy soil, and soils with less than 2% soil organic
matter (SOM). In subsequent years, use 1.0 pound a.i. per acre. Various formulations
are available, and product rates for use in the planting year are provided here.
Drexel Simazine 4L, Princep 4L, and Riverside Simazine 4L: apply one pint per
acre.
Drexel Simazine 90-DF, Caliber 90, and Riverside Simazine 90-DF: apply 0.55 pounds per acre.
Or:
Apply Surflan A.S. at two to six quarts per acre after planting and before
seedling weeds emerge. Length of control varies with the rate used. Surflan
controls a number of annual grasses and broadleaf weeds emerging from seed.
One-half to one inch of rain or irrigation water is required within 21 days
to activate the herbicide. Surflan can be used in subsequent years as well.
Research in Ohio shows pre-emergent dandelion control by mixing 1.3 pounds per
treated acre of Gallery 75-DF with Surflan. Gallery also controls several other
broadleaf weeds.
Controlling Emerged Grasses
Apply Fusilade DX at one to 1.5 pints per acre to emerged annual grasses two- to eight-inches tall. A nonionic surfactant or crop oil must be added to the spray tank. Perennial grasses are sensitive, but time of application is species specific (information provided on the label). This product is registered for the planting year only.
Or:
Apply Prism to actively growing annual or perennial grasses. Use 13 to 17 fluid ounces per acre for annual grasses and 17 to 34 fluid ounces for perennial grasses. Use the higher rates when weed pressure is intense or weeds are large. Always use a crop oil concentrate at 1% U/U but not less than one pint per acre. This product is for planting year only.
Or:
Apply Poast at 1.5 to 2.5 pints per acre to actively growing annual and perennial grasses. Always add crop oil concentrate at two pints per acre. Use the higher rate to suppress perennial grasses. The pre-harvest interval for raspberries is 45 days. This product can only be used on blackberries during the planting year.
Controlling Emerged Weeds
Apply Dichlobenil at 4 pounds of a.i. per acre to established plantings in
the late fall or winter but before any growth commences in the spring. Apply
the herbicide in a band under the row to give the desired weed-free zone. Be
careful to adjust the rate used to account for the band width. Dichlobenil controls
many emerged annual and perennial grasses and broadleaf weeds. Two products
are available:
Casoron 4G applied at 100 pounds per treated acre.
Dyclomec 4G applied at 100 pounds per treated acre.
Spot sprays or wiper applications of Touchdown or Roundup Ultra can be used to control small patches of perennials in most crops after emergence or transplanting. The risk of localized crop injury is very high: thus, these treatments should be applied by skilled operators.
The herbicides recommended for use in bramble plantings are most effective as a means of preventing rather than overcoming weed problems. Most are best applied at low pressures, 30 to 40 pounds per square inch in 20 to 25 gallons of water per acre of sprayed area. Most herbicides persist in the soil and are applied before growth starts in mid-March to avoid contact with growing bramble plants. Be sure to provide agitation to the mixture in the spray tank to ensure even distribution of the herbicide.
Hand and tractor-mounted granular-application equipment is available. Granular applications may prove more useful in small plantings than the more conventional sprayer technique.
Growers are urged to consult and follow the latest Ohio State University Extension recommendations before making any herbicide applications to bramble plantings. Refer to Bulletin 506-B in Ohio, which is available from your county OSU Extension office.