Trade name(s) Casoron, Barrier

Manufacturer(s) Chemtura, PBI/Gordon

Formulation(s) 50% wettable powder, 4% granules, 15.3% liquid

Remarks A nitrile compound used as a preemergent and early postemergent herbicide in noncrop areas and around established trees and shrubs. Dichlobenil is most effective when applied before weeds emerge, during cool weather, and immediately incorporated through irrigation or rain. It has little, if any, effect on foliage.

Water solubility 25 ppm

Storage conditions Store under cool, dry conditions to avoid volatility.

Acute toxicity LD50 - 5,000 mg/kg

Action in plant Inhibits meristematic tissue in growing points of roots and shoots.

Site of action Group 20: inhibits cell wall synthesis Site A

Chemical family Nitrile

Koc Average is 400 mL/g (estimated)

Site Preparation

Ed Peachey
Revised December 2013


glyphosate (numerous product names)

Rate Consult labels

Time Apply 1 to 4 weeks before planting to allow time for chemical to move completely into the roots of actively growing weeds.

Vegetation Control

Tim Prather
Revised June 2014

Total vegetation control with soil-residual herbicides is a process in which the addition of chemicals renders the soil unfit for plant growth. Soil-residual herbicides do not kill all animal and microbiological life in the soil.

Keep the following in mind when using soil-residual herbicides:

Established Tree, Shrub, Rose, and Ground Cover Landscapes

Ed Peachey
Revised March 2014

Multiply rate by 0.023 for amount per 1,000 sq ft


Available at agricultural and garden supply stores

Spun-bonded fabrics (non-woven) lightweight, extruded polypropylene fibers; requires mulch cover due to moderate UV light sensitivity; weed roots and rhizomes can penetrate fabric unless removed before establishment; cheapest option.

Weed Control in Field-grown Nursery Stock

Ed Peachey
Revised December 2013

Weeds compete with newly planted nursery stock. Deep-rooted perennial weeds can reduce vigor and render a mature product unmarketable due to laws on transporting noxious weeds. Consequently, weeds are controlled with herbicides either broadcast-applied in closely spaced crops, or within the tree or shrub row for wider spaced crops, with alleys being mowed or flailed.

Weed Control in Container-grown Nursery Stock

Ed Peachey
Revised December 2013

Sanitation The first step to effective weed management is sanitation. Start with potting mixes that are free from weed seeds. Control weeds that have wind-dispersed seeds around the perimeter of the site. If weeds emerge in containers, remove them before they produce seeds. The more weed seed allowed to contaminate containers, the higher the probability that the weeds will germinate in areas where the herbicide barrier has been weakened or disrupted.


Ed Peachey
Revised March 2015

RHUBARB—Winter Applications to Dormant Rhubarb

carfentrazone (Aim EC)

Rate Up to 0.031 lb ai/A (2 fl oz/A Aim EC)

Time After crop emergence, but only to row middles. Use hooded and shielded sprayers.


Kim Patten
Revised March 2015

Preplant weed control All major weed problems can be prevented by starting with a clean field and avoiding reinfestation.

Blueberries, Gooseberries, Currants, and Elderberries

Joe DeFrancesco and Ed Peachey
Revised March 2015


Mulches contribute significantly to weed control if constructed and maintained properly. Even without the benefit of weed control, blueberries grow well under mulch because they are shallow rooted and lacking root hairs. A layer of mulch over the soil conserves soil moisture for blueberries.

Blackberries and Raspberries

Joe DeFrancesco
Revised March 2015


glyphosate (numerous product names)

Rate Consult labels

Remarks Apply to weeds at least 10 days before planting crop. Use highest rate on field bindweed. Do not apply if weeds are stressed by drought, weather, or maturity. Rain within 6 hours after application may reduce effectiveness. Inhibits production of three amino acids and protein synthesis.

Vineyards and Grapes

Ed Peachey
Revised March 2015

(Note: Some clones may be sensitive to certain herbicides)

GRAPES—Weed and Vegetation Management

General strategy Vegetation management in vineyards is determined by site-specific environmental factors. Weed competition and interference must be minimized within the row while trafficability and soil conservation are required between rows (see “Section L. Vegetation Management in Orchards, Vineyards, and Berries” in this handbook).

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