Berry Crops: Introduction


Pub 75: Guide to Weed Control > Berry Crops > Berry Crops: Introduction


Excerpt from 2010-2011 Chapter 14, Publication 75, Guide to Weed Control, Order this publication

Cover of Publication 75, Guide to Weed ControlTable of Contents

  1. Cultural Weed Control in Berry Crops
  2. Perennial Weed Control
  3. Site Preparation
  4. Mulching
  5. Reducing Weed Pressure
  6. Rotating Herbicide Families
  7. Herbicide Application Timings
  8. Related Links

In April of 2009, the Ministry of Environment ammended the Pesticides Act with the Cosmetic Pesticides Ban Act, 2008 and Ontario Regulation 63/09. Pesticides are now classified for sale and use under 11 different classes. It should be noted that agriculture (e.g. nursery production) is exempted. For more information on the legislation see the Ministry of the Environment’s website at www.ontario.ca/pesticideban.

 

Cultural Weed Control in Berry Crops

A successful weed control program must integrate cultural and chemical weed control practices. Growers cannot depend entirely on chemical weed control in berry crops, since there is a limited spectrum of herbicides registered for these crops.

 


Perennial Weed Control

It is important to identify and control perennial weeds in the preplanting year. It is very difficult to control perennial weeds once a planting is established because of crop sensitivity to some herbicides and since it is not possible to clean cultivate in established berry crops.


The following perennial weeds present serious problems in these crops: quackgrass, bindweed, vetch, wild grape, perennial nightshade, thistles, ground-ivy (creeping charlie) and burdock. In strawberries, sheep sorrel, toad flax and milkweed also present problems.

Systemic herbicides such as glyphosate (e.g. ROUNDUP) or amitrole (e.g. AMITROL 240) should be applied to perennial weeds in the preplanting year. Consult the product label and be sure to use the recommended rate for the weed in question. Apply the herbicide at the proper stage of growth of the weed, otherwise only temporary control will be achieved. Repeated cultivation of some perennial weeds such as bindweed will also provide control.


Site Preparation

A green manure crop such as perennial ryegrass or Sudan grass should be established in the preplanting year following or in conjunction with measures to control perennial weeds. This crop will provide competition to reduce weed growth as well as improve the soil structure. Non-selective herbicides can be applied before planting the green manure crop and before plowing it under. Short residual selective herbicides such as 2,4-D may be used with the green manure crop, but avoid using herbicides that leave a soil residue that will carry over into the planting year. See Chapter 6, Preplant-Site Preparation Prior To Any Crop, page 81.


Mulching

For bramble and bush fruit, biodegradable plastic mulch could be used for weed control in the planting strip. Straw mulch will also assist in weed control beneath the plants or in the planting strip if it is applied early in the season before the weed seeds germinate.
Use mulch that is free of weed seeds and ensure that enough nitrogen is provided for the plants. The mulch should be pulled away from around the plants for winter rodent protection.

For strawberries, use of straw mulch before weeds germinate can help control weeds. Some growers are trying plasticulture as a way to improve weed control.

 


Reducing Weed Pressure

Cultivation can provide weed control between the rows. In bramble and bush fruit, a vigorous sod between the rows will prevent weeds from becoming established. It is better to seed in a fescue sod rather than rely on a natural sod composed of weed and grass species, because the weeds will seed into the herbicide strip.

Prevent weeds from setting seed in adjacent uncropped areas by using cultural or chemical weed control measures. Mowing at regular intervals will prevent many weeds from flowering. Try to control weeds that escape before they set seed, by cultural removal or chemical mowing. In some situations, tools such as a weed whip may be of use. Mowers are available which will cut close to the plants without injury. Mowing, however, will not eliminate weed competition.

 


Rotating Herbicide Families

(See Table 4-6, Herbicide Groupings in Ontario, page 65)

In perennial crops, rotation of herbicide families is important to minimize the building up of seed from weed escapes, including triazine tolerant weeds. Rotation will also help avoid an accumulation of herbicide residues in the soil that may result in crop injury over a period of years and may hinder replanting.

 


Herbicide Application Timings


Preplant (PP) Treatments
Preplant treatments are applied before the berry field is planted. Some of these herbicides kill seedlings soon after germination while others also kill weed seeds. Most herbicides used for these treatments must bethoroughly incorporated into the soil by cultivation soon after application. Check the label. Also see Preplant Weed Control, Preplant Site Preparation Prior To Any Crop on page 81 for details of products, rates and remarks.


Preplant (PP) Weed and Cover Crop Control
Control cover crops and emerged weeds before planting berry crops. Refer to Table 6-1. Non-Selective Herbicides Available for Preplant Site Preparation, page 77. Alternatively, a grower may choose to kill the cover crop and/or emerged weeds just before planting the berry crop and either till the area or leave the seedbed untilled.


Preplant Incorporated (PPI)
Two incorporations at right angles operating at a depth of 10 cm using a double disk (7–10 km/hr) or vibrating shank S-tine cultivator (10–13 km/hr) are required unless otherwise stated. Cultivation-type equipment used for herbicide incorporation is known to spread perennial weeds to previously uninfested areas. Special attention should be directed toward machinery cleanliness, and/or treating fields with perennial weeds last.


Preemergence (PRE)
Rainfall at 15–20 mm within 7–10 days after application is necessary to activate preemergence treatments. Shallow cultivation, rotary hoeing or harrowing will control weed escapes and improve herbicide activity in the absence of rainfall. These materials prevent emergence of many weed seedlings without reducing crop stand. Apply immediately after seeding or at least before the emergence of the crop. If these materials are applied after weeds have emerged, kill is usually poor. Best results are obtained with this method when conditions for weed seed germination are good.


Postemergence (POST)
These chemicals are applied after the berry crop is planted. Applied as directed, the weeds can be killed without injury to the crop. Leaf stage of the weeds is critical for good control. Smaller weeds are generally easier to kill but there needs to be enough leaf surface to intercept the herbicide. Apply according to recommended leaf stages. Crop stage is important to optimize crop safety. Adjuvants will frequently improve the weed control when used as directed. Weather or other conditions may influence the optimum rate of adjuvant, see the product label for more details. Always use appropriate drift management technology.


Inter-row Weeding
The herbicide is directed between the berry crop rows onto the emerged weeds. The herbicide is used as a rescue operation where other methods of weed control have failed. Use special low pressure (7–15 kPa) applicators such as dribble bars or vibra jets equipped with shields to prevent wetting the crop. See Stale Seedbed and Inter-Row Weeding, page 82.


Wiper Applicators for Selective Weed Control
Wiper applicators (rope-wick, roller applicator or similar device) have been extensively used with glyphosate (ROUNDUP). Check product labels for use of this application technique with other herbicides.

 

Related Links

 

 


For more information:
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E-mail: ag.info.omafra@ontario.ca
Author: OMAFRA Staff
Creation Date: 25 November 2002
Last Reviewed: 08 June 2010