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Weed Control

Satisfactory weed control is essential to ensure that:

  • the crop is able to achieve its full yield potential
  • the combining and drying operation is not slowed down by the presence of green material at harvesting
  • quality is maintained by producing a seed sample that does not have an admixture of weed seeds in it.

Beans are very susceptible to weed competition in their early stages of growth and therefore a good weed control programme is essential.

Perennial weeds and scutch grass should be controlled in the previous crop or stubble with an application of glyphosate.

For pre-emergence annual broad leaved weed control, choose from the following herbicides:

  • Nirvana (pendimethalin + imazamox)
  • Lingo (clomazone + linuron) + 800 g ai/ha pendimethalin

Pre-emergence herbicides are the most suitable and should be applied as soon as possible after sowing and where carried out, rolling. Avoid spray overlaps as bleaching can occur. There should be 13 mm clay cover over the emerging bean to avoid crop damage.

Grass weeds can be controlled effectively with an appropriate graminicide.

Grass-Weed Control

  • Stratos Ultra 1.5-4 l/ha (from 3 node stage of the crop until before the crop canopy prevents adequate spray penetration).

A satisfactory crystal violet test must be performed before spraying Aramo or Stratus Ultra.

Weeds

Weed control in beans has proven difficult in recent years.

  • Use glyphosate before sowing for perennial weeds and to lower the overall weed burden.
  • Residual products work best on fine seedbeds with some moisture after spraying.

Nirvana (pendimethalin + imazamox). Nirvana (BASF) must be applied before the beans are within 13 mm from the soil surface. The recommended rate is 3.0 - 4.5 l/ha. The higher rate high rainfall areas for maximum persistence and high weed situations.

Lingo is a mixture of clomazone + linuron. It is a pre-emergence option and should not be applied to broadcast crops. It will normally be applied at 2.0 l/ha + 800 g ai/ha pendimethalin. Avoid spray overlaps as transient crop effects (bleaching) can occur.

Basagran is the only post-emergence BLW product available for beans. Use up to 3 l/ha from the 2 leaf stage of the bean. Weeds are best controlled using Basagran when at the cotyledon stage. It can be hard on the bean crop (especially in cold weather) so do not tank mix with any other pesticide.

Off-label recommendations cleared for use on beans by the Pesticide Control Service include: pendimethalin products (below) applied up to 1320 g ai/ha and Defy applied up to 5 l/ha.

 NirvanaDefyLingoPendimethalin
Black bindweed S (MR) S  
Charlock S (MS) S  
Chickweed S SS S S
Cleavers (MR) S S  
Dead Nettle, Red S S S S
Fat Hen S (MR) S S
Fumitory S (MS)   MS
Groundsel (MR) (MS) S  
Knotgrass S (MR) S S
Mayweed MS      
Meadow grass (S)     S
Nightshade, black (MS) S S MS
Oilseed rape (MS)     S
Parsley, fools MR   S  
Pansy, field MR MS   S
Poppy S     S
Redshank S (MR) S  
Shepard's Purse MR (S) S  
Sowthistle, smooth (S)   S  
Speedwell, common S S S MS
Speedwell, ivy leaved S S   MS
S=Susceptible; R=Resistant; M=Moderate; ( ) = no label claim

Grass weeds can be controlled effectively with an appropriate graminicide.

Graminsides for Wild Oats and Scutch Control

  • Fusilade Max @ 1 - 3 l/ha (from second node stage but before first flower bud visible)
  • Stratos Ultra 1.5 - 4 l/ha (from 2 leaves of the crop until the canopy prevents adequate spray penetration)
  • Falcon 0.7 – 1.5 l/ha (from 2 leaves of the crop until before flower bud is visible)

Products that are cleared for use on peas and beans are available at:
www.pcs.agriculture.gov.ie