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Monsanto Advisory Note

Date Added: 08/08/2012

MONSANTO NOTES ON THE EFFECTS OF USING OILSEED RAPE SEED AFTER TREATMENT PRE-HARVEST WITH ROUNDUP®

All Monsanto glyphosate labels clearly state that pre-harvest glyphosate should not be applied to seed crops.

Using glyphosate treated Farm Saved Seed is at the farmer's own risk and Monsanto would strongly advise against this use because the effects on the following crop are difficult to predict. Certified seed crops would be rejected if desiccated with Roundup®, but each year some Farm Saved Seed is retained by growers, often in error.

Even where germination tests are used to adjust seed rates there is still an increased risk to seed quality and a reduction in crop vigour is possible depending on the amount of glyphosate in individual seeds.

What are the effects?

Glyphosate affects germination by producing abnormal seedlings with shorter, stumpier roots and fewer root hairs. However a good germination test result is not necessarily an indication that the seed quality is unaffected.

The mode of action of glyphosate is to interfere with protein synthesis, thus affecting new growth and leading to stunting of the plants. The affected seedlings may eventually grow away as the glyphosate is diluted in new growth, but an uneven crop often results. Yield effects range from almost nil where the proportion of affected seeds is low to severely reduced yields. This can lead to further difficulties in crop management - e.g. increased risk of slug or pigeon attacks, weed infestation etc.

Why does this happen?

If a crop is sprayed with glyphosate when the seed is physiologically immature there can be translocation into the seed. The recommended timing is 30% or less moisture in the seed; at which point the seed is ripe and translocation into the seed does not occur. However, oilseed rape has an indeterminate flowering habit and a proportion of the seed in the top pods will always immature and prone to the uptake of glyphosate.

Seed which has taken up glyphosate will produce a shoot from seed reserves and pass a germination test but still be affected once it reaches cotyledon stage, starts to photosynthesise and mobilises the glyphosate.

What to do if you still want to use Farm Saved Seed?

If farmers still intend to save seed from a crop that may have been sprayed, they should always:

  • Check germination using an Official Seed Testing Organisation
  • Request a full germination test and never a rapid ‘Tetrazolium test'
  • Inform the organisation that it has been sprayed with Roundup®.

o The lab will look specifically for abnormal growth effects

Monsanto Technical Helpline (01954) 717575

e-mail technical.helpline.uk @monsanto.com website at www.monsanto-ag.co.uk

Roundup® products contain glyphosate.

Roundup is a registered trademark of Monsanto Technology LLC.

USE PESTICIDES SAFELY. ALWAYS READ THE LABEL AND PRODUCT INFORMATION BEFORE USE
©Monsanto UK Ltd 2012(MS)

 

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