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Pulse Topping In Legumes and The Use of Sharpen Herbicide

With harvest fast approaching and legume yields looking favourable there is no better time to start looking at pulse desiccation options.  Spray topping Legumes is an important part of controlling resistant grass weeds and is an extremely important tool for reducing problem or resistant weed seed set as well as reducing green trash for ease of harvest. Fortunately, this year both Glyphosate and Paraquat are at an attractive price, giving even more reason not to compromise on desiccating pulse crops to ensure good weed seed management.      


Sharpen herbicide (700g/kg SAFLUFENACIL) is registered for application prior to harvest on field peas, faba/broad beans, chickpeas, lentils, and lupins and can be added to Paraquat or Glyphosate for improved results.  This can be an effective tool to help manage herbicide resistance, particularly on problem weeds such as Wild Radish and other hard to kill weeds like sow thistle and prickly lettuce. Sharpen has recently come back in price which also makes it an attractive option this spray desiccation period.


Sharpen is also registered in wheat and barley for late wild radish seed-set control. Given the wet conditions in the Western Districts of Victoria and difficulty faced by many growers getting onto paddocks this may prove a viable option for growers looking to reduce radish seed set for the following years crop. Sharpen is registered for late application (GS71-GS83) without the addition of Paraquat or Glyphosate it can reduce the wild radish seed set remarkably, example of this is shown below.


Photo 1. Untreated control (Left) vs Sharpen applied at 34g/ha + 1% v/v MSO for control of wild radish seed set in wheat


The 5 Key points to consider when using Sharpen:

  1. Always use with 1% Hasten

  2. Use minimum 100L/ha water.

  3. DO NOT use for Lentil seed crops

  4. DO NOT add an acidifying agent such as LI 700

  5. Apply when pulse seeds have reached full physiological maturity and at least 7 days before harvest


Benefits of Sharpen to your pulse harvest:

  • Rapid desiccation and dry down of winter pulse crops

  • Manage uneven crop maturity which can delay harvest

  • Quick dry down of leaves, stems and green pods

  • Reducing green trash resulting in improved harvest speed and efficiency

  • Desiccates and reduces the biomass of late germinating broadleaf weeds

  • An alternative mode of action to existing desiccants Paraquat and Glyphosate

  • Valuable tool for resistant management of hard to kill broadleaf weeds


Application timing:

  • Faba beans :  Hilum black in top pods at the top of the canopy (30 – 80% pods ripe and dark)

  • Chick peas:  80 – 85% of pods within crop have turned yellow-brown.

  • Lentils:  Just after crop starts to yellow (Or senesce).  When 40 – 70% yellowing of plant material. This is visually late in the crops life as the image below highlights.  It's similar timing to a Diquat application rather than the earlier timings traditionally used with Gramoxone. *Please Note: Sharpen may have a negative effect on lentil germination. DO NOT use Sharpen on crops for seed production.

  • Narrow leaf Lupin -: At 80% Leaf drop, leaves turned brown.  Seed should be changing colour from light green to yellow. 

  • *Please Note:  Apply Sharpen to direct harvested Lupins ONLY.  Application prior to windrowing can result in severe loss of grain yield.

  • Field Pea -:  Apply when field peas reach 30% moisture content, or when the lower 75% of pods are brown and leathery with firm seeds.

  • As always it’s best to consult your Western Ag agronomist for more information regarding pulse desiccation and specific timings for Sharpen use on your farm.

Article produced by - Sam Gabbe, Western AG - Horsham

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