Monday, 6 August 2012

Pre Harvest Glyphosate and Desiccation

Lentils are the main crop that will get hit with Reglone (diquat) and I will touch on them first. Ideally the staging is so that the lowest third of the plant pods are rattling and the seed itself is hard and doesn’t split, the middle third of the plant will be hard and not juicy, but will split nicely into 2 halves and the top third will be full size, but immature. This is also the proper stage for glyphosate timing. The MRL of glyphosate did get increased to 10PPM (same as peas) this year so you are able to use glyphosate if you wish. Be aware glyphosate is NOT a desiccant. It will kill the plants, but it does very little to increase dry down like Reglone will. A glyphosate app still means you could have 10-14 days or more till the proper harvest timing, where as 4-7 days (can be 10) is typical time from Reglone app to harvest.

Peas proper staging for Reglone/Glyphoate is the bottom third of the pods will have seeds detached and rattling with the pods being translucent and shrunken, middle third will have shrunken and leathery pods and will split when squeezed, upper third will just be starting to turn. Again, glyphosate is not a desiccant and will only speed up harvest by a few days or so vs. no glyphosate.

When it comes to using Heat (saflufenacil) from BASF there is no MRL set and I would suggest to avoid using it if you can to save yourselves from having to deal with a buyer denying your lentil crop. If you do decide to use Heat be aware that it will not be as effective as Reglone, atleast not in my experience. You also must use an increased rate as opposed to the 10.4g/ac (80ac/jug). You should use atleast 14g/ac and ideally use upwards of 20grams per acre (40ac/jug) to see better results.

Aim (Carfentrazone) from Nufarm is also registered as a desiccant. You have to increase the rate significantly to get the results you want. In my experience it is a product that will still get the job done if you decide to go this way.

For wheat and barley(not malt) timing of glyphosate, you are looking at close to the same time as swathing. The wheat and barley will be at 30-35% moisture, or hard dough stage. A finger nail imprint will remain on the seed. You can get away with maybe 2-3 days before a typical swath timing would be, but remember if you go in to early with glyphosate the seeds will appear shrunken and it will have a similar appearance to frost damage. In wheat you may also look at the peduncle which is the stem located just below the head, and it will have turned from green to a brown colour.

Remember glyphosate is much better on perennials so if you have a field with lots of quackgrass, Canada thistle etc. then using glyphosate is your best route to go. Not going to be effective to tank mix them, but if you want to get the best of both worlds then using glyphosate first and then hitting with Reglone 3 days later is probably your best bet to get dry down and good perennial weed control.

Some notes on Reglone:

-Reglone prefers water pH of <7

-Ideally use 15-20 gallons of water per acre, the more the better.

-Doubling up on surfactant can be very effective to ensure chemical penetration into the plant.

-Be sure to increase PSI to above 50

-I have heard mixed comments on nozzles, Twin TurboJet seem to be a good option though.

-LI700 is a surfactant that helps get the chemical into the plant as well as lower pH, seen good results with it. Rate is 0.1% v/v, 0.2 if you want to double the rate. Note: Syngenta wants 0.25% v/v to support this adjuvant use.

-If you are using an AgSurf product for example then it is reccomended to double it.

-Reglone is a contact that reacts off UV light so spraying in the evening allowing the chemical to get into the plant is a very effective route to go. This means it is fully soaked into the plant for the next morning/day. You may get some slight local systemicity vs. straight contact as well if sprayed at night due to it soaking in a bit better within the leaves.

-Very rainfast, 15 minutes.

-Reglone prefers hot temperatures so if you can time it so that you spray in the evening and the next day is HOT, it will be more effective.

-Reglone is a group 22, this can be an effective chemical to change up herbicide groups in your rotation.

-The rate is 0.7-0.8L/ac typically, heard of guys going 1L/ac. My main tip with the rate is don’t assume that since you are going the high rate you can cut the water volume, in my experience going the lower rate with higher water volume is MUCH better than going high rate with a low water volume.

It has been a while since my last blog post, hopefully I shook the rust off and wrote one that some get atleast a little bit of info from.

If you have any questions or comments feel free to ask.

Sources: Syngenta Canada


  1. Can you elaborate on the reason Reglone/ Glypho tank mixes are not effective? Is the uptake mechanism changed? Does the mixing of either reduce effectiveness of both? Thank you! Another good post!

  2. Got it cased,
    "When the plants were evaluated to determine the amount of chemical they retained and how the chemicals were distributed in the plant, the numbers indicated a clear result. When glyphosate was applied alone, a large portion (63.7 percent) was recovered within the tissues of the treated plant. But more importantly, 39.9 percent of the applied glyphosate was also found in other parts of the plant, proving that translocation had taken place away from the treated leaflet. However, when the glyphosate was combined with diquat, 78.5 percent of the applied chemical was recovered in the treated area of the plant but only 6.1 percent was recovered away from the point of entry. The researchers found the net result to be a substantial reduction in the translocation away from the point of entry when diquat was used in combination with glyphosate."
    Source's Source:

  3. Thanks for the comment. The Reglone will work fine, but since the Reglone works so fast, the plant fails to uptake and properly translocate the glyphosate efficienctly enough through the plant. This means you will not systemically kill the plant and there is potential for regrowth. This is mainly true on perennials and winter annuals. Hope this makes sense.


  4. Thanks for posting that, thats a great explanation.