Should you swath ?? Or desiccate your crop?? Or what about weed control in your crop?? This article will discuss the advantages and disadvantages of Pre-Harvest glyphosate and desiccation with Reglone.
Firstly, let's look at the differences in the two operations. Pre-harvest applications are geared for control of perennial weeds such as quack grass, Canada thistle, sow thistle and dandelion. These weeds are of increasing importance in direct seeding systems. The late summer timing is especially effective for Canada thistle. Canada thistle is most vulnerable to a glyphosate application at the bud stage. At this stage, the root reserves are at their lowest, translocation to the roots is rapid and the plants have a large leaf surface to absorb the chemical.
Preharvest may also aid in crop drydown and evening of maturity. This, however should not be the major reason for using this tool. The speed at which the crop will die down is very weather dependant and a period of cool, wet weather following application can still result in a 2 week + interval until the crop is ready to harvest.
Desiccation with Reglone on the other hand, is used specifically to aid in the rapid drydown of crops. The use of a desiccant will speed up the natural drying of a crop and allow for earlier, easier harvest of the field. Desiccation will not, however give you anything more than top growth burndown of perennial weeds.
Pre-harvest Glyphosate
Note: All glyphosate products are not registered for preharvest applications. Please consult specific labels for application recommendations.
Glyphosate should be applied at 1 L/ acre. Water volumes should be a minimum of 5 gallons of water. The use of 10 gallons is recommended in situations where heavy crop canopies exist and where control of dandelions is being targeted. Application should be made under low wind conditions as glyphosate drift can cause significant damage to neighbouring crops, gardens or shelterbelts.
The proper timing of application of glyphosate is important as too early an application may result in reduced yield and an application too late will give less harvest management benefits. Consult with Monsanto for per staging of the various crops.
All crops that are normally fed to livestock as seeds, crop residues (straw and chaff) or screenings are cleared for use as crop feeds. Label rates and intervals to harvest must be followed.
It is not recommended that seed from fields treated with glyphosate in a preharvest application be used for seed. While work has been done that indicated that applications at or after the 30% moisture level of crops does not effect germination, seed labs are consistently able to detect seed lots treated with glyphosate by germinating seeds exhibiting poor and distorted growth. This may result from the fact that most fields have depressions where maturity is delayed. These areas will have moisture above 30% when the majority of the field is at or below 30% and the field is treated.
Glyphosate should be applied two hours prior to a rain for maximum effectiveness. Roundup Transorb has a rainfastness of one hour.
While some glyphosates are registered for use on malt barley, some maltsters are reluctant to accept barley treated with glyphosate. Check with your elevator or malt plant for details on restriction. If you choose to apply, ensure that the least ripe area of the field has reached the 30% moisture level.
Dessication with Reglone
Reglone should be applied at 0.6 - 0.8l / acre in a minimum of 10 gallons of water. The use of higher water volumes is recommended in situations where heavy crop canopies exist. The higher rate should be considered when heavy weed growth exists. The use of the surfactant AGRAL 90 or Agsurf is required to be added at 0.1% of spray volume (1l / 1000 l of water) for maximum results. As Reglone is a contact herbicide and is not translocated, the better the coverage, the better the effects of Reglone will be.
Too early an application may result in reduced yield and an application too late will give less harvest management benefits. Again consult with Syngenta.
Argentine Canola should not be treated with Reglone unless the crop is severely lodged. Losses due to shattering can result.
All crops that are normally fed to livestock as seeds, crop residues or screenings are cleared for use as crop feeds.
If applied at the proper stage, there is no adverse effect to Reglone-treated crops used for seed.
An interval of 15 minutes is required between application and rainfall for best results.
Notes: When heavy crops are encountered or where weed density is high, the application of Reglone under cloudy conditions or in the evening will result in increased efficacy and quicker drydown. Water volumes and application rates under heavy canopy will also increase the effects of Reglone.
Utilizing the tools that are available can help you manage valuable harvest time as well as optimize weed management.