Crop desiccation

It may correct for uneven crop growth which is a problem in northern climates, during wet summers, or when weed control is poor.

True desiccants do not often provide good weed control because killing only the top growth may allow plants to begin re-growing again.

[16] In contrast, Photosystem I inhibitors such as diquat and paraquat work by entering plant cells and immediately diverting electrons away from photosynthetic chain, poisoning photosynthesis.

[17] Contact herbicides used for desiccation include: carfentrazone-ethyl, cyclanilide, diquat, endothall, glufosinate, paraquat, pelargonic acid / ammonium nonanoate, pyraflufen-ethyl, saflufenacil, sodium chlorate, thidiazuron, and tribufos.

As a systemic herbicide it is not a true desiccant as it can take weeks rather than days for the crop to die back and dry out after application.

[23] Yield may be affected and residues increased if applications are made to uneven fields in which some areas have a moisture content over 30%.

Although used in weed-free and evenly maturing crops with the aim of reducing the grain moisture content more rapidly to hasten the harvest, there is little or no advantage in doing so.

In North America, for example, its use on wheat crops is uncommon in the United States but more common in Canada which has a colder climate and shorter growing season.

In the UK where summers are wet and crops may ripen unevenly 78% of oilseed rape is desiccated before harvest, but only 4% in Germany.

[27][28] Glyphosate was found in 5–15% of cereal crop samples tested in the UK between 2000 and 2004, although never exceeding the Maximum Residue Level of 20 mg/kg.

[30] However, the German government's Federal Institute for Risk Assessment made an official comment that those levels did not pose a risk to consumer's health, emphasizing that “An adult would have to drink around 1,000 liters (264 U.S. gallons) of beer a day to ingest enough quantities to be harmful for health.” An industry group, Brauer-Bund Beer Association, asserted that the results weren't credible because of insufficient sampling and that its own monitoring system for malt never detected glyphosate levels above maximum permitted levels.

Separately, in 2020 scientists from the Max Rubner-Institut published a study about correlations between trace levels of glyphosate in human urine with consumption of various food types.