What is the difference between these two? Which would be more effective for burning down some foliage for planting food plots? Would it be effective to use them together? I intend to use Sean's spray/seed/now method for this.

Fair to say that you have to soak the whole plant to get a good kill with diquat while glyphosate would kill with less contact?

Horse with No Name said:

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Fair to say that you have to soak the whole plant to get a good kill with diquat while glyphosate would kill with less contact?

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No, diquat wont kill the roots no matter how much you apply.

Diquat is also nastier than glyphosate to handle as an applicator.

It's really not even a comparison in my mind. Use glyphosate as your burndown and move on.

I can't imagine any advantage to Diquat. For burning down a food plot, use glyphosate mixed with a little 2,4-d, and don't spare the surfactant or water.

Diquat/Gramoxone has been a good burn down for my guys before planting soybeans or cotton in northeast Texas. But, if they have more grassey weeds, glyphosate is a better choice. If it's henbit or other broadleaf weeds, Gramoxone/Diquat have worked

Thanks for all the replies. I sprayed roundup yesterday, so no going back now. I am always interested in learning for next year, though.

The reason for the question is that I don't necessarily want to kill the cover off and have bare ground when the annual food plot is played out. Second question is efficacy in burning down grass and weeds that are 2-5 feet high while using a hand sprayer. Finally, speed of killas stated, glyphosate takes a while to kill.

I'm interested in knowing about the comment regarding danger to the applicatorHow bad is the stuff, and does it stay active for any amount of time in the soil?

Inert and safe on the ground.

But there is a reason that Gramaxone and other chemistries in that herbicide class have an actual Skull and Crossbones on them. You are fine, but actually follow the directions.

Horse with No Name said:

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Thanks for all the replies. I sprayed roundup yesterday, so no going back now. I am always interested in learning for next year, though.

The reason for the question is that I don't necessarily want to kill the cover off and have bare ground when the annual food plot is played out. Second question is efficacy in burning down grass and weeds that are 2-5 feet high while using a hand sprayer. Finally, speed of killas stated, glyphosate takes a while to kill.

I'm interested in knowing about the comment regarding danger to the applicatorHow bad is the stuff, and does it stay active for any amount of time in the soil?

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If the weeds were that tall, you might be disappointed with glyphosate alone. That's where the 2,4-D comes in.

Soil = negative charge. Diquat = cation. No soil residual whatsoever because its irreversibly bound to the soil particles, especially higher clay content soils (more surface area, so more anions to bind to).
Diquat is a cell membrane disruptor and inhibits a process in photosystem 1. Thats why you can see rapid activity on bright days when photosythetic rate is high, i.e. there's alot of photosynthetic activity, so theres alot of photosynthetic activity to inhibit. It does not translocate, but with adequate coverage, gives a rapid burndown, and good control.
This is one that does have some bad traits though. Its highly corrisive to metals, highly corrosive to eyes, and can be rough on the lungs if inhaled as fine droplets. Its a good herbicide for its intended purpose, as long as used with some caution. But I've also seen it eat holes in an aluminum boat in under an hour.
Its cousin is paraquat (Gramoxone). Like previously stated, its a rowcrop burndown herbicide. Where I'm from, they apply it on beans at maturity to quickly dry the plant down to facilitate early harvest. Rapid results. I'm not scared of exposure to most of the herbicides out there. I'm scared of paraquat.

I have never used diquat but I use a lot of paraquat. If it is annual broadleaves only and you want them DRN (dead right now) paraquat is the ticket. AMS, 1.5x water, NIS, spray in the evening after 5, coverage is key and dead in 24 hrs. If it is annual grass or perennials, use glyphosate. I never mix the two because they work against one another. If you want to enhance paraquat activity add 1/4# atrazine, assuming that doesn't affect the species you are planting afterward.

While I was spraying the glyphosate I noticed that much of the grass was fully headed out with dry seed above green foliagedo any of the chemicals discussed kill the seed or leave it viable?

Ideally, I'd be able to burn down the grass, but leave the seed to regrow next year.

Horse with No Name said:

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While I was spraying the glyphosate I noticed that much of the grass was fully headed out with dry seed above green foliagedo any of the chemicals discussed kill the seed or leave it viable?

Ideally, I'd be able to burn down the grass, but leave the seed to regrow next year.

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If the seed is fully mature, Roundup won't hurt it.