Several points I would like to mention:

(point 1) "Soils with higher amounts of clay and organic matter have more potential for herbicide carryover than coarse-textured soils or those with less organic matter. Higher amounts of soil organic matter and certain types of clay particles increase the potential for herbicide carryover by adsorbing more herbicide onto these soil colloids. Herbicide bound to soil colloids is not available for plant uptake, movement downward through the soil profile, or microbial degradation. Injury to rotational crops is possible if these bound residues are displaced by water molecules either late in the season they were applied or the following spring."
H.Kuska comment: Most/all? rose beds probably qualify as "high organic".
-------------------------------
(point 2) "Soil microorganisms are responsible for the degradation of many herbicides. The composition of microorganisms (species and abundance) in a particular soil influences how quickly herbicide degradation occurs."
H.Kuska comment: those who regularly spray with powerful synthetic fungicides probably have very little soil microorganisms as the "soil microorganisms" are often also fungi.

With all due respect, I find myself somewhat disgusted by this kind of post. It refers to "rotational crops" which implies a usage far greater than that of most home gardeners which makes the information distorted for home gardeners.

For a dose of reality .. if I find poison oak cropping up between my roses, I am going to put a dark plastic bag over the poison oak plants while wearing very thick plastic kitchen gloves, cut it at the stem, wash it with alcohol and paint it with Round Up. The last time I caught poison oak, I landed in the hospital.

The amount of Round Up that enters my soil is quite small compared to that used for a "crop". I'd much rather take the risk of losing rose or two than to land in the hospital and pay my portion of the hospital fee.

I love that you share information, but please use some common sense and make it applicable to the home gardeners who use this forum. That would make your information of value to most of us.

With Regards,
Lyn

Concerning your procedure for treating Poison oak: The Roundup label recommendation is to treat the intact plant with the herbicide. That way, the herbicide is absorbed by the leaves and transferred to the roots, and completely kills the plant within a couple of weeks. Your procedure of first cutting the plant at the stem does serve the immediate purpose of making your garden safer for you but you might point out that it is not the surest way to kill a plant with Roundup.

"Planting the same crop next season as in 2012 would effectively eliminate the potential for crop injury from herbicide residues."

Luckily, I had the crop dusters avoid my backyard this year and I'm not planning on rotating soybeans into my rosebeds.

Also keep in mind that as of last weekend, we've sustained damage to 2/3 of the corn crop in Illinois and about 50% of the farmers in certain Western & Southern counties had already decided to raze the corn crops. Instead of spending time & money harvesting a disaster, they are simply mowing down their corn.

Mike... I usually catch the poison oak plants when they are quite small in the rose beds, but once in a while I do find a larger plant up on the slope of my property. In that case, I leave the plant covered with black plastic for a week or so and let the heat in my climate, along with the lack of light, cook it to death . Poison oak emits a sap as soon as it is cut. Using the alcohol to remove that sap before applying the Round Up allows the herbicide clean and certain contact with the plant stub and this method kills the plant the first time, every time, with no chance of wind drift to nearby plants.

I've done it for years and have never had to go back an retreat a plant. Nor have I damaged any nearby plants.

If I don't remove those plants, my cat is always quite kind and brings poison oak oils to me on his fur.

It's always something.

Smiles,
Lyn

That was interesting information, thanks.

Mike

It's a valid question. Poison Oak is either a shrub or vine. I have found that it does not have a tap root, but even a small plant can extend roots underground over a very wide area. If those roots are broken, a new plant emerges. With my extreme allergic reaction, that's why I want all of those roots totally dead.

Yes, the poison oak roots can invade the root system of a near by rose. Here's where I have to make a choice. Do I risk losing a rose or do I risk going to the hospital ? For me, it's a no brainer. I hate hospitals and in this economy paying savings back is much more difficult than replacing a rose ... even if that rose is no longer in commerce. I have a list of over 100 roses I want to try, but not enough room in the garden.

I only use Round Up on poison oak. My preferred weed removal method is the aching back kind of thing of hand removal and proper mulching.

Kippy ... I know of one, and only one, incident of rose rosette virus being found in California. It was on one stand of r. pisocarpa which happens to be native to my part of California. That reported incident occurred more than 50 years ago and there has not been another reports since then. Trust me, they have been looking for a repeated incidence.

Smiles,
Lyn

http://www.agron.iastate.edu/news/events/2011staniforth_sm.pdf
(in particular see page 19 and 20 for Round-up spread)

The following published scientific research indicates that glyphosate could remain bound for long time periods:

"Glyphosate [(N-(phosphonomethyl)glycine)] is a widely used herbicide and it is known to compete for the same sorption sites in soil as phosphorus. Persistence and losses of glyphosate were monitored in a field with low phosphorus status and possible correlation between glyphosate and phosphorus leaching losses was studied. Glyphosate and its metabolite AMPA (aminomethyl phosphonic acid) residues in soil samples were analysed after a single application in autumn. Twenty months after the application the residues of glyphosate and AMPA in the topsoil (0�25 cm) corresponded to 19% and 48%, respectively, of the applied amount of glyphosate, and traces of glyphosate and AMPA residues were detected in deeper soil layers (below 35 cm). These results indicate rather long persistence for glyphosate in boreal soils."

http://www.springerlink.com/content/w1461w60366lk018/

Then, when you add fertilizer with P; the glyphosate could be released.

"The results suggest that re-mobilisation of glyphosate may represent an additional transfer pathway for glyphosate to non-target plants which is strongly influenced by soil characteristics such as P fixation potential, content of plant-available iron, pH, cation exchange capacity, sand content and soil organic matter."

http://www.springerlink.com/content/t7h6601566432076/

------------------------------------------------------------

My soil is heavy clay. I spray on weeds that are sometimes right next to (within inches) of roses. I spray at whatever time of the season I need to (i.e. year round), but normally that's only 2-3 times a year. I water with drip irrigation. I use fungicides like Banner Maxx and Mancozeb every two weeks.

It appears that you are relatively safe in heavy clay. It is my assumption that most rose growers grow their roses in organic soil beds (even if the surrounding ground is clay).

The following very recent paper is available in full free. The historical review in the introduction should be useful as an indication as to what is now known about glyphosate damaging nearby plants.