It depends on where the roses originate.
If it's a different part of the country, I keep them separate for two or three weeks.
So far, I've kept out Rust and a nasty green caterpiller that way.
I also worry about bringing in different strains of Blackspot, Midge, etc.
Right now, I also worry about ignorant folks buying plants in south Florida (not necessarily roses) and bringing chili thrips into my part of the country. Especially snow birds who overwinter down there and then drive their RVs north for the summer. And then they put their tropicals out ....

All we can do, really, is try to keep our gardens clean. And if something bad comes in, call the ag. people so they can react. (County Extenision Agent, State Ag inspectors.) Odds are that the problem won't originate with us but will migrate to us from someone who doesn't pay attention.

And, yes, I have neighbors who take their honking big RVs way south for winter.

I personally believe that I imported rose midge via a potted rose. I cannot identify the vendor beyond any doubt, so don't even ask. I just don't order from those suspected vendors any more.

Quarantine is the only way to be certain that you don't import something you don't want.

Barbara
PS: I'm still battling midge. This is my fifth year.

I remove the soil, bag it up, and put it in the garbage. I rinse the roots off and replant in new potting soil.

Wow! This is an eye opener. I never really thought about it before. I guess I've been lucky. I'll treat any future purchases differently now.

AFter I posted this question I thought about Chili thrips too. HoovB, your solution really sounds good..non-toxic and effective for anything in the soil. I do think midges lay eggs inside plant tissue though, so I am wondering whether a systemic poison on new plants might be wise. I am paranoid about midge after reading about it. I don't know whether Bayer would work on midges in a contained area or not.

Before I ever got interested in roses I read that it was a good idea to quarantine new plants to prevent the spread of stuff like whitefly. Ann, do you think Chili thrips would survive our winters?

Linda

Linda,
Right now, I don't know what their northern spread potential is.
But I remember from Houston finding all kinds of bugs alive in my wood pile when the temps dropped to 20 for five days one winter...and I really thought they'd be knocked back. It just slowed them for a few days.
The real problem with chili thrips is that they like so many different plants, that all they might need is the bark of something that makes thick loose bark....
Or in some plant that makes a fruit with a little built in 'antifreeze' (rose hips) because I've found rose hips in the leaf litter in March that survive winter with no damage.

We don't have powdery mildew. And because we don't it really lays the roses out and I'm stuck with it all summer until it gets cold again. So I get things delivered to my shop in town and spend two weeks spraying them before I take them home.

Linda, interesting what you said about midge remaining in rose tissue. Do you have any further thoughts on that? The bayer pesticide for trees is the one most widely recommended for rose midge when used as a soil drench. It also kills everything else, but in a container would be the best place to use it.

Ann, I guess bugs are nothing if not adaptable. Hope not to see any Chili thrips..I think I heard they can come home with you on fresh produce.

Barbara, I know very little about midge. I think their life cycle is very short, so they wouldn't remain in plant tissue for long. The way I understand it, the eggs are laid in stems below buds and it's the tiny maggots that do the damage. Then they drop to the ground and finish developing there. Sounds like one could try to eradicate them systemically while in the plant, by contact in the ground, or while they're flying around. Have you seen them in the flying around stage? I've been reluctant to use any drench on my new arrivals but it makes some sense to me, especially since I've heard that certain parts of the country have had huge midge problems.
Linda

Linda, I really cannot say I have seen them; they are so small. Everytime I see a knat like bug-meaning very tiny-flying I try to kill it. I think one needs a microscope to detect larvae. What I've been doing in lieu of soil drenches with pesticides is breaking off new growth that looks suspicious. I cannot even say with any degree of certainty that I've prevented new midge in this effort. Without spraying pesticides, there are very few alternatives to eradicate.

Barbara