Depends on which rugosa. My Rosa Rugosa Alba REALLY resents spraying. If some of the spray intended for another rose blows over and gets on that plant anywhere, it shows up in about a week as a dead place on the leaf or leaves that caught the drift. On the other hand, my Moore's Striped Rugosa gets sprayed the same as any other rose I have, and it doesn't need it, but it also doesn't care one whit. Nothing happens to that rose if sprayed, accidentally or on purpose.

Kathy

The black spotted yellowing leaves are the result of a blackspot fungus, not from spraying insecticide. I believe spraying an insecticide on a rugosa will result in killing any bug present on the bush. On the other hand, spraying a fungicide will result in crispy dry leaves which means you'll have no blackspots or yellow leaves. How the soil drench type systemic products from Bayer affect a rugosa, I don't know, but if you try them let us know the results.
With tent caterpillars, I cut off the web mass and burn it. When I get blackspotted yellow leaves on any rugosas, I pull them off or they'll quickly fall off of a badly infected bush leaving me without the blackspotted yellow leaves.
In other words, I don't get excited!

About 29 years ago gypsy moth caterpillars became so bad here that they had to do plane spraying for them. They wiped out entire mountain ranges and were impacting a very large area. Leaves were striped from trees for miles and miles.
They were here for a few years, then disappeared and we haven't had trouble since then. (knocking on major wood!)

Actually only oil based fungicides damage rugosas. In my eperience you can spray, for example Banner Max, on ANY rugosa including Alba and Rubra w/o any ill effects. I never spray insecticides, so no knowledge here, but I would assume the same principle applies.
Olga

Not so for me. I don't use oil based fungicides. Usually it is Compass or Banner Max and sometimes Cleary's or Mancozeb (and usually I put a little Response fertilizer in there too). All of those adversely affect R. Rugosa Alba here. I also rarely use insecticides, so what effect they may have is also beyond my knowledge and experience.

Kathy

I try to avoid spraying, but I think the chemical Imidacloprid is well tolerated on rugosas. Be extra careful that the sun is setting before you spray the plants because they are extra sensitive that way. I have a couple of times had problems with leafhoppers that did major damage to the leafs, and it worked well.

I haven't used fungicide on rugosas, but I have used Bayer Insect Killer for Japanease beetles. Repeated use resulted in diseased-looking leaves that turned brown and fell off.

Kathy, you probably have residual Mancozeb or Cleary's in your tank. They do affect rugosas, but Banner itself, no:) I swear. I tried it even when it is 90+ outside
Olga

If you are considering using an Imidacloprid based spray, you may find the following article of interest:

http://minnesota.publicradio.org/display/web/2010/05/28/pesticides/

I had a Pink Grootendorst, and if spray strayed onto it, the leaves turned brown, shriveled, and became crispy as if burned. I had to be very careful when spraying to avoid this.

Oh I see Henry. It's a few years since I've sprayed with anything other than organic remedies, thanks for the tip. I actually think the current substance is called Thiacloprid, sold as Calypso here.

Apparently, thiacloprid is on the radar regarding honey bees also.

http://www.extension.org/pages/Pesticides_Applied_to_Crops_and_Honey_Bee_Toxicity

There ia a new EPA docket regarding thiacloprid:

"Federal Register Notice: Thiacloprid - Pesticide Products; Registration Applications - EPA has established a docket for comments for this chemical. EPA-HQ-OPP-2010-0311 "

But, apparently the site is down for the weekend.

I thought the damage looked just like Black Spot, but my other roses weren't affected . . . and I've never seen Black Spot on any of my rugosas before.

The rugosas I sprayed were Blanc Double de Coubert, Dart's Dash, and Wildberry Breeze. Dart's Dash in particular got a heavy spraying because it was literally covered in caterpillars. But the one one that seems to have suffered from the spraying is Wildberry Breeze. Or maybe something else is causing the problem.

I was surprised that I only had to spray once; the caterpillars have stayed away from these plants ever since.

Thanks for your input!

Susan

Thanks again Henry. The best way is probably not to spray at all. Regarding the deaths of bees, I read a theory suggestning it has to do with mono-cultures, patented seeds/geneticly modified, disturbing the natural diversity directly linked to bee-health. Moving bees from field to field could alo impact their health, because of excess stress.

Alisande, last year I sprayed three with organic insect control when I had a massive infestation of rose slugs on my brand-new roses. Chapeau de Napoleon, Queen of Denmark and Reine des Violettes all got sprayed and every one of them protested loudly. They all got severe leaf burn, and RdV even dropped about a third of her leaves. This year they are fine except for RdV, which perished in her pot over winter. RIP.

LOL, Taoseaker, Henry will direct the entire nuclear arsenal against every synthetic spray and will quote a source of "evidence" even if that is the only source and there is ten or hundred other scientific evidence against that one quoted source. In my experience it depends on when you use Imidacloprid based sprays. But I guess faith has much more to do with this issue than science.

ceterum, please give your "ten or hundred other scientific evidence against that one quoted source" that refute what I have found. This is a forum.

Regarding what the reviewed published scientific literature says about bees and imidacloprid. When a scientific paper is submitted for publication, it is the responsibility of the Editor and the reviewers to see that the paper adequately and fairly covers the prior published literature.

Here is a very recent reviewed scienific research paper from a European source.

Title: Risk assessment for side-effects of neonicotinoids against bumblebees with and without impairing foraging behavior.

Authors: Mommaerts, Veerle; Reynders, Sofie; Boulet, Jana; Besard, Linde; Sterk, Guido; Smagghe, Guy.

Authors affiliation: Laboratory of Cellular Genetics, Department of Biology, Faculty of Sciences, Free University of Brussels, Brussels, Belg.

Published in: Ecotoxicology (2010), 19(1), pages 207-215.

Abstract: "Bombus terrestris bumblebees are important pollinators of wild flowers, and in modern agriculture they are used to guarantee pollination of vegetables and fruits. In the field it is likely that worker bees are exposed to pesticides during foraging. To date, several tests exist to assess lethal and sublethal side-effects of pesticides on bee survival, growth/development and reprodn. Within the context of ecotoxicol. and insect physiol., we report the development of a new bioassay to assess the impact of sublethal concns. on the bumblebee foraging behavior under lab. conditions. In brief, the exptl. setup of this behavior test consists of two artificial nests connected with a tube of about 20 cm and use of queenless micro-colonies of 5 workers. In one nest the worker bees constructed brood, and in the other food (sugar and pollen) was provided. Before exposure, the worker bees were allowed a training to forage for untreated food; afterwards this was replaced by treated food. Using this setup we investigated the effects of sublethal concns. of the neonicotinoid insecticide imidacloprid, known to neg. affect the foraging behavior of bees. For comparison within the family of neonicotinoid insecticides, we also tested different concns. of two other neonicotinoids: thiamethoxam and thiacloprid, in the lab. with the new bioassay. Finally to evaluate the new bioassay, the authors also tested sublethal concns. of imidacloprid in the greenhouse with use of queenright colonies of B. terrestris, and here worker bees needed to forage/fly for food that was placed at a distance of 3 m from their hives. In general, the expts. showed that concns. that may be considered safe for bumblebees can have a neg. influence on their foraging behavior. Therefore it is recommended that behavior tests should be included in risk assessment tests for highly toxic pesticides because impairment of the foraging behavior can result in a decreased pollination, lower reprodn. and finally in colony mortality due to a lack of food."

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I have a copy of the full paper but I can only post the abstract due to copyright restrictions. However, I can send a limited number of copies of the full paper by e-mail "for educational purposes" if anyone desires to read the full paper.

I can also quote a section (or sections) to make a point in a discussion. Here is some of what the autors cite about the research that had been previously published on the subject:

" To date, most studies on bees mainly consider mortality (Suchail et al. 2000), while less attention is given to sublethal effects which may be detrimental towards pollination and subsequent bee populations. Thompson et al.
(2003) and Desneux et al. (2007) reported that sublethal
effects must be considered when evaluating the impact of
pesticides on pollinators. To date, multiple laboratory
studies have focused on the impact of pesticides on the
biochemistry of honeybees (Armengaud et al. 2000).
However, interpretation of the negative effects on the
neurophysiological capacities of insects is difficult, and in turn the effects for the insect or the whole colony are
unknown. For honeybees the proboscis extension response
(PER) assay has been used to determine the impact of
pesticides on the learning ability (Lambin et al. 2001;
Decourtye et al. 2004a; El Hassani et al. 2008). Further,
Decourtye et al. (2004b) showed the reliability of this
method to detect disturbances at the level of the learning
behavior on free-flying foraging bees under more natural
conditions. For honeybees such abilities are essential
because they rely on their visual learning capacity to
communicate the distance and the direction to the food
source. Pesticide exposure to honeybees while foraging
could affect their orientation behavior (Vandame et al.
1995; Bortolotti et al. 2003; Thompson 2003; Yang et al.
2008). In France, it was believed that honeybee mortalities
in areas of sunflower crops were linked to the use of pesticides (Bonmatin et al. 2003). This assumption was not
supported by Schmuck et al. (2001), who found that the
residues in pollen and nectar of sunflowers were too low to
be detrimental. But in the field, bees can be chronically
exposed to pesticide residues via contaminated stored food
(Schmuck et al. 2001; Bonmatin et al. 2003; Miranda et al.
2003; Chauzat et al. 2006). Numerous studies have reported
that ingestion of small quantities can lead to sublethal
effects in honeybees (Colin et al. 2001; Decourtye et al.
2003); in laboratory and semi-field tests it was reported that low concentrations of imidacloprid taken up via the pollen were responsible for changes in foraging and food collecting and for the loss of ability to communicate and learn (Colin et al. 2001; Decourtye et al. 2003). Similar sublethal effects on the learning ability were found after exposure to fipronil (Desneux et al. 2007), on the communication dance by carbamate insecticides (Thompson et al. 2003) and on the homing flight by the pyrethroid insecticide deltamethrin (Vandame et al. 1995; Ramirez-Romero et al. 2005). Until now, most studies have been performed on honeybees, while other bees like bumblebees may also be affected by pesticide poisoning."
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The link below leads to a full 2010 paper that discusses the imidacloprid/bee situation.

http://www.bulletinofinsectology.org/pdfarticles/vol63-2010-153-160maini.pdf