I doubt here is much relationship between disinfecting your pruners and the development of blackspot. That is a primarily a foliar fungal disease and tends to be heavily weather related. Lack of air circulation will encourage it as well as high humidity, plentiful rainfall and moderate temperatures. You could get some spore transference from pruners but not enough to cause a "severe outbreak". But if you live in a climate that offers the conditions cited above, you can pretty much guarantee blackspot unless you engage in preventative spraying.

Gardengal is correct. You live in Florida blackspot is a constant problem in your area and it has nothing to do with your pruners. I live in a similar humid warm place and blackspot is my major concern when growing roses. What kind of roses are you growing? In order to keep blackspot under control you have to spray or choose very blackspot resistant roses. Cleaning the pruners and the plant debris is always helpful, but will not solve the blackspot issue in such a high pressure area.

I agree with dianela7bnorthal. You will need to spray a fungacide.... and it is best to have two different kinds such as Heritage and Clearys333 or Bayers.... and mix it with Mancozeb Flowable with Zinc.

I also use Cleary's and Bayer spray. Next year begin spraying as soon as the first tiny leaves appear and continue spraying regularly at least until the first bloom cycle is done. Then spray occasionally the rest of th e summer. You MUST get out ahead of it early.

Emily:

Though the premise prompting your question is not correct, no one here even attempted to answer your question. They may have overlooked it in a rush to comment. Or maybe because the question mark was missing.

So I will answer it.

yes

https://en.wikipedia.org/wiki/Hydrogen_peroxide

I really appreciate these responses and have learned several things:. start spraying when first leaves appear, be consistent with your spraying routine, etc. However, I now have all this black spot to deal with and wonder what to do to stop it from getting any worse and infecting my other roses. Thank you and please keep your comments coming.

the key is: an ounce of prevention.. is worth a pound of cure .... if in fact.. there is a cure in any given season ...

an analogy is fruit you see in the store ... to get that pretty fruit ... there is a cycle of 3 to 5 sprays starting in later winter dormancy .. thru the whole growing season ... and this is why.. many hobby backyard fruit peeps fail .. since they dont do it ... they may get edible fruit .. but it might not be pretty ...

remember.. full fall cleanup .. and then start spraying.. before you have a problem ...

ken

Emily while preventing is the key you can certainly go ahead and start spraying now. The leaves already infected will not recover, but they will fall and the new leaves with be green and beautiful. How many roses do you have? It would probably make a difference whether you have 10 or 100 on the best approach. If you only have a few bushes you can remove every single infected leave and dispose of them in the garbage then spray everything that’s left every other week. Your new foliage will be perfect. Please spray very early in the day or very late so you don’t take the risk of burnig them.

I have around 200 roses. It's in the 90s where I live so I've waited til late a'noon to spray. Been using Bayer and baking soda alternately.

Yes, if you continue to spray now, you can prevent the disease from spreading to uninfected foliage. But it must be done very routinely - every week to 10 days or as the fungicide label directs.

Ok 200 is a solid number to remove all the infected leaves by hand so you can skip that step, unless you have a lot of time. I stopped doing the manual removal probably after the 50 mark because it was just too much to go around every single bush. I have close to 400 now and I do defóliate in winter but only after heavy pruning them. I would rotate the Bayer with any other product that has a different ingredient like Daconil. I would skip the baking soda and add the other product to the rotation. I have used baking soda and milk and other products for mildew but they don’t work here for blackspot. Hopefully all your new foliage will come back great. 🤞. Also unless you have been getting torrential rains like my family in south Florida, give them some extra water if you can, they are probably feeling pretty hot by now in Florida.

How do you "defoliate" after heavy pruning in winter?

I prune my roses to around 2 to 3 feet in the winter and then by hand pull off every single leaf. I dispose all of the foliage in the garbage and this allows my roses to built brand new foliage when spring comes. This is a very common practice for many people in this forum, but since you are in Florida I am not sure how much of a winter you would actually get or when you should do it there.

Like this- completely clean to begin a new season

Roses 2019 · More Info

then spring comes and everything is new. those who live in cooler zones probably get natural winter removal of all their leaves, but here I have to do it or I would have some left. The point is to get rid of a lot of the infectious spores that will be on that old plant material. I hope this helps.

I grew roses in S.E. and Central Fl. for 40+ years. If you want certain types of roses, you need to spray a fungicide on a regular schedule. Even now that I'm retired and living in N.E. GA. I spray my roses with Bayer Disease Control every 2 weeks to keep everything clean.

When was the last time you fertilized.....

Here in South Florida I am zone 10...

I found through my rose society that I needed to be fertilizing more in the summer.... but not with a granular synthetic because that encourages chili thrips.... I now fertilize once a month with Sul--Po- Mag (Kmag) and milogranite. I have found this helps because my roses are not so stressed in the summer.... it will NOT replace spraying a fungacide, but should help in the long run to make your roses healthier.

I would suggest to call your local rose society and ask one or the rosarians there what kind of soil is in your location and what is the best fertilizer/fungicide program for your area.

I last fertilized about 3 wks ago with milorganite, then foliage feed with fish fertilizer. Am trying that this year to see the difference. You people on this forum are the best, I have enjoyed each comment and learned alot. Thank you so much.