My rose bushes are just beginning to leaf out and I already have black spot showing up. I have had this problem every year for the past 4-5 years, but this is the first time it has shown up so early. Do you or anyone have any kind of preventive schedule to keep this from becoming a problem. If I had a maintenance schedule that someone else has used successfully, one that I could follow, maybe my roses won't start losing all their leaves and I will have beautiful blooms this year. I live in Cleveland, Ohio and and we are experiencing 70 degree weather in March, which is very unusual. Everything is leafing out early.
As you have discovered, Black spot (Diplocarpon Rosea) is a common problem no matter who you are if you grow Roses, there are some new Roses bread for being Black Spot resistant BUT, several that my friends have tried still have this problem, perhaps not as bad, but they find there is NO Rose completely free from this pest.
The black spot is able to overwinter in the soil that is spread from the fallen leaves that bare this pest. so being fatigues with the hygiene of the Roses as this pest first shows up will help. to do this you must gather ALL the fallen leaves as they drop (I don't mean stand beside the Roses and catch leaves) I mean every few days as you walk around the garden, pick up any leaves dropped on the soil. The next thing you need to do is BURN the affected leaves, this is the only way to prevent more infestation. Another thing taught to me was for wall climber Roses, have a space of 5-6 inches between wall and frame to allow air to circulate between front and back of foliage or you will get even more diseases like gray mold, black spot and more bugs due to heat from wall in summer and shelter in winter, I use wooden battens and empty cotton reals for spacers, it works and allows you to remove the frame for cleaning and painting IF you add hinges to bottom.
I would at this stage pick off any leaves you see carrying this spot as the disease will be passed on from leaf to leaf by insects etc, it takes a while for a whole bush/ climber etc to be totally infected so picking the leaves of now gives time for the new leaves to regrow.
I know of no Roses that have died from this disease and it never appears to have any effect on flowering but it is unsightly and I would say for the next several years you will have to follow a rigorous regime to try rid the plants of this.
there are sprays you can buy from the garden center but perhaps IF there is a Rose forum on Dave's, you could try asking the more expert among them. I only grow mine for pleasure OR as my husband would say, to feed the deer who meander in through our garden as we are encircled by woods and the ocean which is a favorite area for all dear, seaweed for supper and lush garden plants for desert, ha, ha, ha. better cared for than DH.
I have used the spray only one year and was advised to spray the soil also, but my late Dad had a laugh at all that, and I went back to his tried and tested method which is the same as I have given you. Hope it helps Sue as this disease spoils the look of the roses. Remember you wont get rid of this in one season, you need to work at it over 2-3 seasons and stick to the striked regime of gathering the leaves and BURNING them or the disease will lay dormant till the soil warms up again.
Good luck hope this helps and you get some form of results.
best wishes. WeeNel.
WeeNel again, have just chatted to friend who grows lots of Roses and he has suggested the latest way for Black spot as well as what I do but also Spray with Systhane OR Supercrab and you do this in spring JUST as the leaf buds are opening, he recommends you treat the whole plant, branches, leaf, flowers and soil as well. Repeat 1 week later then again in summer. He's not sure IF you can get these sprays in USA as all countries have different regulations on what armatures can buy for gardening problems.
He also recommended making sure you add potash as a shortage of this in your growing medium allows this deficiency to get hold. so theres another few hint's and tips for you to try out.
Good luck, WeeNel.
Thank you so much for your replies WeNell and themoonhowl. I just hate it when fall arrives and the black spot has decimated almost all the leaves on my roses. In Cleveland, Ohio this year, we have had an early spring (3-70 degree days), then got bounced back to freezing temps. It is getting a little frustrating. Mother Nature sure has a sense of humor! I will try to both, pick those diseased leaves off and use the Bayer Advanced. This year I WILL get a second season out of my roses!!!!! My beloved Dolly Parton rose will be HUGE and I WILL get more than three blooms!!!!! LOL Thanks again! Sue
I echo themoonhowl and say welcome also, just make sure all the leaves that fall to the ground are collected and also don't expect the Roses to be Black Spot free completely this year, you do have to work at it but remember the Roses wont be killed by this so have great pleasure form all the blooms, these plants have to work hard trying to grow, bloooooooom and fend off all the things nature throws at them. enjoy the season and good luck.