Question
Hi Melissa, I bought a dozen or so rose bushes last season. All grew fine but just about all of them were affected by black spot to some degree by the end of the season. I would dig them out and replace them with more resistant varieties, but I wont because a)it would start getting prohibitively expensive! and b)I believe the black spot is being carried in the air from neighbours garden! and finally c) they were supposed to be resistant anyhow (I guess 'resistant' and 'immune' are slightly different!)

So, having accepted that I'm likely to have black spot this year my problem is I don't wish to use sprays from now - the bees have started buzzing around.  What is the best way to treat roses against black spot without chemicals...is there any way to effectively pre treat, or will i have to resort to firefighting against an unstoppable enemy by removing affected leaves? (I have new growth now after pruning, with fresh unblighted leaves appearing).

Secondly, and very much for the same reasons as the blackspot, i have no inclination to use chemicals against the ever present aphid population, with the aim of doing as much as i can in protecting our dwindling honey bee population. Bees aren't particularly interested in my roses, though i have noticed a few having a look see! Is there a non chemical method of halting my unwelcome green friends!

Hope that makes sense

Thanks in anticipation of your answers

Mark (South coast of UK)

Answer
Dear Mark, I absolutely share your concerns about spraying, and I applaud you for your concern about the bees.  I actually have a solution to your problem that will not affect the bees.  First, the most important way to avoid injury to the bees is to spray on cloudy days or in areas where flowers are not blooming.  If no bees are present, then they won't be harmed.  Second, if you spray with an organic, you will also avoid injury to the bees.  I am suggesting that gardeners use NEEM to control most of their garden problems.  Neem is an organic compound made from the seeds of the NEEM tree and it is effective against fungus, insects, and mites.  So if you spray on a cloudy day, you will not be bothering the bees at all and it will get rid of your blackspot and any aphids or thrips that come by to feast on your roses.  Regular applications of Neem Oil, a botanical insecticide, can help control and prevent black spot. For prevention, apply on a 14 day schedule, if black spot is already present spray every 7 days. You can also apply environmental controls. Prune and remove all the affected parts on the rose bush. Also rake up any leaves that may have already fallen to the ground. Never compost the affected parts as spores may survive in the soil and spread to other plants. In order to prevent overwintering of the spores thoroughly remove all diseased leaves in the fall and cut canes a couple of inches into the healthy wood. Also,when watering your roses, always water from the base of the plant and never from the top. It is also best to water your roses in the morning to allow the leaves the most time to dry.  There are also natural controls. In order to prevent germination of the black spot spores, apply either sulfur dust or wettable sulfur to the plant. Sulfur can be applied every 5-10 days but thourough coverage of the plant is critical. Applying sulfur does not kill the fungi already on the plant.  Another option is to spray the roses with a mixture of baking soda and water (two tablespoons per gallon), however, roses will have to be sprayed weekly and after every heavy rain.  In general, grandiflora and floribunda varieties are more resistant to black spot than hybrid teas. Most black spot resistant roses will still occasionally get infected with the fungus but infections tend to be on a much smaller scale. Resistant hybrid teas include the Chrysler Imperial and the Tropicana.  Keeping your roses healthy and free from aphids and thrips will also help with the blackspot.  I hope this information helps, but please feel free to write back if you need more information.  You will probably not need to use all these controls, but a judicious use of some of them can greatly help your roses.  Good luck, Melissa