how to keep the yellow leaves with black spots from coming on my roese?

Question

ive tried the 3and 1 product someone told me to use amonia and dish detergent deluted in water but will that harm the plant

Answer 1

Black spot is caused by a fungus, Diplocarpon rosae. Some roses are more susceptible than others. The spores that spread the fungus are carried by water as it is splashed onto other areas or other plants.
It's important to clean up fallen leaves & allow good air circulation around plants.

Jerry Baker (Master Gardener) advises using a fungicide to knock out the fungus, & then using a homemade control for Black spot: Spray them with a mixture of 1 tbsp. of baking soda, 1 tbsp. of light vegetable oil, and 1 tbsp. of soap in 1 gallon of water. http://www.jerrybaker.com/index.asp?PageAction=Custom&ID=2
Some alternate baking soda spray with a vinegar spray:1tablsp Apple cider vinegar, 1teasp Ivory soap, 1teasp canola oil in 32oz spray bottle
Other Methods of control:
Sulfur powder is a preventative, it will not kill the fungus spores, but it will prevent a new generation from germinating.

Dormant oil or Bordeaux mixture when plants are dormant (usually in winter).

Mix a handful of cornmeal in the soil around your rose bushes to control black spot. Cornmeal controls diseases by providing and stimulating existing beneficial microorganisms that feed on pathogens.

Water early in the day so the leaves dry quickly, or water just the base of the rose bush so the leaves won't get wet & the fungus will not get the opportunity to spread & thrive. The fungus is most serious in regions of high rainfall and high humidity because "the infection takes place only when water remains on the leaves for seven or more hours". http://www.ext.vt.edu/pubs/plantdiseasefs/450-617/450-617.html
Good luck with your rose bush! Hope this helps.

Answer 2

Hi,
Yes , the products mentioned will harm the plant and the earthworms around the roots.

Remove the damaged leaves and take them away from the plant in a plastic bag. Try to increase the air circulation around the plant. This means, do not crowd other plants around your rose.

Ask at a full service garden center for purchase of roses that are the least likely to get the "black-spot".

Bye ,

RP

Answer 3

You've got a black fungus infestation. You can get anti-fungal sprays at any home improvement store or garden center.

You might also consider removing any dead leaves from around the rose bushes and replace whatever mulch you had around them. And, try to avoid getting the foliage wet when you water and water in the monring, so any water that does get on the foliage will dry off during the day.

Answer 4

Get a box of corn meal and spread about half the box around the base of the plant. Repeat in 6 weeks. Works very good.

Answer 5

I wouldn't put anything toxic on my roses. I'm not sure what works but I know it's called black spot, you could search on net for natural remedies. I do know you have to keep them picked off and trown away from all your other plants because it can spread. Also, you might want to change your oil because it caught the disease somehow. Jennifer