I have a raised rose bed that has organic soil, organic compost and organic mulch. I have used only organic rose fertilizers. Early this spring I started applying agricultural cornmeal under the rose bushes and have continued using it. I sprayed with baking soda. I have removed leaves with black spot and have watered the proper amount at the proper times and not watered too much or too little. Even with all of this careful attention my roses have lots of black spot and now also have powdery mildew. And supposedly the roses I have are disease resistant. I am very distraught because I love roses. Any suggestions please? Thank you.
You have done most everything right. The soil might need to be supplemented a bit. Roses are heavy feeders. Get some organic fertilizer on them right away and start foliar feeding them every week, early in the morning before it gets hot. Make sure you sprinkler system isn't hitting the leaves. If it is you might have to shut those heads down and hand water. You said you LOVE them.
You also should make sure that there's enough air circulation around your roses. I have several antique roses that are totally neglected and they look great and still bloom. I think you've done things right, just make sure they're bot too close together or up againsta a wall. Also, when you water, make sure you only water at the base and not the leaves.
You have to spray regularly...once a week is best. Use either baking soda in water or vinegar in water...but not both at the same time. That way you put the Ph range outside the range the mildew or black spot can live. i have found the mildew to be more sensitive to vinegar than baking soda but baking soda seems easier cause i always have that.
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