Hi I have mini rose in a container that leafed out really nice in the spring but then the leaves start showing grey spots and holes. I got some neem oil spray and the leaves pretty much all fell off after the first batch of flowers. Then it releafed great and I thought fine. But then it started getting the grey spots again along with yellow/black spots with no holes. All the leaves died off and then it releafed again. This is the third cycle this season. Can anyone help me identify how I should be treating these issues? I think there might be two different issues.
Yes, you have 2 different problems. First, the small holes that look like windows are caused by rose sawfly, sometimes called rose slugs. They look like caterpillars, but they are not, so using BT, will not control them. Neem oil may help, but you would have to spray under the leaves and coat these insects for any control. Second, As charming as miniature roses are, they are generally not very disease resistant, especially in more hot and humid climates. Your rose leaves are probably being defoliated by the fungal disease call black spot. If you are strictly organic gardener, it will be more of a challenge controlling this common leaf spot disease. However, you can try the following and see if any of these recommendations help: dissolve 2 Tablespoons of Epsom salts in one gallon of water, spray weekly without fail; you can rotate with a copper fungicide infrequently (every few months) and another week use something like Arber, which is Bacillus amyloliquefaciens strain F727. Black spot needs free moisture to grow and spread. If you can keep your rose leaves dry you will see less of this disease. Anything you decide to spray must be done weekly if you have any hope of keeping healthy rose leaves.
For rose saw fly we can recommend several systemic insecticides to spray your rose leaves, if you are willing to do so.
Let us know if you are willing to spray a commercial fungicide to protect your rose leaves and we can give you several recommendations.