Black and Yellow leaves - Please Help

[mukesh_thiru]

I got a rose plant around a month back and it had been doing very well. It is planted in a 12 inch pot with miraclegro potting mix. I have been watering the plant daily either in the morning or in the evening.
I live in Peoria, Arizona, US. Recently the leaves started turning black, then yellow and started withering. Not sure if it is due to over- watering or salt content or heat. Somebody please advise.

[luis_pr]

The fungal disease Black Spot will cause leaves to develop black spots and then the affected leaves will turn yellow and fall. Are you familiar with black spot? Could this be the cause? A picture might help tell for sure.

[mukesh_thiru]

I took all the leaves which has fallen off the plants, bought fertilizer and pesticide. The leaves are drying. I water it once in two days. I don't spray water to the leaves.
As I mentioned I live in Arizona and the temp here is around 110F

See pictures

[url=https://img837.imageshack.us/I/imag0036.jpg/][img]https://img837.imageshack.us/img837/972/imag0036.th.jpg[/img][/url]
[url=https://img833.imageshack.us/I/imag0035.jpg/][img]https://img833.imageshack.us/img833/3826/imag0035.th.jpg[/img][/url]
[url=https://img837.imageshack.us/I/imag0033.jpg/][img]https://img837.imageshack.us/img837/7629/imag0033.th.jpg[/img][/url]
[url=https://img837.imageshack.us/I/imag0032.jpg/][img]https://img837.imageshack.us/img837/6353/imag0032.th.jpg[/img][/url]

[The Helpful Gardener]

Luis was correct, you have black spot.

It is a fungal disease. Try copper sulphate as a cure...

HG

[mukesh_thiru]

Can I use Neem Oil for fungal Disease?

Luis was correct, you have black spot.

It is a fungal disease. Try copper sulphate as a cure...

HG

[cynthia_h]

Neem is recommended for insect control. I'm not familiar with it in treating plant diseases. There are several recommendations on this forum for either a solution of milk, diluted with water, *or* a solution of baking soda, diluted with water, to combat fungal diseases.

Cynthia H.
Sunset Zone 17, USDA Zone 9

[The Helpful Gardener]

As it is an oil, it can be a decent anti-fungal, although the "cure" is mechanical (oil smothering the fungus and fruiting bodies) rather than chemical. But when I am on neem patrol for bugs, I often spray the powdery mildew, and it does knock it back pretty well...

But I will use copper sulphate on occasion to really get rid of it, and milk sprays as a preventitive once a week.

HG

[luis_pr]

I could not identify for sure if you were mulching. Mulching the rose might also help you, mukesh_thiru.

One question. What material is the pot made of? Seems metallic looking? If it is, I would not let it get too much direct sunlight as it may dry out the potting soil in contact with the metal quite fast.

[professorroush]

Hate to disagree, but I don't think that's blackspot. Most of that damage, especially on the leaf edges, is caused by too much dryness; or letting the soil get too dry between waterings. I didn't see any leaves with the characteristic black spot lesion (look on the internet for pictures).

[The Helpful Gardener]

The Prof has a point; you usually see more yellowing than just browning in the leaf with black spot (although the black lesions are not a necessity despite the name). I made a knee jerk call on that one, and the Prof seems to be a pretty good second opinion...

HG

[professorroush]

I'm not a rose expert, but I did stay at a Holiday Inn Express Saturday night.

...And I grow about 150 roses in one of the most hot, humid, inhospitable environments in the US.