Leaf pattern and nutritional deficiency?

9 years ago

The lower (older) leaves of a hybrid perpetual are showing a vivid pattern that I suspect is caused by nutritional deficiency. I do water this bed regularly, so while there may be mild water stress when it gets hot, on the whole I think it gets reasonable water. And I remember that this same thing has happened on previous years.

My soil is a sandy clay and it is alkaline. There is a lot of limestone around here. ( In fact there are several wineries on the next hill over; the Santa Cruz Mountain appellation is the oldest wine making region in California.) I do understand that high pH can interfere with plants being able to make use of nutrition that is actually present in the soil. Still, I am curious to know that it actually is that the plant is lacking.

I should mention that my best guess is magnesium. I originally thought iron deficiency, but this is happening on older leaves. I do have other roses where it is happening to younger leaves and there I suspect iron deficiency.

I've studied pictures in books and come up with a different decision each time. I'd like some other opinions.

Rosefolly

This post was edited by rosefolly on Sun, Jul 20, 14 at 10:05

Comments (8)

roseseek
9 years ago
Whatever it is, I'm seeing it all around in my travels here. It could be heat related as well as geriatric foliage, deficiencies or toxicities of some kind. As long as the plant keeps growing and pushing blooms, I don't worry about it. IF rains ever come, most things will sort themselves out...I pray. Kim
jerijen
9 years ago
And if rain does NOT come, we'll have a lot more to worry about than some leaf discoloration near the bottoms of plants.
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malcolm_manners
9 years ago
These symptoms are not typical of any nutritional deficiency. I suspect it is weather-related.
nikthegreek
9 years ago
I agree that this does not have the typical look of a nutrient deficiency and it probably isn't. Talking of deficiencies I should point out that gardeners are often quick to attribute chlorotic looking leaves to iron, manganese or magnesium deficiencies while ignoring the most common cause of chlorosis in gardens which is nitrogen deficiency. Magnesium deficiency in roses btw is not very common in neutral to alkaline soils as far as I understand.
Nik
roseseek
9 years ago
I've always read that iron becomes unavailable in alkalinity by being "locked up" in insoluble compounds. The fastest, easiest, cheapest way to "acidify" is to add nitrogen. Citrus and Azalea/Camellia food are high nitrogen. By "acidifying" the alkalinity, you would then release the iron, wouldn't you? You can also accomplish similiar results by adding soil sulfur or aluminum phosphate such as Hydranea Blue. So, by increasing the nitrogen, you should also be making any existing iron available. Kim
nikthegreek
9 years ago
Kim, I'm not sure it's that simple. Most ways of providing nitrogen produce an acid reaction and have a temporary acidifying effect but not all. For example ammonium sulphate produces acidifying ÃÂÃÂ4+ cations and is the most acidifying nitrogen fertiliser but calcium nitrate increases soil alkalinity and is often a good way of providing nitrogen in acid soils while calcium ammonium nitrate (CAN or nitrolimestone) does not significantly affect soil pH.
Nik

This post was edited by nikthegreek on Mon, Jul 21, 14 at 3:53
michaelg
9 years ago
As Malcom said, this doesn't look like a deficiency.
rosefolly
Original Author
9 years ago
Thanks for the comments. In any case, there is not much I can do about it. Mostly I was curious.

Rosefolly