Help with my sick rose please?

[teachermom1]

Please help - I have a sick rose that I just don't know what to do with.

About 3 weeks ago I noticed the new growth was a pale green - light enough that I thought it was odd.

Soon, older leaves started showing some mottled yellowing. I have several new rose plants put in this year, and some of them are requiring almost daily watering in this terrible heat we have right now. So first I thought possibly an iron deficiency was going on and added some bone meal, but I also backed off on the watering. This rose didn't show as many signs of heat stress, so I thought maybe it was getting too much water.

I went on vacation and was gone about 5 days. I had a neighbor water twice while I was gone.

When I got back, the rose had dropped almost all its leaves. Only a few at the top remained.

The oddest thing is, when the symptoms first started, the plant had 5 or 6 buds on it. The buds developed and produced beautiful blooms, even as it dropped all the leaves.

I see no signs of black spot, rust, or powdery mildew. The leaves look perfectly fine, apart from turning light green and then yellow before falling off.

As the buds finished, I cut back the canes and I am seeing some new growth starting in a couple places. Any ideas?? I am stumped, and I really don't want to lose this new rose.

[luis_pr]

Heat stress can make the leaves yellow out and drop, especially older/inner leaves. An aphid infestation can also cause that problem. New leaves will develop in time but, if I were a plant in the summer, I think I would wait to do that when temperatures go down. Keep it well mulched and watered until then. Check the soil pH to see if it is too alkaline and to check soil nitrogen levels as well; nurseries sell soil testing kits for these two conditions. While the shrub is stressed, do not try to fertilize it anymore.

[teachermom1]

Thanks. I have been watering regularly - we haven't seen a drop of rain in weeks, and have had extremely hot temps. Most of my roses that are new this year are struggling, but nothing like this one.

I will check the soil and see if I come up with anything as well. Would aphids cause it to completely defoliate? Because it has very few leaves left.

[cynthia_h]

I've had aphids "enjoy" my roses, but never a complete defoliation.

Is it possible that [url=https://www.marinrose.org/virus.html]Rose Mosaic Virus[/url] has made a visit to your roses?

Cynthia H.
Sunset Zone 17, USDA Zone 9

[teachermom1]

Thanks for the link. I don't *think* that is the problem. The leaves don't really look like the pictures or descriptions. I really suspect a mineral deficiency or watering issue, but I could be wrong! Lol

[cynthia_h]

So first I thought possibly an iron deficiency was going on and added some bone meal, but I also backed off on the watering. This rose didn't show as many signs of heat stress, so I thought maybe it was getting too much water.

OK w/regard to the possible rose mosaic virus. *whew* But this part of your original post puzzles me. If you thought the rose was iron-deficient, why did you apply bone meal? Bone meal is usually considered to be a good source of calcium, but I've never heard that it's a good source of iron, too. I'm ready to be educated, though, if it has this additional virtue!

Usually when a plant drops its leaves, a survival mechanism has been brought into play. The plant is looking out for its sheer survival, so desperately that it has sacrificed its ability to perform photosynthesis.

Not sure what else to suggest at the moment....

Cynthia

[teachermom1]

Now, this I DO know the answer to! Bone meal helps the plant to take up iron that is in the soil but not available.

Iron deficiency due to high pH is sometimes a problem in soils with concrete walls or sidewalks nearby, because of the limestone in those materials leeching into the soil.

And, this rose just happens to be located next to a sidewalk. When I think about it, bone meal is pretty slow acting, so it is possible that this is indeed the problem, but it is taking a while for the plant to get the iron it needs and recover. Your question may have just made my brain actually process what I already knew but wasn't putting together, so thank you!! I am feeling pretty sure now that it is an iron deficiency and I was on the right track, but too impatient in my treatment.

[teachermom1]

Rereading your post, I want to clarify that bone meal only helps iron deficiency if it is caused by a high soil pH. It does not add iron, the iron has to already be there or be added in another manner if it is lacking. Just want to be sure readers will pick up on that important tidbit.

I totally agree on the survival mechanism, which is why I am so worried. Now that my head is getting this sorted, I think I need to decide how to lower that pH as fast as possible. So, if anyone has thoughts on that, please share!!

[luis_pr]

I would confirm that the soil pH is off by using a soil pH kit. The cheap ones are not that exact but it sounds that you just need to know if it is very alkaline (high soil pH) or very acidic (low soil pH). Based on that, take appropriate action: (a) add garden lime if it is too acidic; (b) add garden sulphur; iron sulfate, green sand or iron-chelated acidifying liquid compounds if it is too alkaline. If the soil pH is close to neutral, no action is needed (that is, soil pH is not a problem in your garden).

[teachermom1]

I will do some soil testing, thanks for the input on fixing pH!

[teachermom1]

The pH came up slightly alkaline. Not a lot, just a touch. Would that be enough to cause an iron deficiency?

I also did some digging to check out the soil moisture. The soil was quite dry, although not rock hard. We have enough clay that extreme dryness will make it rock hard. Gave it a long drink today and will increase watering, took a soil sample to check NPK and am waiting for it to fully settle, but I don't expect any issues there. Here in IL the soil obviously tends to be quite rich, and this spot has rested for several years. The roots I saw were white & healthy looking.

I'm wondering if I have multiple things going on here. Those new leaves were very noticeable in their light color, but perhaps the older leaves dropped from a lack of water.

[teachermom1]

Interestingly, soil tested as having a nitrogen deficiency. Which is really surprising with our rich soil and in a spot that has rested for several years. These symptoms don't seem like N deficiency, with new growth affected first. And the plant seemed to be doing just fine until these symptoms started. Hmm.

[luis_pr]

Yes, very interesting. But nitrogen deficiency is not obvious at first. When it gets bad then you start to see symptoms in the plants. And these may not be obvious since not all plants will trigger symptoms at the same deficiency levels.

You may want to send a soil sample to your Agriculture Extension Service for proper analysis now since there could be more mineral deficiencies. You can include comments listings the types of plants that you are growing so they can come back with results and a recovery plan suitable to your garden. In the mean time, add a little of acidifying liquid compounds, keep the rose well mulched and supply moisture but do not water too much. A gallon per watering on a 1-2 feet rose is fine. Do not water again if the soil already feels moist or wet.

In the meantime, when you fertilize, use slow-release general-purpose fertilizers like Osmocote 10-10-10 or organic ones (compost, composted manure, cottonseed meal, etc.). Blood meal is a good choice too for nitrogen deficient areas as it has an average NPK Nitrogen Ratio of 12 or 13, almost no phosphorus and a small amount of pottasium. Cottonseed meal is good too; it has less nitrogen and slightly more of the other two.

[dbang10]

Your first description made me think iron deficiency but when you mentioned the leaves are all falling off, that is definitely not an iron problem. If you had the most extreme iron problem your foliage would go white but still feel soft to the touch. Sometimes over watering can create an over saturation of the soil and the roots no long have oxygen. I have found that watering once or twice a week with a deep soak is much better than watering every day.

[PreserveFlowers]

I had this issue last year with ridiculously high temps and no rain. Almost everything that got direct sunlight died. We tried something at the end of the summer and had a little bit of luck. We used coffee grounds from starbucks mixed with the soil and kept them pretty damp with watering. This seemed to keep some moisture in without getting too humid.