deltarose
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Joined: Thu Jul 24, 2014 3:15 pm
Location: Mississippi - 70 miles south of Memphis, TN - 10 miles from Miss River

Unknown Disease on Hybrid Tea Rose

Thursday, July 24th

Hi. I am Merlyn and I live in the Mississippi Delta about 70 miles south of Memphis, TN. It is pretty humid here and the temperature has been in the lower 90's recently. We have had a lot of rain this year. I have a sick Tea rose (John Kennedy). I first noticed a the leaves browning on Tuesday. It significantly worse today. I am wondering if I need to remove it to prevent the spread of whatever it is to the other roses. It seems to start at the tip of the leaf and move toward the stem. My spray routine is pentathlon every 7 to 10 days. Add Banner Max every other week. I also add Malathion or orthene (acephate) as needed for insects). Please advise. Thanks ! - Merlyn
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Lindsaylew82
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Location: Upstate, SC

I'm not familiar with the sprays that you speak of, but I have roses, and I've noticed a. Few things going on that I am familiar with.

The leaves that look like they are getting ready to go dark are chlorosed. Is one of those sprays a plant food? Severe chlorides can cause die off like that. Some of your leaves are showing signs of severe chlorosis. Chlorosis is nutritional. Either they have no nutrients, or the ph is at level that it is making the nutrients unavailable to the plant. High or low ph soils can "lock up" nutrients. Nutritionally stressed plants are more susceptible to disease.

It looks like it could be fungal. Is one of your sprays for fungus? I'd definitely remove any foliage that looks diseased. That will help prevent spread to your other plants.

deltarose
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Joined: Thu Jul 24, 2014 3:15 pm
Location: Mississippi - 70 miles south of Memphis, TN - 10 miles from Miss River

Thanks for the suggestions. I'll check the pH on my soil to make sure it is right. The sprays that I use include an insecticide, a fungicide and a foliar feed. I also sent the photo to our local county agent and one of his contacts suggested that it might be rose mosaic virus. Thanks again - Merlyn

luis_pr
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Location: Hurst, TX USA Zone 7b/8a

The leaves are not too clear. But some times, RMV can show up as leaves whose leaf veins turn white (more common) or yellow (less so) like this example of white veins:

https://www.love-of-roses.com/rose-mosaic.html

Because yellow leaf veins can also be a sign of RMV, I try to confirm RMV by looking at other leaves with white/yellow splotches. If you cannot confirm it that way, I then treat it like a soil pH problem caused by high alkaline levels or too much sudden water. Do note that soil pH problems would display leaf veins that are yellow, not white.

If it is a soil pH issue, it should improve in 2-3 weeks. If the problem does not improve, you can then take a sample in a sealed envelope to your local county agent or a nearby plant nursery for confirmation.

deltarose
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Joined: Thu Jul 24, 2014 3:15 pm
Location: Mississippi - 70 miles south of Memphis, TN - 10 miles from Miss River

Thank you for your advice. I removed all the infected leaves and cut away dead looking canes. It is looking about the same. It hasn't put out any new leaves. The part of the plant that seemed unaffected is blooming. The veins were more yellow than white. All I did to treat it was to remove affected plant matter and spray again with the fungicide I normally use (another name for manzate) and bannermax. I have not seen any evidence of trouble in neighboring roses. Thanks again or your time.

Merlyn

imafan26
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Location: Hawaii, zone 12a 587 ft elev.

Are you sure all of those sprays are compatible?

I used to use Bayer tree and shrub, it contains merit. It protects for one year for most pests and diseases including blackspot, powdery mildew, japanese beetles, and borers. It is however very toxic to bees and I did not have a year round problem. I plant the roses near a streetlight and I have four o'clocks so I pretty much do not have a beetle problem in my front yard. I only have one tea rose in the back yard that does get leaves eaten by beetles but the other roses aren't bothered.

I have swtiched to only using systemic rose care only when it rains a lot and I can't keep up with the regular fungicide program. It works for six weeks and controls blackspot which is my biggest problem. I have also selected roses with glossy green leaves that helps with mildew. If I do it in time I can use horticultural oil as a preventive for mildew in wet weather and my roses are watered by drip. I feed the roses after each bloom cycle and I have planted back companion plants to bring back the beneficial insects to take care of the rest of the bugs.

I also get rid of roses that are just not very disease resistant. I did have John F. Kennedy, and I had a lot of problems with it so I replaced it with a rose that is much hardier. It is also a small rose and a short shrub. Since I underplant my roses, I prefer taller roses. I don't have a pure white rose, I did have iceberg which is a very disease resistant grandiflora, but I did not like the weak necks and droopy blooms. I have instead more roses that have better bud form and large blooms like pristine (pink edge), pascali, white Meidiland, and honor. Iceberg is a very good bloomer and disease resistant, I just did not like it. Pascali and Honor are the smallest of the whites I have grown with blooms about 3 inches.



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