Rose bush help! Sudden decline... fungal rust? pest? nutrition?

New to rose growing. Bought a house 3 yrs ago with mature rose bush about 24 yrs old. Was fine this spring with lots of blooms. But suddenly 2 weeks ago after severely wet weather, we started to see major die back.

  • Instead of ripening, hips are rotting from the top down, turning to “mummies” and the stem dying back to the main branch.
  • Leaves yellowing with dark spots that turn to holes.
  • White caked coating on base of plant at ground level.
  • Checked backs of leaves and found no live pests (only two small pest-looking things but that was it on the entire plant.)

Don’t want to lose this mature plant as it’s lovely and has been blooming the last 3 yrs with no issues.

One other point: it’s planted on the same arbor as a grape vine that’s suffering from black rot fungus because of the severely wet weather… makes me suspicious that the issue with the rose is also fungal.

If it’s fungal what’ the right treatment… neem oil? copper-based fungicide?

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Welcome! You don’t indicate where you are, but I’ll guess the nyc may indicate around New York City?

I don’t see anything particularly severe from your photo. The foliage on the right side show the characteristic “window” damage of sawfly larvae, “Rose Slugs” which are small green worms that eat the under sides of the leaves, leaving the cuticle or “skin” of the leaf. If you hold that leaf up to the light, you’ll notice those “holes” appear like small windows covered in wax paper appearing “glass”. The rose slugs LOVE green house conditions…warm, moist, protected, like being in a green house. If the weather dries out; temps get too cold or too hot, they migrate elsewhere. If it remains those mild, humid temps, they will hang around for many generations until winter puts an end to their season. It’s quite possible you’re seeing damage they caused while they were still active. They may not be active now, or you may have not seen them as newly hatched larvae are very tiny and “leaf colored”. If you’re concerned and wish to treat for them, obtain Lady Bugs as they will eat them. If you have used systemic insecticides or intend to use any insecticides, forget the Lady Bugs. Predators are more susceptible to poisons than pests are. Why waste the money and the poor predators?

The rotting hip is perfectly normal after a severe wet period. It’s natural. Flowering is ovulation. Hips are pregnancy. The hip contains seeds. Everything in Nature is programmed to replicate itself before it dies. For those seeds to accomplish their natural “jobs”, something has to eat that hip and ‘spread’ the seed; harvest and plant the seeds; or the hip has to rot, fall off and the seeds germinate where they fall. So, it’s been severely wet where the plant grows. Sap pressure is greatest at the tips of the canes so that hip is full of moisture. There are fungi and mold spores everywhere. True to Nature, the hip is rotting so the seeds can be dispersed. Nothing to worry about. You should remove the rotting hip and the discolored, dying stem beneath it. Cane pieces will die unless there is a viable growth bud at their top ends. If something damages the top bud and the two guard eyes with them, there can be no growth from them so that piece of cane dies back to a point where the cane can grow. If there is a canker or other disease causing the dieback, that can spread farther down the cane than it would normally, so it’s safest to prune off that dying portion to prevent the potential of it spreading farther down the cane.

The white caked coating on the base of the plant sounds like a salt layer. Is this by chance a potted rose? If so, does the pot drain out on a surface or is it in a saucer? Unless it’s distilled, water contains minerals and “salts”. Inorganic fertilizers are ‘salts’ of the nutrients as that is the only form of them the plant is able to absorb. Organics have to be digested into the salt forms of their nutrients by fungi and bacteria for the plants to absorb. If the drainage isn’t sufficient, those ‘salts’ will concentrate and be drawn back to the soil surface as the water is drawn up through evaporation. As it evaporates, it leaves the salts behind in an often white coating.

If it’s in the ground, then perhaps the soil where the plant is isn’t deep so the drainage isn’t great. Salts are being brought to the surface through evaporation. Or, if you’ve applied a pelletized fertilizer, perhaps all that rain has dissolved it quickly and those salts are being drawn up through evaporation?

As long as the main canes are normal colored and not shriveled (still turgid, full of water), the plant is likely in good condition and not in danger. Foliage can be adversely affected by periods of excess water and humidity and the plant still be fine in the long run.

Grapes experience different fungal disease and don’t usually share the same pathogens. Is the “black rot fungus” on the grape on the leaf surfaces? Will the black wipe off with your fingers? I don’t know if you’re familiar with the “disease” Black Sooty Mold, but when there are sucking insects on the under sides of leaves, such as mites, aphids, mealy bugs and others, they suck the sap from the plant tissue, then they release sugar water, “honey dew”, which lands on the surfaces of the leaves beneath them. There is literally a fungus which grows in and feeds on the sugar water called “Black Sooty Mold”. If it’s new enough and hasn’t been there long enough to dry on the leaf surfaces, it can be washed off with a hose. If it’s too dried on, you may have to literally wash the leaves with a wash cloth and running water then rinse. Or you can remove the leaves but then you may encounter sun damage to the grape stems.

I know you’ve just had an extremely wet period, but the most “organic”, least toxic method of getting rid of all the sucking insects on the leaf undersides is to wash them off with a water wand.


You can find them in many big box stores, nurseries, garden centers or on line. Make sure the one you obtain has the water turn off on it so you can prevent waste and wetting yourself with it.

It may take several uses to knock down any infestation of the insects and wash off heavy concentrations of sooty mold, but keep at it. Using it on the rose can also have benefit in removing any of the saw fly larvae still hanging around. Because you possibly live in a high disease pressure area, I’d use the water wand earlier in the day so the foliage has a chance to dry off as the day heats up. If you’ve not had disease issues before, continue your other routines with the rose and grape. Unless you’re using anything systemic on the rose. Any systemic insecticide or fungicide you put in the soil for the rose may potentially be absorbed by grape roots and could possibly cause you and your family to be eating those chemicals in the grapes.

I hope some of this helps you figure out what’s going on with your plants. That’s about all I can come up with from the one photo and your description. Good luck!

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Thank you so much for the advice. As a newbie, the posting system here only let me upload one photo. But I will add another here in case it helps.

(The grape vine is infected with “black rot” fungus (Guignardia bidwelli) which is common around here in upstate NY. It causes brown spots on the leaves and causes the fruit to dry out and shrivel into what are called “mummies.” I didn’t get to spraying early enough so it will be a battle all summer now.)

The rose issue was concerning because last year the hips ripened into beautiful, plump red fruits… but this year they are just turning brown/black and shriveling.

My other concern is the yellowing leaves. I did know that the leaves on the upper right have that classic “windowpane” pattern of “rose slugs.” It’s the yellowing leaves that are spreading very quickly across the entire plant. About 1/3 of the leaves are yellowed and sickly looking.

Photo below.

Thanks again for your help.

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One other question… I have been spraying the grape vine with a combination of organic fungicides… rotating three different ones to prevent the fungus from developing resistance. I’ve been using neem oil, a copper-based fungicide, and a clove-oil based fungicide…

Since the rose and grapevine are growing on the same arbor… I’m not sure of any of the over-spray from the grape vine treatment might be affecting the rose bush.

All three fungicides say they are safe for roses on the label … but as a novice I’m not sure…

and you can see the extent of the yellowing and leaf drop in this photo.

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Thanks for the further illustration and explanation. I’ll let you deal with the grape as I’m not as well versed in their culture and definitely not in their care where there are significantly greater disease issues.

Yellowing of the rose foliage after excessive rains is normal. You likely have spotting fungi, whether it’s black spot or cercospora I’m not sure, but there are many others here who can more easily diagnose that issue for you. Thankfully, those aren’t issues here in the arid, hot West.

What you’re using on the grape would only be damaging to the rose in periods of higher heat, more intense direct sun and/or significant aridity. Copper can burn rose foliage in all of those conditions. The others are oils, which are decent treatments in many cases. They can be damaging to rose foliage because they seal the pertioles, the pores on the foliage under sides, preventing them from releasing water when the foliage is in direct, hot sun. That’s what creates sap pressure, pushes growth, and assists the plant in cooling itself in hot sun. When the petioles are sealed with oil, the sun causes the water in the plant to expand and not be able to be released, so the tissues literally cook, similarly to how they cook in a microwave. It kills the foilage and new, soft growth causing them to yellow and fall off.

Some yellowing is normal, as you’re likely aware. If the leaf isn’t receiving the threshold of light it requires to generate more chlorophyll than it requires to function, the plant absorbs the chlorophyll from it causing it to yellow and fall off. As the plant grows, new growth covers and blocks light from the leaves beneath it and in the inside of the plant so that foliage yellowing is normal and nothing to worry about. When the new leaves and those on the outside surfaces of the plant begin yellowing, you have cause for worry. The black spot and cercospora fungi are likely enjoying the warm, moist conditions they require to germinate. Hopefully that pressure will lessen as conditions warm and the humidity and moisture dry out more.

You could, if you desire, hand pick the affected leaves and rake up any which have fallen to the ground, then see if there is further spread. If your temperatures aren’t exceeding those listed on the labels of the products you have, and if they are listed as effective against black spot and cercospora, treating the rose with them should help prevent further issues. If you expect temps to rise to the range the labels warn against their use in the next month or so, I’d not use any oils as they don’t wash off and can still burn in hot conditions four and often a few more weeks after application. At least they do out West. Your mileage may vary.

I still don’t think your rose is in danger of being lost. Leaf drop after excessive rain is normal. If the soil is water logged, the plant can be struggling to rid itself of too much water and the roots struggling for oxygen. Those issues will subside if the soil drains quickly enough. That much water with sun and warmth will push tremendous growth and that growth relies upon resources re absorbed from older foliage to push its development.

You can diagnose rust easily by looking for the “rusty” pustules on the foliage under sides. Rose rust fungus on leaves - Stock Image - B275/0042 - Science Photo Library and on the surfaces. How to Identify and Treat Rose Rust | Gardener’s Path

Last year the hips ripened because they weren’t drowned in too much water. This year, they are. They’re fruit and just like apples and berries, too much water while they are ripening causes them to over fill and rot.

I’m not sure whether you were limited to uploading one photo because you are new to the forum or if it was due to your file size. Perhaps the safeguards built into the forum will allow you to post multiple photos with use? I’ll be interested to see if that’s the case. I’d just keep an eye on your rose. Take whatever steps you deem desirable and necessary given your upcoming weather forecasts, time and energy. I’m glad you’re being proactive. Too often help is requested once the affected plant is mummified.

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Thank you! Very very helpful. :grinning_face:

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You’re welcome. I hope it helps!

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