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What’s wrong with my rose? Oddball rose buds could be signs of stress

Combination of too much heat or not enough water can trigger phyllody

Sacramento Digs Gardening
BY Debbie Arrington PUBLISHED JUN 8, 2022

These are the weird rose buds that

prompted Kristine Castrillo's letter. The

condition is called phyllody. (Photo courtesy

Kristine Castrillo)

What’s wrong with my rose? If buds look like they grew in “The Little Shop of Horrors,” hormones could be the problem. But why?

A question from Kristine Castrillo of Vallejo, a regular listener to our friend Farmer Fred Hoffman’s podcast, prompted this blog post. What she saw this month on her new Forever Amber floribunda tree rose will become relatively common in Sacramento this summer. I know I will see it on my Perfect Moment; it always shows up in August.

First, here’s Kristine’s letter:

“I’m new to roses, and recently planted five rose trees in my backyard. When I went to deadhead some spent blooms, I came across a weird growth coming from the middle! My instinct is to cut it off, but my curiosity is to keep it on to see what happens.”

Kristine attached a photo and included some details about when, where and how she planted her new tree roses. That included another clue: She added fertilizer to the planting holes and top-dressed with compost. The oddball buds showed up two weeks later.

Stress from transplanting and heat probably triggered this phenomenon known as phyllody (pronounced fil-o-dee). It also can be caused by water stress (which can be aggravated by fertilizer), disease or exposure to glysophate, the active ingredient in Round-up herbicide.

A similar condition is called fasciation (like fascination with no “n”), which results in deformed growth such as fused buds and stems. It’s also probably linked to hormones during development, and affects a wide range of plants.

UC Cooperative Extension master gardeners’ plant notes, from the university’s Integrated Pest Management website, describe rose phyllody this way:

“Rose phyllody is a flower abnormality recognized for more than 200 years in which leaf-like structures replace flower organs. The fundamental cause seems to be changes in plant hormone balance, brought about by abiotic conditions such as environmental stress, or by living infectious agents. Some rose varieties such as floribundas are more likely to exhibit phyllody symptoms, probably due to genetic susceptibility.”

Viruses and disease can disrupt hormone production and cause phyllody, add the master gardeners.

“(But) in roses, the most common cause of phyllody is environmental stress, such as hot weather when flower buds are forming, or water stress,” they explain. “If environmental factors are the cause, affected plants usually have normal and abnormal flowers simultaneously but otherwise look healthy. When the weather cools, the bush resumes producing only normal flowers.”

Those super-hot days in mid-May could have triggered Kristine’s case of phyllody. If the plant didn’t get enough water to go along with that double dose of fertilizer, the rose may have experienced some water stress, too.

In my garden, some roses are more susceptible to phyllody that others. It tends to be more common in my floribundas, but my Perfect Moment (a hybrid tea) sprouts odd buds whenever we get a long stretch of triple-digit days in summer.

The solution is easy: Prune off the odd bud and let the rose sprout another one. Given enough water (and cooler days), it should look normal.

The important thing to notice is if it’s the occasional oddball bud or the whole bush. If the weird growth is just now and then, or appears on the bush at the same time as normal roses, then it’s stress-related. If it’s the whole bush and every new bud, then the condition is more serious and likely points to virus or disease.

For more on phyllody and other rose maladies: http://ipm.ucanr.edu/PMG/PESTNOTES/pn7463.html

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GENERAL GARDENING

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Keywords:

UCCE master gardeners Sacramento roses heat stress deadheading rose diseases irrigation abiotic factors weather gardening phyllody UC IPM environmental stress flowers

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Garden Checklist for week of May 19

Temperatures will be a bit higher than normal in the afternoons this week. Take care of chores early in the day – then enjoy the afternoon. It’s time to smell the roses.

* Plant, plant, plant! It’s prime planting season in the Sacramento area. If you haven’t already, it’s time to set out those tomato transplants along with peppers and eggplants. Pinch off any flowers on new transplants to make them concentrate on establishing roots instead of setting premature fruit.

* Direct-seed melons, cucumbers, summer squash, corn, radishes, pumpkins and annual herbs such as basil.

* Harvest cabbage, lettuce, peas and green onions.

* In the flower garden, direct-seed sunflowers, cosmos, salvia, zinnias, marigolds, celosia and asters.

* Plant dahlia tubers. Other perennials to set out include verbena, coreopsis, coneflower and astilbe.

* Transplant petunias, marigolds and perennial flowers such as astilbe, columbine, coneflowers, coreopsis, dahlias, rudbeckia and verbena.

* Keep an eye out for slugs, snails, earwigs and aphids that want to dine on tender new growth.

* Feed summer bloomers with a balanced fertilizer.

* For continued bloom, cut off spent flowers on roses as well as other flowering plants.

* Don’t forget to water. Seedlings need moisture. Deep watering will help build strong roots and healthy plants.

* Add mulch to the garden to help keep that precious water from evaporating. Mulch also cuts down on weeds. But don’t let it mound around the stems or trunks of trees or shrubs. Leave about a 6-inch to 1-foot circle to avoid crown rot or other problems.

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