One of the most common questions new rose growers ask is, “Is this new growth, or is it rose rosette disease?” It’s a fair concern. Rose rosette disease can be alarming due to its aggressive nature, and understanding the difference can save a lot of stress. Fortunately, as Paul Zimmerman explains, you don’t need specialized tools to tell the difference. You already have everything you need right in your own garden.
In this guide, we’ll explore the key differences between new rose growth and rose rosette disease so you can confidently identify what’s happening in your garden.
The Common Concern: Why the Confusion?
Rose growers are often taught that reddish or purple new growth is a potential sign of rose rosette disease. However, this color is typically caused by anthocyanins—a natural pigment produced in young plant tissue—and is perfectly normal for healthy growth. While this color can be a symptom, it isn’t enough on its own to confirm the disease. Healthy new growth on roses often has a reddish tint as well, which is perfectly normal. So how do you know for sure? By comparing new growth to the older, established growth on the same plant, you can spot telltale signs that set rose rosette disease apart from healthy growth.
Let’s break it down into three simple checks. To follow along in the video, here’s the link:
1. Look at the Leaves: Shape and Structure
The first sign to examine is the shape and structure of the leaves. Rose rosette disease, caused by the Rose Rosette Virus (RRV), is characterized by misshapen foliage, often twisted, distorted, or excessively elongated. This is very different from the normal variation seen in healthy new growth.
- What to Do: Compare the leaves of the new growth to the older, mature foliage on the same plant.
- What to Look For:
- Healthy new growth will have leaves that are similar in shape to the older growth, even if they are a bit redder or slightly thinner.
- With rose rosette disease, the leaves will look visibly distorted compared to the mature growth.
As Paul demonstrates, side-by-side comparisons are key. If the leaf shape matches, you can rule out rose rosette disease for this particular growth.
2. Check the Thorns: Quantity and Shape
The next feature to inspect is the thorns. A classic symptom of rose rosette disease is something called hyperthorniness. This means an excessive number of thorns appear, often in irregular patterns.
- What to Do: Compare the thorns on the new growth to the established growth.
- What to Look For:
- Healthy new growth may have slightly more thorns than older canes. This is normal.
- However, rose rosette disease causes thorns to become extremely dense and irregular. If the thorns appear in much greater numbers or look unnatural compared to older canes, this could be a red flag.
Additionally, pay attention to the shape of the thorns. On healthy growth, the thorns will maintain the same general structure and direction as the older growth. In cases of rose rosette disease, thorn shapes may appear abnormal.
3. Inspect the Canes: Shape and Growth Pattern
Lastly, examine the canes themselves. Rose rosette disease often causes canes to become flattened or otherwise misshapen, which is a clear departure from healthy growth.
- What to Do: Look closely at the structure of the canes, comparing new growth to the mature canes.
- What to Look For:
- Healthy new growth will have canes that are round and consistent in shape, even if they vary slightly in thickness.
- With rose rosette disease, canes often appear flattened, contorted, or irregular.
If the canes on the new growth look normal compared to the older parts of the plant, this is another sign that what you’re seeing is healthy new growth.
Tools You Already Have in Your Garden
As Paul emphasizes, the most valuable tool you have is the established growth on your rose plants. By comparing new growth to mature growth, you can identify:
- Leaf Shape: Is it consistent with mature foliage?
- Thorn Quantity: Are there a normal number of thorns?
- Cane Shape: Does the cane remain round and natural?
These simple comparisons will help you confidently determine if what you’re seeing is healthy new growth or something more concerning like rose rosette disease.
When in Doubt: Seek Advice
If you’re still unsure after inspecting your roses, don’t panic. As Paul encourages, reaching out to knowledgeable communities can provide clarity. Additionally, consider consulting local extension services or a plant pathologist, as they can offer reliable, expert-backed identification of rose rosette disease. For additional information, you can refer to resources like the Oklahoma State University Extension Guide. Online groups, such as Facebook discussion forums dedicated to roses, are great places to post clear photos and ask for help. Many experienced rose growers and enthusiasts are happy to share their insights.
Final Takeaway
For many rose growers, distinguishing between new growth and rose rosette disease can feel intimidating, especially early on. However, by using the tools you already have—your plants’ own mature growth—you can easily compare and spot the differences. Remember:
- Healthy new growth may appear reddish but will have consistent leaf, thorn, and cane structure.
- Rose rosette disease presents clear symptoms like distorted leaves, excessive thorns, and flattened canes.
The next time you see reddish growth on your roses, don’t panic. Simply compare it to the established growth, and you’ll likely find that it’s perfectly normal. And if you’re unsure, don’t hesitate to ask for help.
As Paul Zimmerman reminds us, asking questions is how we learn—and learning to spot these differences will make you a better, more confident rose grower.
Paul Zimmerman is the founder of Paul Zimmerman Roses, dedicated to the philosophy that “Roses Are Plants, Too.” With decades of hands-on experience, Paul specializes in all kinds of roses but particularly antique, shrub, and David Austin roses. A sought-after designer, consultant and educator, he designs sustainable rose gardens for private clients and public institutions both in person and virtually
