This blog is devoted to increasing the awareness of our natural world and to the people working to conserve it. Approximately every four weeks, you’ll have the opportunity to vicariously follow along with David Cordray and discover the beauty, excitement, wonderment, and sometimes tragedy of our natural world.

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Seeing Orange

My left leg, bound by black raspberry canes, refuses to move, and I suddenly find my upper body, propelled forward by a heavy backpack sprayer, without support. I’m going down; I gasp, shut my eyes, and bring my arms upward to cradle my head. My foot pulls free of its captive rubber boot, left shoulder crashes into the ground, body slides downhill through the clawing bramble patch, and I finally come to rest entangled in dozens of prickly canes. Ready to let loose with choice expletives, I open my eyes and see orange covering the undersides of some berry leaves. My boiling rage is quickly displaced with the seductive satisfaction of sweet revenge!

Often, shortly after invasive woody species (shrubs and trees) are removed from degraded oak savannas and open oak woodlands, brambles will fill in the ground layer in dense, impenetrable patches. Brambles can also invade prairies, especially in areas that receive some shade from nearby trees. Species such as dewberry, red raspberry, black raspberry and blackberry quickly respond to the clearing disturbance and colonize the ground layer leaving little room for more desirable herbaceous plant species. These bramble thickets can persist for years, delaying our restorations efforts in establishing a diverse ground layer.

Two of these bramble species are especially troublesome. Black raspberry, which I nickname Rubus loopis, for its ability to root at both ends of the cane effectively creating a very efficient trip hazard. And blackberry, which forms massive tall canes armored with hooked daggers. I receive a lot of inquiries from frustrated landowners on how to get rid of these two species. Most folks are okay with having a few of these plants around. Who doesn’t like eating blackberries or black raspberries? But thick patches must go.

Unfortunately, on a landscape scale, there aren’t easy solutions for a fast fix. Herbicide control, such as cutting and treating stems, spot spraying re-sprouts and foliar spraying dense patches, can be effective on a smaller scale. But in all cases, care is needed in application and good plant identification skills are essential to ensure you don’t kill the plant species you want to prosper.

My approach to bramble patches is to either burn them or cut them each year. Burning and cutting resets the brambles allowing other plant species a chance to compete. Long-term plant competition is key to muscling out the brambles’ dominance.

In addition to cutting or burning annually, there’s a Mother Nature provided tool that will accelerate the decline of the bramble patches – orange rust.

According to Cornell University’s College of Agricultural and Life Sciences, orange rust is a disease that affects both black raspberry and blackberry. There are two forms. The form on black raspberry is caused by a fungus known as Arthuriomyces peckianus, while the form more common on blackberry is known as Gymnoconia nitens. Orange rust invades the entire plant, reducing blossoming and fruit set. Although orange rust doesn’t kill plants, it’s systemic in the plant and heavily infected plants are of no commercial value. They will not recover and unless destroyed, will persist as a source of inoculum that may spread the disease to additional plants.

My experience with the rust is it greatly weakens its host as it tries to grow back in the spring. The fungus spores appear as an orange powder on the undersides of leaves in June. Affected plants eventually drop their diseased leaves and grow a short branch of new leaves later in the summer. The result is a delayed and stunted growth of the Rubus species, giving an additional competitive advantage to neighboring plants. This past spring was an excellent year for the black raspberry orange rust. In early June, I found it on several properties. I found smaller amounts of blackberry orange rust in mid-June.

I sit up and carefully untangle the thorny brambles wrapped around my body. Thankful my backpack did not leak herbicide, I scoot uphill on my knees and retrieve my boot. With boot in place, I stand up. I taste blood and feel a burning sensation on my lip and nose. Other than a few facial scratches and more bruises, I’m okay. I pull off several of the leaves from the affected plant covered in orange rust, smear the rust all over my chaps, and plow my way through hundreds of healthy black raspberry canes.

It’s payback time!

orange rust on black raspberry - image by David Cordray

orange rust on black raspberry - image by David Cordray

orange rust on blackberry - image by David Cordray


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