I have something going on that is killing some of my roses. An apparently healthy plant will get an entire cane that yellows, withers, and dies. Canes typically brown right at soil level. This is not just freshly planted bushes, some of the effected plants have been in the ground two or more seasons. We’ve had an unusually hot and humid summer, but I’ve been monitoring soil moisture, checking a finger depth to be sure there’s still moisture an inch or so down. Also, treat with fungicide every other week.
As for fertilizer… early spring I gave each bush about 1/4 cup of dried manure from my chicken coop. Spread this around just before a good rain when the weather was still cool and growth just starting, being careful not toget any on the leaves or sprouts. Then May 1, each plant got 1/4 cup of a 2:1 blend of 12-12-12 and Milorganite sprinkled around the base of the plant - again careful not to get it on leaves or sprouts. Repeated this 2?1 blend on July 1.
The only thing that comes to mind is that perhaps something in your soil is eating away at the roots. Bu that is just an uneducated guess. You don’t say what area you live in. Could it be nematodes, moles or voles?
I’ve had the same issue for a few years now. Thought I was losing my Hansa but it’s been coming back. Now the issue has moved to another bed with Dagmar Hastrup. Both are HRg that I’ve had for 20 years. I have no answer, just empathy.
I’m thinking it is voles. I’ve used wood chip mulch for years to keep moisture in and weeds down, and I read that the creatures like mulch too. I’ve got small holes throughout the garden. I thought this was either chipmonks or possibly snakes… spot gardener snakes regularly thoroughout the yard.
Here’s a couple of pictures. Holes are a little smaller than the size of a golf ball.
I just went out to check Hansa. Here’s the pic of this year’s cane – short, yellow and on the ground. (Ignore the Japanese beetle damage on the blooms.)
I had holes in my garden, probably five years ago. All I ever found in them was toads…but here is the latest dead cane discovery – Savannah (HT). That’s the base of the cane. It looks like the bark is chewed off and it’s girdled. I was blaming my son’s German shepherd, maybe he was going after voles?
Set out a few snap traps with peanut butter….. caught a few culprits last night! One looks like a mouse, the other maybe a mole? I’ve also just put in a few of the buzzers that supposedly scare off the critters by emitting sound into the ground. We’ll see if those do any good. Also, expecting to get two new outdoor cats this weekend…. hopefully this three pronged attack will convince the critters to move out of my rose bed. Apparently a nice fluffy soil with a mulch top dressing, is very appealing to these varmits.
Voles are a good possibility and the German Shepherd would be attracted to catching them. Voles can be very problematic, especially if the roses are near any wooded areas. Some rosarians plant them in ‘cages’, like Vole King, to prevent them from eating the lower canes and roots.
Doubt if is voles because I live on rock and therefore have nothing like that. As for extra moisture, I live in south Texas so that is ruled out. But we have been seeing the same problem
Mice will also eat the cambium of shrubs (including roses) causing the same scarring/callusing as shown in the original photo. Something is eating the cane causing it to callus like that to seal the wound. Once the cambium (circulatory system) is severed, the cane above the damage dies. Flat Head Apple Borers cause similar damage but I see no frass (the “poop” from borers or other insects) in the damaged cane. The Flat Head borers leave a frass resembling cocoa powder in their bore paths. Their damage also results in the callusing you see in that photo. If the dying canes present that damage, it’s physical from either critters or insects.
Yes, I ran a fresh soil test. Nothing exceptional other than I need to up the potassium. BTW, with new rooted cuttings, ,I am planting them in home-made hardware cloth cages. Plus we have two outdoor cats now on patrol, so I expect to get regular presents of dead moles/voles in the driveway.
