In Georgia landscapes, azaleas practically sing spring. So do
rhododendrons in much of
the state. But this year, many people are finding dead branches
in both of these prized
ornamentals.

“We’ve had a number of samples come into the lab,” said Jean
Williams-Woodward, a
plant pathologist with the University of Georgia Extension
Service. “So far, we’re finding
two main causes of the branch dieback.”

The less serious of the causes, she said, are fungal diseases
that got into the branches
through some kind of wound.

“We had a warm fall last year,” she said. “Many shrubs weren’t
properly hardened off yet
when we had a sudden cold snap in December. That caused some
bark splitting in some
tender branches.”

A long, mild spring then complicated the problem, allowing fungi
to infect the wounds the
cold snap left. The main culprits, she said, are Phomopsis in
azaleas and Botryosphaeria in
rhododendrons.

“These fungi get in and cause a canker — a sunken, dark brown,
grayish area,”
Williams-Woodward said. “Sometimes they can girdle the stem. And
when that happens,
the branch dies.”

Sometimes a single fungal canker won’t girdle a stem, she said.
But two or more on the
same stem can produce the same result.

Once these fungal cankers have girdled a branch, she said, you
can’t save it. But you can
spare the rest of the shrub. Just prune out the dead branch and
keep the plant properly
mulched and watered to reduce stress.

Sometimes, though, the problem isn’t contained with the
branch.

“The more serious problems we’ve seen are root rots,” Williams-
Woodward said. “These
are caused by fungi, too. But they’re the result of poorly
drained or compacted soils.”

You can tell the difference, she said, by cutting along the
branch. If the dead, cankerous
tissue isn’t contained within the stem but goes to the base of
the plant, the problem is root
rot.

And the remedy isn’t so simple. The first step is to remove the
plant — it isn’t going to
survive.

“Then change the drainage,” Williams-Woodward said. “Raise the
bed, or amend the soil.
You have to make the site drain better, or the next plant won’t
fare any better.”