News & Observer | newsobserver.com | Weapons fight camellia blight

Published: Mar 20, 2004 12:30 AM
Modified: Oct 24, 2005 09:41 AM

Weapons fight camellia blight

The lovely Camellia sasanqua 'Yuletide' could turn ugly if petal blight, caused by a fungus, takes hold.

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For camellia growers, 'tis the best of times and possibly the worst of times. Camellias -- in particular, Camellia japonica -- are blooming their branches off. (Particularly since winter seems to have loosened its icy grip on the garden, fewer displays are being blemished by frosts or subfreezing temperatures.)

However, there could be trouble in paradise. Instead of enjoying pristine displays of flowers, some camellia gardeners might find blossoms tainted with brown spots that enlarge and eventually turn what could have been minor botanical masterpieces into works that can only be described as junkyard dog ugly.

The ailment is petal blight, caused by the fungus Ciborinia camelliae, and, in this area, it can be quite common on camellias.

An infected blossom quickly turns completely brown within a matter of days, dies and falls to the ground. After death, there is life, but, in this case, it is not necessarily good. At the base of infected flowers, the infringing fungus produces black, hard, fruiting bodies called sclerotia that drop to the ground with the blighted blossom.

The sclerotia can remain dormant in the soil for up to five years, just waiting for conditions to be right. These conditions include high humidity, frequent rain showers and mild temperatures during bloom time -- all of which are not strangers to our neck of the woods in the late winter and early spring. Once stirred up, sclerotia produce small, mushroomlike structures called apothecia that release tiny spores into the garden, into the wind and into gardens beyond.

It seems to be an unending cycle that can make it tough to enjoy pristine camellia flowers. However, remedies are available.

The chemical fixes

Commercial chemicals can cut down on the problems associated with petal blight. A fungicide containing Mancozeb -- used as a foliar spray right after the blooms begin to show color and applied every 10 to 14 days at repeated intervals during the flowering season -- can offer some control against this funky fungus.

Also, a soil drench of a fungicide laced with ferbam or captan could help prevent the development of the spore-producing apothecia. The fungicide should be applied underneath the camellia and on at least a 10-foot radius around the plant in early November with repeat treatments through the bloom season.

The nonchemical fixes

For the gardeners who, just by their very nature, don't like fooling with Mother Nature and commercially concocted solutions, there is a natural option that can be more effective than commercial fungicides. It involves interrupting the life cycle of the fungus.

Because a lot of the fungi's development takes place in the planting medium underneath the camellia, break up the party by putting metal to the petals. Rake up the spent blooms as they begin to carpet the ground. I know, a layer of freshly fallen petals can be a beautiful sight. But they are also a potential breeding ground. So, get a camera, capture the moment and then rake them up.

Don't compost the spent petals unless you know you can heat your compost pile to at least 140 degrees Fahrenheit. That's how hot it needs to be to destroy the Ciborinia fungus. And because petal blight spores can be carried up to a mile in the wind, the best way to deal with the pestilence is to bag the petals up and toss them in the trash.

In the spring, the winter mulch around camellias should likewise be raked up, bagged and discarded. This should be followed by adding a 1- to 2-inch layer of spring mulch in its place, which, after it has done its duty, should be similarly sent off to the dump in the late fall.

Petal blight is a tough problem to completely get rid of. But if you continue to police the growing ground around your camellias, it can be controlled, leading to better displays of dazzling flowers to herald the coming of yet another spring.

L.A. Jackson, editor of Carolina Gardener magazine, can be reached at lajack@lycos.com. Carolina Gardener is online at Get $150+ in coupons in every Sunday N&O. Click here for convenient home delivery.

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