Tuesday, April 22, 2014

To Bee or Not to Bee

Bee on golden currant
Nature provided us a natural controlled experiment in our Springfield backyard. Several years ago, Barb planted a small native golden currant in it.  The shrub is growing beside an established forsythia, a common non-native ornamental.

Golden currant on left next to forsythia

Last week we noticed bees buzzing around the deck.  They were all over the golden currant, slurping up its nectar while totally ignoring the larger blossoms of the forsythia.  Just like us, bees and other pollinators have their food preferences and they have never developed a taste for many of our exotic plantings.

Golden currant
Golden currant's, Ribes odoratum, blossoms may be slightly smaller than forsythia, but they make up for it with colorful red petals encircled by yellow sepals.  It is also known as clove currant for its strong sweet clove-like odor which is detectable several feet away, hence the species name odoratum.  It is typically found in southern Missouri on exposed high rocky limestone bluffs above the Current and White Rivers.  The fruits which are full of seeds were eaten by settlers and and natives.

Golden Currant
Golden currant is available from the MDC's George O. White Nursery in Licking.  Because of its decorative value, it has been cultivated and now has escaped in some states to the east. 

"One man's ceiling is another man's floor." - Paul Simon

At first glance this would seem to be a desirable spreading species, colorful, fragrant and supporting pollinators.  So why is it banned to some degree in 14 Eastern states?  When growing in these regions as an exotic species, it is an alternate host of white pine blister rust fungus, a disease which doesn't affect our native short-leaf pine trees in Missouri.

Like the cedar apple rust gall we see in Missouri, white pine blister rust fungus Cronartium ribicola, has a complex life cycle requiring two separate types of host plants.  It is an invasive from either Europe or Asia, visiting the US around 1900 and liking the naive species of pines it found here.  Before attacking pines, it requires currants and gooseberries to support its earlier stage.  The significant damage it does to susceptible pine species has led to the golden currant bans.

So is golden currant a good or bad choice for decorative planting?  As usual, when faced with good-bad decisions, the answer is "it depends."  For Missouri where it is native and beneficial it is a great plant.  The key is in the phrase you are seeing all over Missouri, "Grow Native."

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