1-7 December 2003
Installment #200--Visitor #

All text & photos © Hilton Pond Center


Black Cherries, Prunus serotina, lead a tough life at Hilton Pond Center and elsewhere across the Carolina Piedmont. In spring tens of thousands of Eastern Tent Caterpillars build silken webs in their branches (below right), from which they conduct feeding forays that strip the trees bare of tender green leaves. Most trees rebound from this defoliation, but heavy infestations several years in a row can sap a tree's strength and eventually kill it. Other insects attack the tree's buds while some species bore into its cambium layer. White-tailed Deer and small mammals such as Eastern Cottontails and Pine Voles consume the bark at ground level--a devastating problem for cherry seedlings and small saplings. Perhaps the most obvious and pervasive enemy of Black Cherry, however, is one whose handiwork is easily seen throughout the winter woods: Apiosporina morbosa, the Black Knot Fungus.

Black Knot disease causes thick, dark swellings on cherry twigs that look for all the world like--how can we put this delicately--elongated animal droppings hanging in the tree (top and below). In fact, many times on field trips we've had students who initially wouldn't pick up a cherry twig infested with Black Knot because they thought it was some form of scat--a polite word for feces. Their coprophobia was groundless, however, because the dark matter is actually the tree's own cells gone haywire because of the fungus.

Black Knot usually starts as an olive-green swelling at the base of a leaf petiole, but it eventually enlarges and turns dark. Smaller Black Cherry twigs that are attacked by the fungus usually perish within a year or so, and young trees with sizeable infestations often wither and die when the Black Knot growth interferes with transmission of water and minerals up from the roots and food products down from the leaves. Huge swellings occur even on the trunks of large trees, and these may or may not lead to the host's demise. Obviously, such malignant growth makes the tree worthless for lumber purposes, but at least the sap that oozes from the cankerous sores may provide nutrition for a variety of birds, butterflies, and small mammals.

Although the bark of young Black Cherry trees is relatively smooth, it is marked by distinctive thin horizontal lines called "lenticels"--tiny pores that apparently function in gas exchange. In older trees the outer surface becomes dark and crinkly, but at any age the species is still easy to identify up close by looking at its bark. Remarkably, the Black Cherries around Hilton Pond often can be spotted hundreds of feet away--not from of their bark characteristics but because their trunks and twigs are so heavily scarred by Black Knot disease (above left and below).

It's unfortunate that Black Knot is so pervasive on the Black Cherries at Hilton Pond Center. Since the fungal spores are spread by wind and rain, there's not much one can do to stop transmission from one host to the next. Our numerous cherry trees are unlikely to achieve championship size under the on-going assault from insects and fungi, but at least those students who once wouldn't touch a Black Knot canker can use the disease to identify a Black Cherry with great accuracy. Before they get too confident, however, we should remind our young naturalists that that our shrubby native plums at Hilton Pond Center are likewise affected by the same fungus that causes Black Cherry Knot.

All text & photos © Hilton Pond Center

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"This Week at Hilton Pond" is written & photographed
by Bill Hilton Jr., executive director of
Hilton Pond Center for Piedmont Natural History.

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Oct 15 to Mar 15
Please report
your sightings of
Vagrant & Winter

1-7 December 2003

Northern Cardinal--1
Purple Finch--4
White-throated Sparrow--1
House Finch--1
Eastern Towhee--1

* = New species for 2003

5 species
8 individuals

61 species
1,037 individuals

(since 28 June 1982)
123 species
43,151 individuals

(with original banding date, sex, and current age)
Northern Cardinal (1)
01/21/02--after hatch year male

White-throated Sparrow (2)
04/20/00--after 4th year female
11/26/01--after 2nd year unknown

All text & photos © Hilton Pond Center

--On the morning of 2 Dec, eight Wood Ducks--four drakes and four hens--were cruising Hilton Pond. One drake was especially attentive to one of the females.
White-throated Sparrow trapped on 5 Dec was the 1,700th individual of its species banded at the Center since 1982. White-throats are the seventh most commonly banded local species.

--A hatch-year female Rufous hummingbird was banded on 5 Dec at Rock Hill SC, and a young male Rufous was banded the following day at Gastonia NC.

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Hilton Pond Center for Piedmont Natural History is a non-profit research & education organization in York, South Carolina USA; phone (803) 684-5852. Directed by Bill Hilton Jr., aka "The Piedmont Naturalist," it is the parent organization for Operation RubyThroat. Contents of this website--including articles and photos--may NOT be duplicated, modified, or used in any way except with the express written permission of Hilton Pond Center. All rights reserved worldwide. To obtain permission for use or for further assistance on accessing this website, contact the Webmaster