Fall Is Good Time to Find Buckthorn
John Church, Natural Resource Educator, Rockford Extension
Non-native, exotic buckthorn plants have been known to be a problem
in wooded and other natural areas for a number of years, due to
their competitive nature. However, in the past year, it has been
found that they also can be host to the soybean aphid, a new field
crop pest. Exotic buckthorn varieties have been introduced to
North America as ornamental shrubs. There are also native buckthorn
species in Illinois, but they are less competitive.
During the summer and autumn of 2000, the soybean aphid was observed
in Midwestern states. Some of the heaviest infestations were observed
in northern Illinois. U. of I. entomologists also found the aphids
present in soybean fields this year. The aphids feed on soybean
plants and can cause stunting and reduce pod set. It has been
determined that at least two types of exotic buckthorn plants
are overwintering hosts for the aphids. Researchers are continuing
research on the types of buckthorn that act as hosts, their typical
distribution, and the degree of involvement with soybean aphid
infestations in fields. Buckthorn plants do not invade soybean
fields, but can be common around field edges.
In wooded or other natural areas, exotic buckthorn species shade
or crowd out native vegetation. When the desirable, low growing
plants are lost, bare soil is often exposed and susceptible to
excessive erosion, especially on slopes and near streams and rivers.
The competitive buckthorn plants can also choke out bigger shrubs,
which reduces food supplies for wildlife and creates dense barriers
for humans and animals to travel through.
Now is a good time to identify buckthorn, since it is one of
the last shrubs to lose their leaves in the fall, it stands out
more easily. Buckthorn control can be done with herbicides or
controlled burns. Researchers at the Illinois Natural History
Survey indicate that regular prescribed burning is the preferred
method when feasible. This may be especially true for areas with
abundant numbers of plants. Proper burning permits and safety
control measures should be in place before burning. For isolated
plants, herbicide treatments may be the most feasible.
For further information on buckthorn, its control, or the soybean
aphid, contact your local University of Illinois Extension office.