Biology Reference
In-Depth Information
Fig. 3.1
Berberis vulgaris
(European barberry) was nearly eradicated between 1918 and 1978
across a huge swath of the wheat-growing regions of the US (area enclosed in
heavy black out-
line
). A smaller, but equally effective campaign was conducted between 1944 and 1978 in eastern
Washington, including Whitman County (inset). A Whitman County re-survey in 2002-2003
detected only nine plants in 100 sites where barberry had last been seen pre-1978 (Foster 2003)
(Hutton 1927). With a thoroughness that seems astounding today, teams from the
Barberry Eradication Program searched every town, village, hamlet, and the area
around all farm dwellings as well as walked along the boundaries of all agricultural
fields, searching for barberry. More than 2.0 × 10
6
km
2
were eventually searched.
Once a plant was found, it was promptly removed. In the Program's beginning,
plants were destroyed by excavation, even by dynamite (Kempton 1921)! Kerosene
and rock salt - crude tools by today's standards - were also employed (Morris and
Popham 1925). Furthermore, the investigators knew that a single reconnaissance
through an area that had supported barberry was unlikely to detect all plants; bar-
berry adults are 1-2 m tall, but seedlings can easily escape detection. Consequently,
each land parcel from which barberry had been removed was thoroughly examined
on a routine basis that stretched over years - long enough that initially missed seed-
lings grew and became conspicuous (Kempton 1921) (Fig. 3.2).
Excellent recordkeeping was essential to safely release parcels from further
inspection, thereby marshalling the hunt for remaining plants. Working without
aerial photographs, the teams prepared detailed hand-drawn maps of farms; each
building and the location of each barberry removed was indicated as an aid to resur-
veys. The recordkeeping also included tallies of the plants destroyed (> 99,000,000
by 1967) (Roelfs 1982); as these numbers rose, the incidence of stem rust fell. By
1950, the incidence of stem rust on cereals across this middle third of the US had
plummeted (Campbell and Long 2001).
Despite the extraordinary diligence in the Barberry Eradication Program, it fell
short of its ultimate goal;
B. vulgaris
still occurs in the US, even though sale of stem
rust-susceptible varieties of European barberry have been prohibited for 80 years.
