Before 1877 no legal measures were available in the UK to prevent
importation of plants infested with pests such as Colorado beetle.
Measures taken at ports from that year onwards were brought together
in the 1927 Destructive Insects and Pests Acts, empowering government
officials to inspect and, if necessary, refuse plant imports. Within
this Act, the ‘Sale of Diseased Plants Order’ placed on the grower
the responsibility for recognition and reporting of serious pests and
diseases, such as blackcurrant gall mite and silver leaf of plums. Lack
of education and enforcement led to the need for specific orders relevant
to particular current problems, such as in 1958 the fireblight-susceptible
pear cultivar, ‘Laxton’s Superb’, was declared notifiable and prohibited
under the Fireblight Disease Order.
Recent orders have helped prevent outbreaks of white rust on
chrysanthemums, plum pox virus and two American leaf miner species;
less success has been achieved with the Western flower thrip organism.
Further importation legislation under the ‘1967 Plant Health Act’
prohibits the landing of any non-indigenous pest or disease by aircraft
or post, and the ‘Importation of Plants, Produce and Potatoes Order 1971’ specifically names prohibited crops, such as plum rootstocks
from eastern Europe, crops without a phytosanitary certificate, such as
potato tubers from Europe, and crops that first need to be examined by
inspectors, such as Acacia shrubs and apricot seeds.
The carrying out of these orders is supervised by the Plant Health
Branch of the Department for Environment, Food and Rural Affairs
(DEFRA). Complete success in preventing the introduction of damaging
organisms may be limited by dishonest importations and by the
difficulty of detection of some diseases, especially viruses. European
Council directives, such as 77/93/EEC and 2000/29/EC, are moving
member nations towards a unified approach in reducing the transfer of
infected plant material across national boundaries, and the UK Plant
Health Order (2005) implements the EC legislation. The Weeds Act
1959 places a legal obligation on each grower to prevent the spread of
weeds such as creeping thistle, spear thistle, curled dock, broad-leaved
dock and ragwort. In addition, under the UK Wildlife and Countryside
Act (1981), it can be an offence to plant Japanese knotweed (Polygonum
japonicum) and giant hog-weed (Heracleum mantegazzianum).