One of the ways by which the Plant Protection Directorate (PPD)
functions to maintain the plant health status of Malta is by monitoring the
situation and by carrying out specific surveys.
Very often, these
monitoring and surveillance operations are dictated by the provisions of EU law
in relation to plant health. Both routine and specific surveys target the
organisms that are most likely to cause damage to a plant.
Obligatory EU surveys
Obligatory EU
surveys are connected to the monitoring of pests and diseases of quarantine
concern. In fact, most of these surveys are performed in accordance to EU
Emergency Decisions and Control Directives. These surveys are divided into 5
taxonomies namely: insects, nematodes, bacteria, fungi, and viruses and phytoplasma.
The following are some examples.
Insects
• Rhynchophorus ferrugineus as
per Commission Decision 2007/365/EC and amendments on emergency measures to
prevent the introduction into and the spread within the Community.
• Leptinotarsa decemlineata this
survey is carried out to maintain a protected zone status in Malta as required
by Council Directive 2000/29/EC and amendments.
• Toxoptera citricida as per
Council Directive 2000/29/EC and amendments on protective measures against the
introduction into the Community of organisms harmful to plants or plant
products and against their spread within the Community.
• Anaplophora chinensis as per
Commission Decision 2008/840/EC and amendments and Commission Implementing
Decision 2012/138/EU as regards emergency measures to prevent the introduction
into and the spread within the community.
• Epitrix sp. As per Commission
Implementing Decision of 16 May 2012 as regards emergency measures to prevent
the introduction into and the spread within the Union.
• Scaphoideus titanus vector of
Grapevine Flavescence dorée. This survey is carried out as a proof of
the absence of the vector and the mentioned mycoplasma.
Nematodes
• Bursaphelenchus xylophilus as
per Council Directive 2000/29/EC and amendments on protective measures against
the introduction into the Community of organisms harmful to plants or plant
products and against their spread within the Community and Commission Decision
2006/133/EC requiring Member States temporarily to take additional measures
against the dissemination of Bursaphelenchus xylophilus.
• Potato cyst nematodes (Globodera
pallida and Globodera rostochiensis) as per Council Directive 2007/33/EC on
the control of potato cyst nematodes and repealing Directive 69/465/EEC.
Bacteria
• Potato Ring Rot (Clavibacter
michiganensis var sepedonicus), as required by Commission Directive
2006/56/EC amending Annexes to Council Directive 93/85/EEC on the control of
Potato Ring Rot.
• Potato Brown Rot as required by
Commission Directive 2006/63/CE amending Annexes II to VII to Council Directive
98/57/EC on the control of Ralstonia solanacearum (Smith) Yabuuchi et
al.
• Erwinia amylovora as per
Council Directive 2000/29/EC and amendments on protective measures against the
introduction into the Community of organisms harmful to plants or plant
products and against their spread within the Community.
• Xylella fastidiosa as per
Commission Implementing Decision 2015/789/EC as regards measures to prevent the
introduction into and spread within the Union of Xylella fastidiosa.
Fungi
• Phytophtora ramorum as per
Council Directive 2000/29/EC and amendments on protective measures against the
introduction into the Community of organisms harmful to plants or plant
products and against their spread within the Community and Commission Decision
2002/757/EC and amendments on provisional emergency phytosanitary measures to
prevent the introduction into and the spread within the Community.
• Gibberella circinate as per
Council Directive 2000/29/EC and amendments on protective measures against the
introduction into the Community of organisms harmful to plants or plant
products and against their spread within the Community and Commission Decision
2007/433/EC on provisional emergency measures to prevent the introduction into
and the spread within the Community.
• Tilletia indica as per Council
Directive 2000/29/EC and amendments on protective measures against the
introduction into the Community of organisms harmful to plants or plant
products and against their spread within the Community.
Viruses and phytoplasma
• Citrus Tristeza Virus as requested by
Council Directive 2000/29/EC and amendments on protective measures against the
introduction into the Community of organisms harmful to plants or plant
products and against their spread within the Community and also to maintain a
Protected Zone Status in Malta as required by same directive.
• Pepino Mosaic Virus as per Commission
Decision 2004/200/EC on measures to prevent the introduction into and the
spread within the Community.
• Tomato Yellow Leaf Curl Virus as per
Council Directive 2000/29/EC and amendments on protective measures against the
introduction into the Community of organisms harmful to plants or plant
products and against their spread within the Community.
• Tomato Spotted Wilt Virus as per
Council Directive 2000/29/EC and amendments on protective measures against the
introduction into the Community of organisms harmful to plants or plant
products and against their spread within the Community.
• Grapevine Flavescence dorée as
per Council Directive 2000/29/EC and amendments on protective measures against
the introduction into the Community of organisms harmful to plants or plant
products and against their spread within the Community.
• Plum Pox Virus as per Council
Directive 2000/29/EC and amendments on protective measures against the
introduction into the Community of organisms harmful to plants or plant
products and against their spread within the Community.
In order to review
the above-mentioned Directives of to search for more information please follow
these links EUR-LEX , EU Plant Health Rules.
National Surveys
National surveys
are done to monitor the status and situation in relation to a number of pests
of national concern. Due to trade, there has been an increased number of pests
that are present in the Maltese islands, including pests on carobs, grapevines,
tomatoes and figs. National surveys also serve as a reference base for the
drawing up of necessary guidelines and action plans to control the incidence of
these pests. Some examples of pests of national concern are described below.
Apate monachus, an insect pest found on carob trees and
grapevines
The Apate
Monachus (Fabricius 1775) beetle which is found from tropical Africa
up to the Mediterranean (northward up to Corsica, southern France and northern
Spain), is established in the Neotropical region and was intercepted in central
European countries and USA. It is very notorious and worrying as it can feed on
numerous different trees with other 80 host plants used for larval development.
Carob trees in Manikata, Armier Malta and Fontana Gozo have been targets some
of which can die rapidly. The symptoms observed are drying leaves sometimes
even to the point where the tree sheds all its leaves. Resin and round exit
holes from where the beetle exits are sometimes also observed. Adult beetles
which are also observed in Malta are nocturnal and are frequently collected at
half-light. To date the sole method for controlling this beetle is by cutting
and burning the infected parts. Any carob trees or any tree protected under LN 200 of2011 can only be pruned
or felled prior to obtaining necessary approval from the Environment and Resources Authority (ERA)
Tomato leafminer (Tuta
absoluta)
The tomato
leafminer (Tuta absoluta) pest originates from South America. It has
spread in various countries across Europe and was first reported in Malta in
2009. It is a harmful leaf mining moth with a strong preference for tomato but
which can also attack other solanaceous plants such as potatoes, peppers and
aubergines. Tuta absoluta can reproduce rapidly as one female specimen
may lay up to 260 eggs during her lifetime which are deposited on the parts of
the plant found above ground. The caterpillar lives as a miner in the leaf,
stem or fruit but usually exits the mine to pupate. Larger caterpillars can
sometimes be found outside the mine or fruit. Pupation may take place in the
soil as well as on the surface of a leaf, in a curled-up leaf or in a mine. The
moths are active during the night and hide between the leaves at daytime. For
an effective control strategy, tomato growers should install and maintain
pheromone traps for mass trap monitoring of this pest in fields and greenhouses
which are devoid of netting. In case of such greenhouses, these should have
installed pheromone traps or other mass trapping devices on the inside and
should also have installed pheromone traps on the outside distributed
throughout the perimeter. Pheromone traps should be positioned not more than 1m
above ground level and should be distributed uniformly in the greenhouse or
field. This should even go on for a forthright after harvesting with regular
monitoring of such traps. Tomato plants infected with Tuta absoluta should
be treated with the appropriate insecticides which are registered with the national
competent authority for use on
tomatoes against the pest, and appropriate records of pesticide used should
also be kept.
Fig tree borers
Hypocryphalus
scabricollis: This species was
discovered over a hundred years ago in Burma in Asia and was recently
introduced in Malta probably through a cultivated Ficus. In the last 3-4 years
this insect began reproducing on healthy fig trees attacking the main stems not
just the thin branches of the tree. This insect is causing major damage in fig
tree species namely bajtar ta’ San Ġwann, farkizzan and dukkar
where unfortunately a number of dead trees have already been reported.
Hypoborus ficus: This beetle, which causes a kind of rot, is
spread across Europe, North Africa and in Eastern areas. This species usually
attacks diseased or dry branches of fig tree species. This beetle is very
common in the Maltese islands and was also recorded on other trees and vines.
This beetle (susa) is very small and is noticeable due to the very small
holes which it bores into the bark of the fig trees. These holes resemble
puncture wounds caused by a needle. This beetle attacks both trees which are
weak and drying as well as healthy trees.
According to a
recent study it was found that both Hypocryphalus scabricollis and Hypoborus
ficus have been causing damage in fig trees. Both are small insects which
are barely visible (millimetre size). The best method of dealing with infestations
is to eliminate the infected branches/stems which are burnt immediately to avoid
further spread to other trees. During the winter months it is recommended to
spray the trees with copper sulphate and if any lesions are spotted on the main
stems these are to be coated with copper. It is very important that dead trees
are burnt immediately since the rot continues to multiply within the dead
stems.