International Plant Protection Convention
2009-003(Annex 2) – Forest Tree Seeds (DRAFT Rev2)
2009-003 (Annex 2)
Agenda item: 4.3
INTERNATIONAL MOVEMENT OF SEED: ANNEX 2 – FOREST TREE SEEDS
(DRAFT REV2)
Status box
This is not an official part of the standard and it will be modified by the IPPC Secretariat after adoption.
Date of this document
2016-05-26
Document category
Draft Annex 2 to Draft Seed ISPM
Current document stage
2016-06 To be reviewed by TPFQ
Major stages
2006-11 SC added topic: Reducing pest risks in the international
movement of seeds of forest tree species (2006-032)
2007-03 CPM-2 added topic
2007-07 TPFQ developed draft text
2008-11 SC approved specification 47 (Reducing pest risks in the
international movement of seeds of forest tree species) (2006-032)
2010-03 CPM-5 added topic: International movement of seeds (2008-003)
2011-05 SC approved Specification 54 (International movement of seed)
(2009-003).
2011-11 The SC proposed deletion of the topic International movement of
forest tree seeds (2006-032). The SC incorporated this topic into the
topic International movement of seed (2009-003)
2012-03 CPM-7 removed topic: International movement of forest tree
seeds (2006-032)
2013-07 Expert Working Group (EWG) met and drafted ISPM
International movement of seeds (2009-003)
2013-10 SC requested TPFQ to further review and draft the annex on
Forest tree seed to the draft ISPM International movement of forest
tree seeds (2006-032) (2013_eSC_Nov_11)
2014-05 SC approved draft ISPM for member consultation
2014-07 member consultation
2015-02 Steward reviewed member comments and revised the draft
2015-05 SC-7 reviewed the draft (did not recommended for 2015 SCCP)
2016-01 Assistant steward and steward reviewed comments of members
and SC and revised the draft
2016-05 SC-7 revised the draft and approved for the Second consultation
Treatment lead
2008-11 Fuxiang WANG (CH, Lead Steward)
For the draft ISPM International movement of forest tree seeds (2006-032):
2010-04 SC: Mr David PORRITT (AU, Lead Steward)
2011-05 SC: Mr Marcel BAKAK (CM, Assistant Steward)
2012-04 SC: Ms Soledad CASTRO-DOROCHESSI (CL, Lead Steward)
2012-04 SC: Mr David PORRITT (AU, Assistant Steward)
2012-11 SC: Ms Julie ALIAGA (US, Assistant Steward)
2012-11 SC: Mr Motoi SAKAMURA (JP, Assistant Steward)
2013-11 SC: Ms Julie ALIAGA (US, Lead Steward)
2013-11 SC: Ms Soledad CASTRO-DOROCHESSI (CL, Assistant
Steward)
2014-11 SC: Mr Ezequiel FERRO (AR, Assistant Steward)
2015-05 SC: Mr Nico HORN (NL, Steward)
Secretariat notes
International Plant Protection Convention
Page 1 of 8
2009-003 (Annex 2) (4.3)
Forest Tree Seeds (DRAFT Rev2)
[Note: This annex is currently under development. According to SC e-decision 2013_eSC_Nov_11, the Technical
Panel on Forest Quarantine (TPFQ) was requested to consider the information from this draft annex for review and
further drafting.]
[1]
The great majority of seeds involved in international trade are agricultural or horticultural; forest tree seed has not
featured prominently in national phytosanitary regulations and national plant protection organizations programs.
[2]
However, over the last few decades, many afforestation and reforestation programmes worldwide have resorted to
the use of exotic tree species from proven seed sources
[3]
In addition seeds for producing trees for ornamental purpose are traded world wide and this material often does not
follow the same restrictions as tree seed for commercial forestry use even though they can still pose a substantial
risk for spreading regulated pests harmful for trees.
[4]
The international movement of tree seed of species with broad e tolerances to environmental changes that may
result from climate change can also increase the spread of seed-associated regulated pests
[5]
Historically, seed imports for forestry have had a focus on quality standards of seed purity, germination capacity
and seed provenance; there has been less emphasis on the risks of regulated pests.
[6]
These factors have significantly increased The movement of forest tree seed across international borders and
therefore increased the risk of transferring regulated pests of phytosanitary concern.
[7]
Forest tree seeds can be distinguished in two categories: orthodox seeds and recalcitrant seeds. Orthodox seeds
can survive desiccation to 5% moisture content. Recalcitrant seeds, in contrast are unable to tolerate desiccation
and need to keep their moisture content on a high level (e.g. > 40% Quercus robur and Q. petraea, > 24% Acer
pseudoplatanus, xxxxxx???? 96-98%). Because moisture is an important factor for pest infestation and survival,
these categories differ in pestrisk through all stages of seed handling, from collection to storage and sowing
[8]
Table 1 Examples of tree genera with orthodox and recalcitrant seeds
Orthodox
Pinus
Fagus
Fraxinus
Betula
Abies
Platanus
Acacia
Tecona
Eucalyptus
Casuarina
Terminalia
Acacia
Ceiba
Recalcitrant
Aesculus
Quercus
Acer
Castanea
Araucaria
Hopea
Hevea
Garcinia
Pycnanthus
Intermediate
Azadirachta
Coffea
[9]
1. Seed collection stands
[10]
.
[11]
1. Collection:
[12]
Forest tree seeds are collected in a variety of ways: directly from trees through picking or shaking, from fallen fruits
on the ground, from the crown of felled trees, from animal caches of fruits (e.g. conifer cones) and these may affect
pest status of the seeds. Where there is a choice of collection methods, minimizing pest infestation should be a
consideration. Seeds should be inspected and washed or treated as required by the importing country to reduce
pest incidence.
[13]
Seed protection on the tree is difficult. However, prevention from and mitigation of pest attacks can be controlled
by:
[14]
- Advance monitoring of the crop from the flowering, fruiting to the maturity stages to ensure timely seed collection
(Phenology studies)
[15]
- Advance monitoring of the crop from the flowering, fruiting to the maturity stages to ensure timely seed collection
(Phenology studies)
Page 2 of 8
International Plant Protection Convention
Forest Tree Seeds (DRAFT Rev2)
2009-003 (Annex 2) (4.3)
[16]
- Knowledge of potential seed-related pest problems on a specific tree species and an understanding of the
biologies of the pest concerned can be used to develop effective mitigation strategies.
[17]
- collection from registered seed stands (if delete “1. Seed collection stands”section above, this item should be
considered.)
[18]
- Collection from areas/trees free from pests
[19]
- (For masting species) Collecting in years of massive seed yield (mast years) which leads to minimum attack and
damage by insect pests and other predators thereby resulting in the collection of good quality seeds
[20]
- As much as possible, collecting seeds from top of trees before they fall to the forest floor
[21]
- Where it is impossible to harvest seeds/fruits from trees, collection mats or tarpaulins may be spread under trees
to catch falling fruits and seeds picked with minimum delay
[22]
- Collection of physiologically matured seeds at the “green” stage instead of collecting at the fully brown stage (
thereby avoiding possible attack by pests during later). However, green fruits should be allowed to go brown under
some level of shade before putting in the sun, otherwise the fruit will dry too fast. Excessive heating of the green
fruits may damage the seeds within
[23]
2. Transport
[24]
Harvested seeds should be transported to the place of further processing such as cleaning, drying or permanently
storage, as soon as possible. Especially for recalcitrant seeds, it is essential that they are transported in a way to
avoid heating; e.g. use of net sacks, piling over cross(transported in open trucks in preference to closed vans) to
allow air flow between sacks.
[25]
Large seeds often may be damaged by shocks, so it should be carefully managed? during transport and handling.
[26]
Labelling (preferably inside the transport item and outside) should be done before transport. This is to help maintain
the identity of seed lots
[27]
3. Strict hygiene within seed depot:
[28]
When seeds arrive at their place for pre-treatment or storage, they should be unloaded and emptied from the
transport medium (sacks, boxes etc.) immediately. Especially recalcitrant seeds need careful handling during the
period of pre storage.
[29]
It is essential to avoid mixing seed lots at this stage and therefore reporting should be done precisely.
[30]
To avoid contaminations and developing of moulds, seed species which have been collected from the ground (e.g.
acorns) should be cleaned. This may be easily done by floating in water. Sound seeds will sink while plant debris
and insect damaged acorns will float.
[31]
The seeds of some tree species are enclosed by fleshy fruit which needs to be removed (e.g. by using a depulping
machine followed by floating in water).
[32]
In some cases grading is required as it is believed that small seeds may not be fully developed. Nevertheless it
should be kept in mind that size differences may due to different origins and that grading influences the genetic
diversity of the seed lot.
[33]
4. [Sampling for] phytosanitary inspection:
[34]
Sampling for phytosanitary inspection can be done before or after storage. Since most infestations with pests and
especially diseases cannot be visually detected, laboratory testing is recommended.
[35]
It is crucial that the test sample be as homogenous as possible and be representative of the lot (ISPM 31:2008).
Where seed lot is found to be heterogeneous, increased sampling intensity should be required as recommended
by the International Seed Testing Association (ISTA). While the investigation on insect infestation can easily be
done by cutting the seed, tests on fungal infection needs specific laboratory analysis and sometimes specific
methods based on the fungus to be tested.
[36]
Laboratory testing before storage gives an overview on the seed quality and may also relates to germination
capacity. Especially for recalcitrant seeds, where the storage period is limited, seed lots of low quality (e.g. high
fungal infection rate) should not be aimed for storage as the infection may also infect the remaining healthy seeds
because of the relatively high storage temperature.
International Plant Protection Convention
Page 3 of 8
2009-003 (Annex 2) (4.3)
Forest Tree Seeds (DRAFT Rev2)
[37]
Within international trade. laboratory testing after storage and prior to export is recommended in those cases where
either requirements of the importing country exist or the seed lot originates in an area with harmful pests (at this
stage primarily fungi) known to be also seed borne or seed transmitted. Those specialised fungi often survive pre
storage seed treatment and also the storage regime with low temperatures and dried seeds.
[38]
5. Seed Treatment
[39]
Seed treatment before storage has at least three aims:
[40]
- Eliminating superficially growing pests (e.g. by chemical dipping, hot water treatment)
[41]
- Eliminating seed borne internally growing pests (e.g. by hot water treatment)
[42]
- Breaking dormancy to increase germination capacity (e.g. by chemical treatment, cold/humid treatment =
stratification)
[43]
Chemical treatment before storage against pests should be limited to recalcitrant seeds to be stored at high moisture
levels, because the low storage temperature of orthodox seeds inhibits fungal and insect growth. In addition some
pesticides may have a negative effect on the viability of the stored seeds. In special cases based on special
equipment, a chemical treatment is done during storage of recalcitrant seeds such as acorns.
[44]
However, complete elimination of seed-borne pathogens by physical or chemical treatments is not possible. The
aim of those treatments is to reduce the infection rate to a threshold which is feasible for seed storage or to reduce
disease outbreaks to a commercially acceptable level.
[45]
Examples for seed treatments
[46]
Mechanical
Visual separation of
healthy / unhealthy
seeds
Chemical
Fumigation
Separation of infested
seeds based on different
weight
Cleaning seed lots from
other seeds such as
weeds.
Floating in water to
eliminate debris and
insect infested seeds
Thermonebulisation
Chemical dipping
Physical
Heat
treatment:
- hot air treatment
- hot water treatment
steam
treatment
- microwave treatment
Ionizing radiation (not in
use for forest tree seeds
currently)
Biological
Application of beneficial
bacteria
Application of antibiotics
Application
antagonistic fungi
of
[47]
6. Seed storage
[48]
Unlike agricultural seeds, a large proportion of tropical forest tree species produce recalcitrant (desiccation
sensitive) seeds, which are difficult to collect, process, store and transfer. Thus there is the need to determine the
storage methods for seed that reduce pest incidence.
[49]
Seeds with orthodox storage behaviour are dried to low moisture content (7- 9%). In general conifer seeds can be
dried with higher temperatures in contrast to broadleaved tree seeds because of their poorly known biology.
Therefore for broadleaved tree seeds of the northern hemisphere drying temperatures should not exceed 15 to
20°C, to avoid damage of the seeds which can cause higher susceptibility to fungal infections.
[50]
Packaging is carried out using sealed containers with the view of preventing moisture exchanges during transfer
thus inhibiting fungal and insect development. Double labelling of the storage containers (inside and outside is
recommended).
[51]
Specific problems arise in the case of recalcitrant species where there is the need to keep seeds at relatively high
moisture content. Seeds may be treated with recommended fungicides to prevent possible fungal infection.
Desiccation sensitive seeds (recalcitrant seeds) may be transferred by placing seeds in a heat sterilized moistened
medium (e.g. wood shavings) packed in a well-ventilated sack. Transfer should be fast to prevent seeds from
germinating during the journey.
Page 4 of 8
International Plant Protection Convention
Forest Tree Seeds (DRAFT Rev2)
2009-003 (Annex 2) (4.3)
[52]
Chemical treatment by fumigation or dusting with insecticides or fungicides has been used to prevent damage from
insects and diseases.
[53]
7. Additional information
[54]
7.1. Method of seed collection (collection from tree top or from forest floor)
[55]
Collection
method
Example for seed
species
advantage
Collection from top
of tree by tree
climbers
Wide range of
conifers, fruit trees,
(Triplochiton,
Terminalia,
Mansonia, Ceiba
from West Africa
Free of soil borne
contaminations;
harvest
before
complete ripening
is possible
Labour intensive
Collection
from
forest floor without
additional device
and by hand
Some broad leave
trees, some fruit
Selection
concerning quality
is possible
Contamination
with soil borne
organisms,
no
influence
of
ripeness situation;
labour intensive
Collection
from
forest floor using
nets
Some broad leave
trees, some fruit
Contamination
with soil borne
organisms
excluded
Collection
from
forest floor using
seed
collection
exhauster
Some broad leave
trees, e.g. acorns,
beech nuts, olives
fast
Collection
complete
forest
litter,
heavy
contamination,
mechanical
damage of seed
possible
Needs
cleaning
before
storage;
health
and
phytosanitary test
recommended;
method
not
recommended for
forest tree seeds
Collection
from
squirrel caches
Some
species
Fast big amounts
of cones possible
Contamination
with soil borne
organisms
health
and
phytosanitary test
recommended
before storage
conifer
disadvantage
Remark
Need to invest in
training climbers
and
purchasing
tree
climbing
equipment
Needs
cleaning
before
storage;
health
and
phytosanitary test
recommended
Needs
cleaning
before storage;
[56]
7.2. Any special treatment applied to seeds.
[57]
7.3. Any recommended pre-sowing treatment for the seed lot.
[58]
7. 4. Seed quality test results documents
[59]
Forest tree seed quality tests contain the following analysis according to ISTA. Specific description for the individual
seed species may be obtained from ISTA
[60]
-
Purity analysis
[61]
-
1000 seed weight
[62]
-
Determination of moisture content
[63]
-
Viability testing (cutting test, X-Ray, tetrazolium test, indigo-carmine test)
[64]
-
Germination test (differentiate between germination capacity and seedling emergence test)
International Plant Protection Convention
Page 5 of 8
2009-003 (Annex 2) (4.3)
Forest Tree Seeds (DRAFT Rev2)
[65]
7. 5. Seed storage documents.
[66]
6.6. Seed source documents: These documents contain information on the name of the species (botanical and
local names), and geographical location of the seed source (elevation, temperatures, rainfall, soil types).
[67]
See ISTA documents
[68]
APPENDIX 1 - USEFUL REFERENCES
[69]
The references included in this Appendix are easily accessible and generally recognized as authoritative. The list
is neither comprehensive nor static.
[70]
Seed as a pathway, and seed-borne and seed-transmitted diseases
[71]
Agarwal, V.K.; Sinclair, J.B. 1996: Principles of Seed Pathology, 2nd ed. Lewis Publishers Ney York.539p
[72]
Cram, M.M. & Fraedrich, S.W. Seed diseases and seedborne pathogens of North America (forest trees). Tree
Planters’ Notes, 53(2): 35–44. Available at http://naldc.nal.usda.gov/download/41643/PDF
[73]
Johansen, E., Edwards, M.C & Hampton, R.O. 1994. Seed transmission of viruses: Current perspectives. Annual
Review
of
Phytopathology,
32:
363–386.
Available
at
http://www.annualreviews.org/doi/pdf/10.1146/annurev.py.32.090194.002051
[74]
Malone, J,P.; Muskett, A.E. 1997: Seed-borne fungi. Description of 77 fungus species. 3rd edition. ISTA, Zürich:
191 p.
[75]
Maude, R.B. 1996: Seedborne Diseases and their control, Principles and Practice. CAB International: 280 p.
[76]
Mink, G.I. 1993. Pollen- and seed-transmitted viruses and viroids. Annual Review of Phytopathology, 31: 375–402.
Available at http://www.annualreviews.org/doi/pdf/10.1146/annurev.py.31.090193.002111
[77]
Mittal, R.K.; Anderson R.L.; Mather S.B. (1990): Microorganisms associated with tree seeds: World Checklist
1990. Information Report PI-X-96, Petawa National Forestry Institute, Forestry Canada, 25
[78]
Neergard, P. 1977: Seed Patholgy Volume I & II. MacMillan Press Ltd. London: 1187p.
[79]
Richardson, M.J. 1990. An annotated list of seed-borne diseases, 4th edn. Bassersdorf, Switzerland, International
Seed Testing Association (ISTA). Available at http://www.seedtest.org/en/productdetail---0--0--0--32.html
[80]
Note: Update of the International Seed Testing Association (ISTA) “List of seed-borne diseases” is in progress as
part of the TESTA project on the basis of a full literature review with expert analysis of scientific papers. It will take
the form of a database on the ISTA website (http://services.prismanet.ch/SeedDiseasesDb).
[81]
Rohmeder, E. 1972: Das Saatgut in der Forstwirtschaft. Paul Parey, Hamburg: 273 p.
[82]
Sastry, K.S. 2013. Seed-borne plant virus diseases. New Delhi, Springer Publishing.
[83]
Note: An International Seed Federation
(http://www.worldseed.org/isf/home.html).
[84]
Suszka, B.; Muller, C.; Bonnet-Masimbert, M. 1996: Seeds of forest broadleaves from harvest to sowing. INRA,
Paris: 294p
[85]
Seed testing and sampling protocols
[86]
Agarwal, P.C., Mortensen, C.N. & Mathur, S.B. 1989. Seed-borne diseases and seed health testing of rice.
Copenhagen, Danish Government Institute of Seed Pathology for Developing Countries and Kew, CAB International
Mycological Institute.
[87]
Albrechtsen, S.E. 2005. Testing methods for seed-transmitted viruses: Principles and protocols. Oxford, UK,
Oxford University Press.
[88]
CABI (CAB International). 2006. Testing methods for seed-transmitted viruses: Principles and protocols.
Wallingford, UK, CABI Publishing.
[89]
Chahal, S.S., Thakur, R.P. & Mathur, S.B. 1994. Seed-borne diseases and seed health testing of pearl millet.
Copenhagen, Danish Government Institute of Seed Pathology for Developing Countries.
Page 6 of 8
(ISF)
pest
list
is
available
on
the
ISF
website
International Plant Protection Convention
Forest Tree Seeds (DRAFT Rev2)
2009-003 (Annex 2) (4.3)
[90]
EPPO (European and Mediterranean Plant Protection Organization). Diagnostic protocols for regulated pests.
Paris, EPPO. Available at http://archives.eppo.int/EPPOStandards/diagnostics.htm (accessed December 2013).
[91]
ISHI (International Seed Health Initiative). Manual of seed health testing methods. Nyon, Switzerland, International
Seed Federation (ISF). Available at http://www.worldseed.org/isf/ishi_vegetable.html (accessed July 2013).
[92]
ISTA (International Seed Testing Association). 2012. International rules for seed testing. Seed health testing
methods. Bassersdorf, Switzerland, ISTA. Available at http://www.seedtest.org/en/download-ista-seed-healthtesting-methods-_content---1--1132--746.html
International Plant Protection Convention
Page 7 of 8
APPENDIX 2 - GENERAL CLASSIFICATION OF SEED TREATMENTS
[93]
[94]
Pesticides:
[95]
Generally used against fungi and insect pests and occasionally against bacteria and nematodes. The use of
pesticides as seed treatment is regulated by national legislation and therefore authorization, formulations and
concentration differ among countries and may also change over time.
[96]
Disinfectants:
[97]
Generally used against bacteria and viruses. Disinfection may take place during various steps in seed processing
(e.g. seed extraction, seed priming 2or during a dedicated disinfection process. Seed disinfection can eradicate or
inactivate micro-organism infestation and infection, depending on the process and the biocide applied.
[98]
Physical treatments:
[99]
Dry heat, steam, hot water, irradiation, (ultraviolet) light, high pressure, deep-freezing and other physical
treatments are used to control bacteria, viruses, fungi and nematodes.
[100] Biological treatments:
[101] These are based on different modes of action, such as antagonism, competition and induced resistance. The pest
may actually be on the seed at the time of planting but establishment is not possible or strongly reduced when the
biological treatment is activated during germination. Biological treatments may also be used against soil-borne
pests (e.g. nematodes) to create a “pest free zone” around the germinating seed and the root zone of the plant.
[102] Footnote 1: Seeds are defined as “A commodity class for seeds for planting or intended for planting and not for
consumption or processing” (ISPM 5).
[103] Footnote 2: Seed priming: Pre-treatment of seeds by various methods in order to improve the seed germination
rate, the percentage of germination and the uniformity of seedling emergence.
International Plant Protection Convention
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