Planting materials from Philippines into Ghana. A qualitative Pest Risk Analysis




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Assessing the Risk of Importation of Vanilla (Vanilla tahitensis and V. fragrans) planting materials from Philippines into Ghana.
A Qualitative Pest Risk Analysis

(DRAFT)

Agency contact:

Eunice Adams (Mrs.)

Plant Protection and Regulatory Services Directorate

Ministry of Food and Agriculture

P.O.Box M37

Accra
October 6, 2005


Executive Summary

This document assesses the risk associated with the Importation of Vanilla (Vanilla tahitensis and V. fragrans) planting materials from Philippines into Ghana.

Information gathered revealed that the following sap transmissible viruses could be introduced into Ghana with the importation of the planting materials:

Cymbidium mosaic virus



Odontoglossum ringspot virus

Cucumber mosaic virus

Vanilla mosaic virus

Vanilla necrosis potyvirus

Uncharacterized potyviruses

Uncharacterized rhabodvirus-like particles
All these pests adversely affect vanilla production and risk of introduction in planting material is high.
The Pest Risk Analysis (PRA) which was initiated by a pathway (a request made to import the commodity for a commercial business enterprise) and is based on the International Standards for Phytosanitary Measures Guidelines for Pest Risk Analysis i.e. ISPM 2 (FAO 1996)..

Risk management options are based on general and technical recommendations that provide the necessary precautions to avoid accidental movement of pests.


1.0 Introduction:

This Pest Risk Analysis (PRA) draft document was prepared for an entrepreneur who is receiving support from the Market Oriented Agriculture Programme of the German Technical Cooperation (GTZ) in Ghana by the Plant Protection and Regulatory services Directorate of the Ministry of Food and Agriculture. It initiated by a request made to import vanilla planting materials (not seeds) for a commercial business enterprise to be set up in the Western Region of Ghana. The importation of planting materials pose a risk of introduction of viruses which are of quarantine concerns to Ghana.


The PRA is based on the “International Standards for Phytosanitary Measures: Guidelines for Pest Risk Analysis” (ISPM 2). A Pest Risk Assessment was conducted to determine whether a pest is a quarantine pest and evaluates its introduction potential. Pest Risk Management options have been identified to facilitate. the decision making process of reducing the risk of introduction of a quarantine pest (FAO, 1996). The PRA therefore consists of three stages; initiating the process for analyzing the risk, assessing pest risk and managing pest risk.
2.0 Risk Assessment

    1. Stage1: Initiation of the PRA Process

This process was initiated by the fact that the importation of vanilla planting materials such as cuttings, rooted plant materials and untested invitro plantlets allow the introduction and /or spread of quarantine pests.
A general list of pests of Vanilla tahitensis and V. fragrans vanilla that are likely to follow the pathway (i.e. be carried by the commodity) was generated from databases and literature sources (Appendix 1).
The seven potential quarantine pests (i.e. pests of potential economic importance to the area endangered thereby and not yet present there) are likely to be introduced with the vegetative propagating materials (cuttings). These are listed in the Table 2 below:

Table 2 : Potential quarantine pests of Vanilla tahitensis and V. fragrans (Vanilla)

Cymbidium mosaic virus


Odontoglossum ringspot virus

Cucumber mosaic virus

Vanilla mosaic virus

Vanilla necrosis potyvirus

Uncharacterized potyviruses

Uncharacterized rhabodvirus-like particles

2.2 Review of earlier PRAs
Neither the pathway nor any of the pests listed above have been subjected to a PRA process in Ghana. A search on Internet did not also produce any previous PRA.
2.3 Conclusion of Stage 1
The above listed viruses are known to be associated with vanilla planting materials. They have adversely affected vanilla production in several producing countries in the South Pacific Ocean. (Farreyrol et al, 2000).
Although there is no uncertainty of uncharacterized potyviruses and rhabodvirus-like particles being of quarantine concern, their mode of transmission of the is not known (Pearson et al 1991), The PRA of these uncharacterized viruses stops at this stage since there is no information on their biology and economic importance. Expert judgment is required to assess the establishment, spread and economic importance potential in Ghana (FAO, 1996).
2.4 Stage 2: Pest Risk Assessment
The quarantine pests listed in table 2 were subjected to further analysis. The PRA was conducted without prior information on agronomic practices and the pests and diseases that associated with the crop in the Philippines.

Comments on Quarantine Pests



Cymbidium mosaic virus
This virus is absent in Africa. The major hosts belong to the species in the order Orchidaceae, which are mainly ornamentals. Although the virus is borne internally; symptoms are visible to the naked eye on plant parts such as leaves, bulbs/tubers/corms/rhizomes, seedlings and micro propagated plants. Infected roots, flowers/inflorescences and fruits are symtomless (CABI, 2004).

Cymbidium mosaic virus has no known vector. Transmission is by mechanical inoculation, contact between plants and through pollen in some species. It can also be spread in nutrient solutions used in irrigation systems. The virus is not seed-transmitted (CABI, 2004).


Odontoglossum ringspot virus
Odontoglossum ringspot virus has been reported in South Africa. It is spread by mechanical wound inoculation (by the use of contaminated cutting tools).and can be readily transmitted to hydroponically-grown plants if the circulating nutrient fluid in which plants are grown is contaminated. It may also be transmitted by contaminated pollen, It affects than 20 species in the order Orchidaceae. No vector is known to transmit the virus (CABI, 2004).

Vanilla Mosaic Virus

The major host of Vanilla Mosaic Virus is Vanilla planifolia (vanilla) The virus is introduced into new vanilla plantings through the use of virus-infected vegetative cuttings. It is spread mechanically through pruning tools. Insect vectors belonging to the Aphididae transmit the virus in a non-persistent manner. The virus has been transmitted from V. tahitensis to V. pompona by the aphid Myzus persicae under experimental conditions(CABI,2004). Symptoms of Vanilla Mosaic Virus infection are leaf mosaic and malformation, distortion of vines and shoot tip dieback. (CABI, 2004).


Cucumber mosaic virus


Cucumber mosaic virus has a wide host range and infects more than 800 species of both monocotyledonous and dicotyledonous plants from over 85 families. They include members of the Cucurbitaceae, Solanaceae and Araceae families. The primary hosts are Capsicum annuum, Cucumis sativus, Dioscorea and Lycopersicon esculentum. There are also some minor hosts such as Coriandrum sativum (coriander), Luffa aegyptiaca (loofah), Spinacia oleracea (spinach), Tetragonia tetragonioides (Newzealand spinach), Vigna unguiculata (cowpea) and Vitis vinifera (grapevine). Cucumber mosaic virus infects many weeds that can act as virus reservoirs and infect crops in adjacent fields. They include wild hosts such as Amaranthus caudatus (garden amaranth), Antirrhinum majus (snapdragon), Atriplex hortensis (garden orache) and Calendula officinalis (Pot marigold) (CABI, 2004).
The virus which was previously not reported in Vanilla tahitensis and V. fragrans (vanilla), causes a severe disease of the crop in French Polynesia and a Reunion Island ( Farreyrol et al 2000).

Control measures for Cucumber mosaic virus are mainly preventive since conventional methods of virus control are difficult to apply due to the wide host range (CABI, 2004).


Vanilla necrosis potyvirus

The major host is Vanilla planifolia (vanilla) however it can be mechanically transmitted from naturally infected vanilla (Vanilla planifolia) to Nicotiana benthamiana and from N. benthamiana to N. clevelandii, Chenopodium amaranticolor, C. quinoa, Citrullus lanatus, Cucurbita pepo and Pisum sativum experimentally (CABI, 2004).


The virus is introduced into new vanilla plantings through the use of virus-infected vegetative cuttings for propagation. It is spread by mechanical transmission via pruning tools. Insect vectors belonging to the Aphididae also transmit the virus. Under experimental conditions, the virus is transmitted from infected to healthy Nicotiana clevelandii plants by Aphis gossypii and Myzus persicae in a non-persistent manner. (CABI, 2004).
Stage 2 examines whether the criteria for a quarantine pest status are satisfied based on the geographical distribution, biology and economic importance (FAO, 1996). The potential for introduction of these viruses is assessed based upon information obtained from databases and the Internet.
Since Cymbidium mosaic virus, Odontoglossum ringspot virus, Cucumber mosaic virus, Vanilla mosaic virus and Vanilla necrosis potyvirus are all sap- transmissible, the risk assessment would be considered as one.
2.4.1 Geographic and Regulatory Criteria

There is no record on the cultivation of vanilla in Ghana. Apart from Cucumber Mosaic virus the other four virus have not been recorded in Ghana (CABI, 2004, Oduro, 2000). Its distribution has not been assessed however crops affected by this virus are officially controlled in Ghana. Cucumber Mosaic virus is of quarantine concern because a recent report of causing a severe disease of vanilla.( Farreyrol et al 2000) .



2.4.2 Economic importance criteria


This is an expression of the risk of the pest having entered, becoming established and spreading in Ghana. The factors under consideration are establishment potential; spread potential after establishment, potential economic importance and introduction potential.
2.4.2.1 Establishment Potential

The Rain / Decidous forest agro-ecological zones in Ghana (with mean annual rainfall of 2,200 mm and annual average temperature ranging between 26.1°C and 28.9°C). The ecological factors in the PRA area would therefore support the growth and establishment of Vanilla which thrives best in warm, moist climates without pronounced dry season with temperatures ranging between 21-32°C and a mean of 26°C (CABI, 2004). The crop requires an evenly distributed annual rainfall of up to 2000-2500 mm/ and of 2 months drier period flowering (CABI, 2004).

These sap- transmissible viruses are introduced and spread in cuttings used for propagation (Pearson et al 1991). Once introduced, the likelihood of establishment of viral infections in vanilla plantings is high due to favorable climatic factors.
2.4.2.2 Spread potential after establishment.

The viruses are spread mechanically through pruning tools. Natural transmission of the Vanilla Mosaic virus does occur through insect vectors belonging to the family Aphididae. These vectors are common in Ghana. Thus the establishment and spreading of this viral disease in Ghana is very high due to the presence of insect vectors and certain crop husbandry practices such as pruning.


Although the initial request is to import a quantity of planting materials to establish one-hectare farm, requirement of planting materials is likely to increase with the growth of the industry. The likelihood of spread of viral infections would be high due to the informally way of sourcing planting materials by Ghanaian Farmers.

2.4.2.3 Potential economic importance

There is no evidence of spread of Vanilla Mosaic Virus in V. tahitensis in French Polynesia and Cook Islands and in V. planifolia in Fiji and Vanuatu. Symptoms of the virus on individual plants appear severe however disease incidence is low and the economic impact of the disease appears slight (CABI, 2004).

Cymbidium mosaic virus and Odontoglossum ringspot virus infection lead to, reduction in plant growth and quality (CABI, 2004).


Cucumber Mosaic virus has the widest host range of any virus and is one of the most damaging viruses of temperate agricultural crops worldwide. It is also a major virus in the tropics. The Risk Criteria for economic importance of the virus is high (CABI, 2004).
Vanilla Necrosis potyvirus is currently the most serious disease of vanilla in the South Pacific region. Infected plants die within 3-12 months of the first symptoms. The disease can have a major effect on production (CABI, 2004).
The control measures are mainly based on cultural practices such as cleaning and sterilization of pruning implements to o reduce the chances of mechanical transmission, weed control (alternate host) to reduce potential aphid vector populations. The adoption of these stringent cultural practices would increase labour cost.
The use of insecticides to control insect vectors is not recommended(CABI, 2004).
2.4.2.4 Introduction potential

The documented pathways for introduction the virus in international trade include seedlings/micro propagated plants and stems i.e. (above ground)/shoots/trunks/branches) (CABI, 2004).

These are the major propagating materials needed in the establishment. of the crop. The virus is borne internally and is invisible.(CPC, 2004) and would not be detected through visual post entry Phytosanitary inspection conducted on arrival into Ghana.
The introduction potential of these viruses in the absence of other mitigations is high.

2.4.2.5 Conclusion of Stage 2 of PRA


These viral infections of vanilla satisfy the definition of quarantine pests. Importation of stem cuttings and or micro propagated planting materials poses sufficient risk to warrant mitigation.(Farreyrol et al, 2000).

Virus infections are a limiting factor in the successful cultivation of vanilla. They reduce the lifetime of the vines; inhibit the flowering leading to reduction in the production of vanilla beans. Severe infections lead to the death of the vines (Pearson et al. 1991, Farreyrol et al, 2000).


3.0 Stage 3: Pest Risk management
The movement of cuttings of vanilla involves the risk of accidental introduction of sap-transmissible viruses that spread through cuttings used for propagation. There is therefore the need to adopt effective mitigation procedures to ensure that the consignment of vegetative material is substantially free from these viral infections that are of quarantine concern.

3.1 Risk management options

Pearson et al; 1991 have provided the general and technical recommendations for the importation of vanilla germplasm which could be adopted for the importation of the planting materials. These guidelines are summarized below would be adopted to ensure that planting materials imported into Ghana are substantially free from viral infections:

  • The transfer of germplasm should be carefully planned in conjunction with the National Plant Quarantine authorities in the Philippines. The material should be accompanied by the necessary Phytosanitary documents and be in quantities that allow satisfactory examination.

  • Germplasm should not be moved as rooted plant material but should be moved as seed, in vitro pathogen-tested plantlets, or as cuttings re-established from pathogen-tested in vitro plantlets grown under containment.

  • All germplasm should be collected from healthy-looking plants , (preferably maintained

in a glasshouse or other enclosure, to reduce the microbial contamination present on field-grown plants).Where possible, germplasm should be obtained from areas where pathogens of quarantine concern are not known to occur.

  • All germplasm should be tested for the presence of viruses either in the country of origin, in an intermediate quarantine center, or under confinement in Ghana. Intermediate and post-entry quarantine is required if it is necessary to import untested germplasm, and plants should be tested for the presence of viruses. Since some vanilla viruses may occur at low levels in- vitro cultures, both the original plantlet and the first generation of subcultures should be tested.


  • On arrival into Ghana, in vitro plantelets should be examined for microbial contamination, and if they are absent, plantlets should be grown under containment with regular inspection for six months.

The risk of accidental introduction of non-viral pests is avoided through good tissue culture practices (Pearson et al 1991).


Conclusion for Stage 3

The above guidelines that ensure the Phytosanitary safety of vanilla gemplasm in international trade can be adopted in the importation of the vanilla planting materials from the Philippines. There is the need to monitor for effective implementation of the above mitigation options to safeguard the vanilla crop to be introduced into the Ghana.



Appendix 1

Table 1: Pest Categorization - Identification of Pests of Vanilla tahitensis and V. fragrans (vanilla) cuttings


PATHOGENS



















FUNGI


Scientific Name, Classification

Distribution


Plant Part Affected


Quarantine Pest

Follow Pathway


Comments

References


Scientific name,auth., life stages, taxo.ordr/family

Country




Y or N

Y or N




CABI 2004

Fusarium oxysporum f.sp. vanillae ( Ascomycetes,

Hypocreales)



Indonisia

R

N

N




CABI 2004

Glomerella vanillae

widespread


L S

N

N




CABI 2004

Nectria vanillae

widespread


L S

N

N




CABI 2004

Phytophthora

widespread


L S










CABI 2004

Corticium rolfsii Curzi [teleomorph]

(Polyporales, Corticiaceae)



Gh

R

N

N




CABI 2004

Uromyces joffrini,

(Uredinales, Pucciniaceae)

widespread


L

N

N




CABI 2004


Cont Table 1

PATHOGENS



















BACTERIA


Scientific Name, Classification

Distribution

Subtraction

Rule

Plant Part Affected


Quarantine Pest

Follow Pathway


Comments

References


Scientific name,auth., life stages, taxo.ordr/family







Y or N

Y or N







Acidovorax avenae subsp. cattleyae (Pavarino 1911) Willems et al. 1992 Burkholderiales

Comamonadaceae



PH

Wp

N

N




CABI 2004


Cont Table 1




VIRUS

Scientific Name, Classification

Distribution


Plant Part Affected


Quarantine Pest

Follow Pathway


Comments

References


Cymbidium mosaic virus,

Worldwide


Wp

Y

Y

usually symptomless;

occasionally mild mottles or mild chlorotic streaks are observed on leaves
sap-transmissible
spread through cuttings


Farreyrol et al 2000

CPC, 2004 CABI 2004

Odontoglossum ringspot virus,

widespread




Wp

Y

Y

usually symptomless;

occassionally mild mottles are observed on the leaves of Vanilla fragrans and

V. tahitensis.
sap-transmissible
Spread through cuttings.


Farreyrol et al 2000

Pearson et al 1991




Cont Table 1




Cont. VIRUS

Scientific Name, Classification

Distribution


Plant Part Affected


Quarantine Pest

Follow Pathway


Comments

References


Cucumber mosaic virus

South Pacific islands, Indian Ocean Islands

Gh

WP

Y

Y

Recent discovery. Causes severe stunting of Vanilla tahitensis and V. fragrans

Farreyrol , et al 2000

Pearson et al 1991


Vanilla mosaic virus

FP,CI, FJ, Va

L, S, Wp

Y

Y

sap-transmissible and is also spread in cuttings used for propagation.


Farreyrol , et al 2000

Pearson et al 1991



Vanilla necrosis potyvirus
Watermelon mosaic potyvirus-II Wang et al. (1993)

FI,TO, VA

L, S, Wp

Y

Y


sap-transmissible and is also spread in cuttings used for propagation.

Farreyrol , et al 2000

Pearson et al 1991


Uncharacterized potyviruses


FI, VA

L, S, Wp

Y

Y

Mode of transmissible is not known

Farreyrol , et al 200 Pearson et al 1991


Uncharacterized rhabodvirus-like particles


FI, VA

L, S, Wp

Y

Y

Mode of transmissible is not known

Farreyrol , et al 2000

Pearson et al 1991




Cont Table 1






ARTHROPODA / GASTROPLODES































Scientific Name, Classification

Distribution


Plant Part Affected


Quarantine Pest

Follow Pathway


Comments

References

















Y or N

Y or N













Amsacta transiens Wlk Lepidoptera

, Arctiidae

PH

Wp

N

N




CABI 2004







Nematoda


























Helicotylenchus dihystera (Cobb, 1893) Sher, 1961

Nematoda, Hoplolaimidae



widespread

R, L, V, WP

N

Y

Eggs, juveniles, adults likely to be carried on seedlings/micro propagated plants; borne externally; visible under light microscope

CABI 2004







Pratylenchus brachyurus (Godfrey, 1929) Filipjev & Schuurmans Stekhoven, 1 Nematoda

, Pratylenchidae 941,




widely distributed

R

N

N




CABI 2004








Legend

Geographic Distribution: Fiji (FI), Philippines (PH), Tonga (TO), Vanuatu (VA) Cook Island (CI) French Polynesia( FP) as they are specifically listed in the references.


Plant Parts: Se= seed, F = fruit, In - inflorescence, L = leaves, R = roots, S = stem, Wp = whole plant

Quarantine Pest and Follow Pathway: Y = yes; N = no

Highlighted rows indicate pests that will follow the pathway and are quarantine pests.


References:

CABI, 2004; Crop Protection Compendium (2004 edition) CAB International, Wallington, UK


FAO 1996, International Standards for Phytosanitary Measures Guidelines for Pest Risk Analysis i.e. ISPM 2

Farreyrol K, Pearson MN, Grisoni M and Leclercq-Le Quillec F, 2000: Severe stunting of Vanilla tahitensis in French Polynesia caused by Cucumber mosaic virus (CMV), and the detection of the virus in V. fragrans in Reunion Island. New Disease Reports on-line [http://www.bspp.org.uk/ndr/] vol.2 Last assessed 10/12/2005

Farreyrol, K, Grisoni, M, Leclercq-Le Quillec, F and Pearson, MN , Characterisation of vanilla viruses and development of testing procedures. http://www.usc.edu/extrelations/news_service/apruwww/StudentPapers/FinishedPapers/FarreyrolPaper.html Last assessed 10/12/2005



Oduro K. A, 1998, Checklist of plant diseases in Ghana. Ministry of Food and Agriculture- Plant Protection and Regulatory Services Directorate. Accra, Ghana. Pp105
Pearson M.N, Jackson G.V.H., Zettler, F.W. and. Frison E.A (Eds); 1991 FAO/IBPGR Technical guidelines for the safe movement of vanilla germplasm. Food and Agriculture Organization / International Board for Of the United Nations Plant Genetic Resources. www.ipgri.cgiar.org/publications/pdf/296.pdf



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