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Phytosanitary Measures for Seeds - nappo

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<strong>Phytosanitary</strong> <strong>Measures</strong> <strong>for</strong><br />

<strong>Seeds</strong><br />

Field Inspections<br />

Seed Testing<br />

Seed Treatments


Seed Industry Perspective on<br />

<strong>Phytosanitary</strong><br />

• Presence of any pest reduces seed quality<br />

• Seed Companies have designed and<br />

implemented QM programs to reduce<br />

exposure to, and eliminate seed pests<br />

throughout production life cycle<br />

• ASTA Guide to Seed Quality Management<br />

Practices<br />

• Federal Seed Act<br />

• OECD Seed Schemes


Seed Industry Perspective on<br />

<strong>Phytosanitary</strong><br />

• The seed industry employs the same<br />

methods as the NPPOs require to<br />

manage, monitor, and ensure seed quality<br />

• <strong>Phytosanitary</strong> field inspections<br />

• Seed testing <strong>for</strong> pests<br />

• Seed treatments<br />

• Front line method <strong>for</strong> industry:<br />

phytosanitary field inspection


<strong>Phytosanitary</strong> Field<br />

Inspections<br />

• Companies conduct their own<br />

inspections <strong>for</strong> many pests<br />

Monitor pathogen races<br />

e.g: Exserohilum turcicum


Agricultural Industry:<br />

Pests Data Collection<br />

<strong>Phytosanitary</strong> Field Inspections<br />

To document the<br />

absence of a quarantine<br />

pest is just as important<br />

as recording their<br />

presence.<br />

Several ASTA member companies are<br />

accredited <strong>for</strong> <strong>Phytosanitary</strong> Field Inspection<br />

under USDA-APHIS-PPQ-National Seed Health<br />

System


<strong>Phytosanitary</strong> Field Inspections<br />

(NSHS)<br />

• Establish the seed field inspection pattern<br />

• 1. The seed field inspection pattern should<br />

ensure that all parts of the field are adequately<br />

and proportionately represented in the plants<br />

inspected within the various usual microclimates<br />

of the field.<br />

• 2. As long as these requirements are met, the<br />

pattern of field inspection can vary.


<strong>Phytosanitary</strong> Field Inspections<br />

(NSHS)<br />

• Stagger “X” pattern: used <strong>for</strong> cereal<br />

crops<br />

• Equidistant passes pattern: used <strong>for</strong><br />

crops other than cereals<br />

• Design <strong>for</strong> field inspections: determine the<br />

minimum number of field passes in<br />

relation to field size to give a minimum of<br />

95% confidence level in detecting an<br />

infection level of 0.1%.


Table 1. Minimum field passes per acre.<br />

Field size (acres) Minimum # passes<br />

0 - 1 6<br />

1 - 5 9<br />

5 - 10 11<br />

10 - 20 13<br />

20 - 50 17<br />

50 - 100 20<br />

100 - 200 24<br />

200 - 500 30<br />

500 – 1000 36<br />

1000 + 42


Advantages of Field<br />

Inspections<br />

• Allows a large number of plants to be<br />

inspected (one plant can represent<br />

thousands of seeds)<br />

• Plants exhibiting symptoms are tested to<br />

confirm<br />

• Infected plants/fields are removed;<br />

potentially infected seeds don’t enter<br />

channels of trade


Advantages of Field Inspection<br />

• Identification of special areas or microclimates<br />

in the field that appear different<br />

enough to warrant special attention when<br />

inspected. These would include:<br />

• Rivers and streams<br />

• Drainage areas<br />

• Low spots<br />

• Weedy areas


Advantages of Field Inspection<br />

• Areas of the field affected by borders,<br />

such as:<br />

• Field edges<br />

• Tree lines in the field<br />

• Adjacent fields of a similar crop<br />

• Presence of buildings or bins


Advantages of Field Inspection<br />

• Drought stress areas, such as:<br />

• High spots<br />

• Light textured soils<br />

• Margins or overhead irrigation areas


<strong>Phytosanitary</strong> Seed Testing<br />

• Should only be used <strong>for</strong> pests/pathogens<br />

<strong>for</strong> which seed is known to be a pathway<br />

• Often used when a phytosanitary field<br />

inspection was not conducted (some<br />

NPPOs require field inspection plus a<br />

seed test)<br />

• Often used to monitor/verify effectiveness<br />

of an import program


<strong>Phytosanitary</strong> Seed Testing<br />

Issues<br />

• Use of “official” methods: system works<br />

best when NPPOs of both exporting and<br />

importing countries use the same method<br />

• Problems occur when different test<br />

methods are used <strong>for</strong> the same<br />

pest/pathogen<br />

• Problems can occur when regulatory<br />

decisions are based on protein or DNA<br />

based methods


<strong>Phytosanitary</strong> Seed testing<br />

Issues<br />

• Accuracy based on accuracy of the seed sample: is the<br />

sample representative of the seed lot<br />

• Need to use official seed sampling methods; e.g.,<br />

AOSCA<br />

• Accuracy based on sensitivity of method<br />

• Protein and DNA based PCR tests assume correct<br />

primers are used<br />

• Primers often react to other strains or even species of<br />

pest/pathogen, producing false positives


<strong>Phytosanitary</strong> Seed Testing<br />

Issues<br />

• Protein and DNA based methods do not<br />

necessarily mean the pest/pathogen is<br />

viable!<br />

• Biological test methods (blotter tests, agar<br />

assays, etc.) provide the most definitive<br />

results, but can be time consuming<br />

• Viruses: usually show symptoms (field<br />

inspection), but require protein or DNA<br />

based test methods


Seed Treatments<br />

• Many countries accept seed treatments <strong>for</strong><br />

mitigating pests of phytosanitary concern<br />

• Often when field inspections were not<br />

per<strong>for</strong>med <strong>for</strong> the pest of concern (e.g. reexport)<br />

• Sometimes can be per<strong>for</strong>med at port of entry<br />

• Sometimes issues with registrations and<br />

dosages of the active ingredient


Seed Treatments<br />

• Emerging technologies offer promise<br />

• Good opportunities <strong>for</strong> harmonization<br />

among countries<br />

• Issues with organic seed


Summary<br />

• <strong>Phytosanitary</strong> field inspections offer significant<br />

protection against seed pests by preventing<br />

pests from getting into channels of trade<br />

• Seed tests <strong>for</strong> phytosanitary purposes work best<br />

when NPPOs use the same methods<br />

• Both seed testing and treatments are viable<br />

substitutes <strong>for</strong> field inspection when field<br />

inspection is not possible.


Thank You!<br />

rdunkle@amseed.org

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