SWEET POTATO (Ipomoea batatas) (L.) Schott.

I. Application and Amplification of General Seed Certification Standards

A. The General Seed Certification Standards are basic and, together with the following specific standards 

     constitute the standards for certification of sweet potato.

B. The General Standards are amplified as follows to apply specifically to sweet potato.

         All certified classes shall be produced either from vine cuttings or from sprouts cut from the bed whose source and 

identity may be assured and approved by the Certification Agency.

II. Land requirements

     (a) Land to be used for seed production of sweet potatoes  shall be free of volunteer plants.

    (b) Avoid sweet potato residue and drainage from other sweet potato fields.

III. Field Inspection

        A minimum of two inspections shall be made as follows;

        1. the first inspection of plant bed shall be made when plants are large enough to transplant;

        2. the second inspection shall be made shortly after transplanting in the seed field.

IV. Field Standards

A. General requirements

1. Isolation

        Seed fields shall be isolated from the contaminants shown in the column1of the Table below

 by the distances specified in columns 2 and 3 of the said Table:

        Contaminants                                                                                   Minimum distance (meters)

                                                                                                                Foundation        Certified

            1                                                                                                         2                     3

Fields of other varieties                                                                                   5                      5 

Fields of the same variety not conforming to 

varietal purity requirements for certification                                                      5                      5 

B. Specific requirements

        Factor                                                                                              Maximum permitted (%)*

                                                                                                                Foundation            Certified

       Plant bed

            Plant infected by:

            Black rot (Ceratostomella fimbriata 

            (Ell.& Halst.) J.A. Elliot)                                                                None                    None

            Wilt (Fusarium oxysporum f. batatas 

            (Wr.) suyder &Hanson)                                                                 None                    None

            Scurf (Monilochaetes infuscans (Ell.& Halst.) Ex.Harter)                None                    None

            Offtypes                                                                                        None                    None

       Seed field     

            Plants infected by:

            Wilt (Fuasrium oxysporum f. batatas 

            (Wr.) Snyder& Hanson                                                                None                     None

            Mosaic                                                                                         0.050                    0.10

            Offtypes                                                                                        0.10                     0.20

* Maximum permitted at each inspection.  

   Note: All offtypes and disease plants should be rogued out alongwith roots.                                                       

V. Seed  Standards

       1. The seed material shall be reasonably clean, healthy and firm and shall conform to the varietal characteristics of the

           variety.  The roots not conforming to varietal characteristics shall not exceed 0.10% and 0.20% (by number) for

           Foundation and Certified seed classes respectively.

      2. Cut, bruised, unshapy,  cracked roots or  those damaged by insects (except sweet potato weevil), slugs or worms

          shall not exceed more than 2.0% (by weight).

      3. Maximum tolerance limit of roots showing visible symptoms caused by the diseases, sweet potato weevil and other

          factors will be as follows:

                                                                                                               Maximum permissible limits   

                        Diseases

                                                                                                 Foundation                         Certified

    Storage rot                                                                              None                                None

     Black rot (Ceratostomella fimbriata

    (Ell.& Halst.) J.A. Elliot)                                                          None                                None

    Wilt (Fusarium oxysporum f. batatas

    (Wr.) suyder &Hanson)                                                           None                               None

    *Scurf (Monilochaetes infuscans (Ell.& Halst.) Ex.Harter)         None                               None

    Wilt (Fuasrium oxysporum f. batatas

     (Wr.) Snyder& Hanson                                                          None                               None

    Internal cork                                                                            5.0%                              5.0%

    Nematode                                                                               None                              None

    Wire worm                                                                              1.0%                              1.0%

    Other distinguishable                                                                0.10%                            0.20%

    Sweet potato weevil (Cylas formicaris Fab.)                            None                              None 

* A root carrying 10.0% or above scurfed surface would be considered as one infected unit.