100 likes | 178 Views
Distribution of Healthy Propagules - NCRPIS program. NPGS Curator Workshop 2005 Chicago Charles C. Block, Ph.D. Plant Pathologist. Three disease examples. Stewart’s wilt of corn – Pantoea ( Erwinia ) stewartii Sunflower downy mildew – Plasmopara halstedii
E N D
Distribution of Healthy Propagules- NCRPIS program NPGS Curator Workshop2005 Chicago Charles C. Block, Ph.D. Plant Pathologist
Three disease examples • Stewart’s wilt of corn – Pantoea (Erwinia) stewartii • Sunflower downy mildew – Plasmopara halstedii • Squash mosaic virus of cucurbits
Stewart’s wilt disease management • This is the top phytosanitary issue for corn seed exports • Primary objective – to be able to certify seed as free of Erwiniastewartii. Field inspections document presence/absence of Stewart’s wilt.
Stewart’s wilt disease management • Absent in field – accession meets phytosanitary requirements for Stewart’s wilt. • Present in field – most countries accept lab testing in lieu of field data. We do this testing in-house. • About 90% of field positives are negative by ELISA.
Approximate cost per accession for Stewart’s wilt lab testing ELISA test kit $1.60 (4 wells/acc.) Buffers $0.02 Student labor $1.98 (15 min.) Tech. labor ~$1.25-1.65 (3-4 min.) ~Cost per accession $4.85 - 5.25 # Accessions tested: 1994 – 59 1995 – 82 1996 – 136 1997 – 134 1998 – 61 1999 – 141 2000 – 43 2001 – 152 2002 – 124 2003 – 182 2004 – 377 2005 – 442
Sunflower downy mildew disease management Objective: Ensure absence of downy mildew in the field. Starting in 1990 - inspect all plots and remove infected seedlings. 1999 - present: Allegiance fungicide (metalaxyl) seed treatment – gives systemic protection.
Sunflower disease management • A minimum of two field inspections are made before flowering. • Infected plants are pulled and removed from field. • Curatorial staff observe plant health through season. Downy mildew
Squash mosaic disease management Objective - prevent seed infection. 1. GH seedlings are tested prior to transplanting. 2. 3-5 plants in each peat pot are tested as a group. 3. Plants in any positive pot are re-tested individually or the pot may be discarded. 4. Transplants are grown in screened cages to exclude cucumber beetles.
Cost per accession for SqMV testing ELISA test kit $2.66 (0.38 x 7 wells)** Sample grinding bags $1.33 (0.19 x 7 samp.) Buffers $0.10 Latex gloves $0.42 Student labor at 8.00/hr $3.16 Tech labor at 25.00/hr $5.23 Avg. cost per accession $12.90 **Average of 7 samples per accession and ~1500 samples per season (based on2003 and 2004 data).
Questions? Contact: Charles C. Block, Ph.D. Plant Pathologist USDA-ARS North Central Regional Plant Introduction Station Iowa State University, G212 Agronomy Hall Ames, IA 50011-1170 Office: 515-294-4379 Fax: 515-294-4880 Email ccblock@iastate.edu