March, 1995                                                                                                      PDF Version

Bacterial Wilt Resistance - Greenhouse/Controlled Environment
Clavibacter michiganense subsp. insidiosum (McCull)Davis et al [Syns. Corynebacterium insidiosum (McCull.) 
H.L. Jones] J.E. Brummer and S.L Nygaard

PLANT CULTURE
  
Container................ Bench or tub with adequate depth for root development (6-8 inches)
Media..................... Soil Mix (1:2:1; Top soil: sand:sphagnum/perlite) adequate lime and fertilizer (0:24:24)
Temp/light............... 24 to 30C.; 16+ hour daylength
No. of Plants............ 50-60 per replication
No. of Reps............. 4 replications
Other...................... Inoculate with Rhizobium meliloti
  
INOCULUM CULTURE
  
Source................... Infected root tissue
Storage.................. Washed frozen root tissue
Temperature........... - 10C 
Storage Life............ Several years if tissue remains frozen
  
INOCULATION PROCEDURE
  
Age of Plant............. 8 weeks old
Concentration.......... 100g ground infected root per IL H2O
Method................... Clip roots (6-8 cm from crown) and bare root soak
Type of Inoc............. Bacterial water suspension
Time of Inoc............. 20 min at 24C or 12 hours at 16C.
  
INCUBATION
  
Location................. Greenhouse; transplanted into benches or tub
Temp/Light............. 20-24C; 16 hour daylength
Culture................... Clip top growth twice at 5-6 week intervals (at bud or bloom) maintain good growth and control insect pests; fertilize (0-24-24) after each clipping.
Spacing................. 2.5 cm between plants and 6 cm between rows
Age of Rating........... 12-14 weeks after transplanting
  
RATING
  
Plants are removed from benches and tap root is sectioned for rating.
  
Resistant................ Symptomless root or less than one-fourth of the stele expressing a yellow-brown discoloration (discrete small spots).
Susceptible............. Discoloration in the root greater than one fourth of the entire root (stele and cortex); dead plant.
  
CHECK CULTIVARS
  
  Approximate Expected Resistance Acceptable Range (%)
Resistant    
Vernal** 40 30-50
Susceptible    
Narraganset** 2 0-5
Sonora** 2 0-5

 

CORRELATION TO FIELD REACTION

There is a good correlation between results of this test and visual root scores and plant vigor in naturally infested fields.

 

SCIENTIST WITH EXPERTISE AND SOURCE OF INOCULUM
  
Name..................... Deborah Samac
Address................. USDA-ARS
495 Borlaug Hall
1991 Upper Buford Circle
University of Minnesota
St. Paul, MN 55108
Phone.................... (612) 625-1243
  
REFERENCES

See Bacterial Wilt field protocol; In: STCAC

Previous Page