| 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 30°C.; 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........... |
- 10°C |
|
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 24°C or 12 hours at 16°C. |
| |
| INCUBATION
|
| |
| Location................. |
Greenhouse; transplanted into benches or
tub |
| Temp/Light............. |
20°-24°C; 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
|