|
|
||
|
|||
|
|||
|
|||
Fusarium wilt of lettuce, caused by the fungus Fusarium oxysporum, f. sp. lactucae,
was first detected on lettuce in Arizona during the 2001-02 growing season and continues
to be found in lettuce fields from mid-October through early January. There is another
wilt disease of lettuce called Verticillium wilt, caused by the fungus Verticillium
dahliae. This disease has occurred in the Salinas Valley since 1995 but has not
yet been found in Arizona. The primary symptoms of each disease are similar and
consist of internal discoloration of the root cortex and plant wilting followed
by death. The internal root discoloration ranges from green, brown to black in plants
infected with Verticillium and reddish-brown to black in plants infected with Fusarium.
Since symptoms of both wilt diseases are similar, true disease identity only can
be achieved by bringing symptomatic lettuce plants to The University of Arizona
Yuma Agricultural Center, where the causal pathogen can be isolated from infected
root tissue and identified by microscopic examination. Both wilt pathogens are soil
inhabitants which can persist there for many years. Both pathogens also can be seed-borne.
The lettuce Fusarium pathogen can only infect and cause disease on lettuce, although
it may sustain itself on roots of other plants without causing disease symptoms.
Verticillium dahliae, in comparison, can infect and cause disease on numerous crops
other than lettuce. Management strategies for diseases caused by Fusarium oxysporum
and Verticillium dahliae are similar. When available, genetic resistance in host
crop plants can provide effective disease control. Soil fumigation and soil solarization
can reduce disease levels by lowering viable populations of both pathogens in soil.
On the other hand, no known fungicides applied after planting have consistently
and effectively managed diseases caused by Fusarium oxysporum or Verticillium dahliae.
To contact Mike Matheron go to: matheron@ag.arizona.edu.
|
|||
Back | |||
For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
|
|||
Home |
Cotton | Veggies |
Forages | Grains
| Citrus |
Crop x Crop Insects | Diseases| Weeds | Pesticides | Economics | News | Weather | Research | Photos | Contacts | General Info. Copyright © 2001 University of Arizona, College of Agriculture and Life Sciences Webmaster: Al Fournier (acis@ag.arizona.edu) |