Causal Agent: 

Bacterium (Pseudomonas corrugata)

Hollow pith with browning
Characteristic Symptoms:
 
Infected plants may display chlorosis of the upper leaves with associated wilting.
 
Affected stem and petioles have brown lesion and stem pith are hollow.
 
Infected plants show profuse formation of adventitous roots.
 
Conditions for Disease Development:
 
The bacterium is soil-borne and waterborne.  It is considered a weak pathogen on tomatoes growing too rapidly.
   
High nitrogen fertilization, cool night temperatures, high relative humidity increase disease incidence and severity. Once the weather warms up, the plants tend to be able to outgrow the problem.
   
The disease frequently occurs when the first fruit set is close to mature green.
   
The disease appears to be quite difficult to spread by hand, clothing or pruning tools.
   
The pathogen may be seed-borne.
   
Management and Control:
 
Avoid excessive nitrogen application, especially when night temperature is cool. 
   
Remove infected plants as soon as symptoms are observed to minimize spread of disease from plant to plant.
   
Avoid conditions that lead to vigorous plant growth and wet plants.
   
Control root-knot nematode and root-feeding insects since they may help in disease establishment and spread. 
   
Biofumigation of soil using chopped mustard leaves can help suppress bacteria in the soil.
   
References:
Tomato Pith Necrosis (http://www.aces.edu/pubs/docs/A/ANR-0864/ANR-0864.pdf; http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/prm2859)
   

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