Tomato Pith Necrosis

Tomato pith necrosis, a newly emerging disease of tomatoes, is caused by Pseudomonas corrugata and appears to develop when there are low night temperatures, high nitrogen levels and high humidity.  The bacteria may be seed-borne but the epidemiology is poorly understood.  

Tomato pith necrosis has been found in the Nova Scotia greenhouse tomato crop this season.

Early symptoms of this disease include wilting of foliage and chlorosis of older leaves.  Dark brown to black lesions develop on the surface of lower stems (Picture 1).  Vascular tissue may be brown. Adventitious roots may grow profusely from these symptomatic stems.  It may resemble that of bacterial canker.  This disease may affect the fruit as well (Picture 2).

 

 

Picture 1 Tomato pith necrosis lesions on stem 

Picture 2 Tomato pith necrosis symptoms in fruit

 
 
 
 
 
 
 

 

Growers should avoid using excessively high nitrogen rates, should not use overhead sprinklers on field tomatoes, and remember to sanitize pruning shears.  In field tomato, keep good crop rotation and control volunteer tomato and nightshade weeds.

New Disease of Celery Detected in NS

A disease of celery first noticed in Michigan and Pennsylvania during the 2010 and 2011 growing seasons, and in Ontario in the 2012 growing season has now been detected in Nova Scotia's celery fields.  The disease, caused by an anthracnose fungus Colletotrichum acutatum, is known as Leaf Curl, and was positively identified earlier today.

The disease causes malformed cupped-leaves, downward curled leaves, the development of lesions on the stalks and eventually twisting of the stalks.  The disease symptoms are similar to symptoms of several other diseases of celery.  Infected celery plants are not marketable.  (Clicking on the picture below will enlarge it.)

An OMAFRA vegetable blog suggests that fungicides with action against early and late blight of celery may also have action against leaf curl.  For information on fungicides registered for celery in Nova Scotia see the Guide to Pest Management in Celery beginning on page 8.

Michigan State University Extension has published an very informative article, Celery Anthracnose: a newly identified fungal disease of celery, which includes a number of pictures and frequently asked questions.