Meg McGrath, plant pathologist at Cornell’s Long Island Horticultural Research and Extension Center just added new images of pith necrosis infecting high tunnel tomatoes that she shot last season.
One of the telltale symptoms is the development of adventitious roots:
McGrath writes:
Pith necrosis is caused by the bacterium Pseudomonas corrugata, which is considered a weak pathogen able to attack tomato plants that are growing too fast. It occurs primarily in greenhouses with affected plants randomly distributed. Symptoms typically develop when first fruit are close to mature green. Disease incidence and severity is favored by high nitrogen fertilization, cool temperatures at night, high humidity, and plastic mulch. Nitrogen had been applied at a high rate in the high tunnel where the disease developed on Long Island.
The only strategy for managing pith necrosis is prevention by avoiding favorable conditions, in particular excessive nitrogen. Copper fungicides are not able to provide control because this soil-borne bacterial pathogen is inside the plant.