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Agricultural Research & Education Center
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Bradenton AREC Research Report BRA1983-1 January 1983
PITH NECROSIS OF TOMATO
J. B. Jones, J. P. Jones1 and J. W. Miller2
Pith necrosis of tomatoes is incited by the bacterium, Pseudomonas
corrugata Roberts and Scarlett. The pathogen has been reported on greenhouse-
grown tomatoes in England (5) and Germany (4) and on alfalfa in the U.S. (3).
The disease recently has been detected on field grown tomatoes in Florida (1)
and California (2). In Florida, the disease was first observed in the Manatee-
Ruskin area, but has since been observed in 19 other counties (1).
During the early growth stages of tomato plants, the disease appears to be
extremely destructive, with affected plants appearing to be lost to production.
However, with the advance of warm weather, the disease becomes far less
noticeable and the plants eventually grow out of the condition except for the
occasional death of a few isolated plants.
The disease appears to be favored by a regime of high humidity, moderate
temperature (75-850F, unpublished data) and high nitrogen fertility which
results in extremely succulent and susceptible vegetative growth (5). A
limited study with four tomato cultivars revealed varying degrees of
susceptibility (2). None of the cultivars tested is grown commercially in
Florida. The source of inoculum is unknown. In England, the bacterium has
been isolated from water sources used for tomato production (5). In the
first report of this bacterium in the U.S., it was isolated from healthy roots
of greenhouse-grown alfalfa (3). Weed species potentially could harbor the
bacterium for infection in tomato crops.
Symptoms: A diseased plant is readily detectable by the yellowing of the
younger foliage. Affected areas have brown, sunken, necrotic stem lesions.
Longitudinal cuts through affected stem tissue reveals a chambered pith.
Brown discoloration of the pith or complete pith collapse often extends a
IAssistant Plant Pathologist and Plant Pathologist, AREC-Bradenton.
2Plant Pathologist, Bureau of Plant Pathology, Division of Plant Industry,
P.O. Box 1269, Gainesville, FL 32611.
considerable distance past the external browning. Vascular browning often
extends up and down the stem beyond the pith discoloration. Adventitious
roots proliferate on the stems of affected plants. As the plants continue
to grow$ symptoms become less noticeable and the plants appear to recover
completely from the disorder.
Control: Spraying plants with a copper-EBCD combination prior to
pruning and tying may help to reduce potential spread. Avoid over fertilization
especially with nitrogenous fertilizers.
1. Jones, J. B., John Paul Jones, R. E. Stall, and J. W. Miller. 1983.
Occurrence of a stem necrosis on field grown tomatoes incited by
Pseudomonas corrugata in Florida. Plant Dis.:(in press).
2. Lai, M., D. C. Opgenorth and J. B. white. 1983. Occurrence of Pseudomonas
corrugata on tomato in California. Plant Dis. 67:110-112.
3. Lukezic, F. L. 1979. Pseudomonas corrugata, a pathogen of tomato isolated
from symptomless alfalfa roots. Phytopathology 69:27-31.
4. Naumann, K. 1980. Die bakterielle stengelmarknerose der tomate ein
neues Krankheitsbild in gewachshauskulturen. Nachrichtenblatt fur
den Pflanzenschutz in der DDR 34:226-231.
5. Scarlett, C. A., J. T. Fletcher, P. Roberts, and R. A. Lelliott. 1978.
Tomato pith necrosis casued by pseudomonas corrugata n. sp. Ann. Appl.