Gesundheit für Mensch, Tier & Pflanze

Bacterial spot of tomato

Xanthomonas vesicatoria (synonym Xanthomonas campestris pv. vesicatoria)

Profile

Bacterial fruit spot disease of tomato is caused by the bacterium Xanthomonas vesicatoria . Infection results in brown spots on leaves and fruit and can cause significant crop losses. Xanthomonas vesicatoria is listed as aUnion regulated non-quarantine pest.

Damage symptoms

Infections on leaves initially show dark green, watery spots on the undersides of the leaves, from which up to 3 mm large, sunken, round or irregular spots form. These turn gray or brown and are eventually also visible on the upper sides of the leaves. In some cases, the spots merge into elongated lesions. In severe infestations, the healthy tissue located between the infection sites is killed and breaks out of the leaves.

Slightly raised brown spots with a rough surface, 3 to 6 mm in size, form on the fruit. They are initially surrounded by a yellow halo.

Host plants

In addition to tomatoes, the most important host plants include plants of the genus Capsicum, especially peppers and hot peppers.

Distribution

The bacterium is widespread in tomato and bell pepper producing countries worldwide, especially in tropical and subtropical regions with moderate or higher rainfall. It also occurs preferentially in greenhouses.

Propagation and transmission

The bacteria cannot survive long in soil, but they persist in weeds of the nightshade genus(Solanum, e.g. Solanum nigrum) and on infected plant residues. The bacteria are spread by splashing water droplets and enter plants through stomata. On fruits, the infections happen through wounds (e.g. after insect bites, cracks,...). The disease is also transmitted with the seeds.

Economic importance

Bacterial fruit spot disease of tomato is found worldwide in regions where tomatoes or peppers are cultivated. Damage is caused by crop losses due to leaf drop and, in the case of fruit infestation, by the unsaleability of the fruit.

Prevention and control

  • Cultivation of resistant varieties
  • Maintain crop rotation of at least three years
  • Use of drip irrigation
  • Pruning only in dry weather or by hand; if knives are used for this purpose, disinfect them before each cut (preferably in 70% alcohol for one minute)

Phytosanitary status

Xanthomonas vesicatoria is listed as aUnion regulated non-quarantine pest and is transmitted through certain planting material. The presence of such pests leads to unacceptable economic consequences with regard to the intended marketing of the planting material. The import and movement within the EU are therefore uniformly regulated for specific seed and planting material.

Last updated: 15.11.2021

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