Main symptoms

As its name suggests, Ralstonia solanacearum leads to rapid wilting of young leaves at the hottest times of the day, often reversible during the night at first (Figures 1 to 4). Subsequently, the wilts appear suddenly and become permanent. It should be noted the total absence of symptoms on fruits. Fairly quickly, the affected tissue dies and dries up, and many plants die eventually. Less typical symptoms may appear, especially in conditions that are not favorable to bacterial wilt: slowed growth of plants, leaf epinasty, emission of rough root blanks on the stem, yellowing of lower leaves These different symptoms can appear on young seedlings in the nursery as well as on adult plants. The roots could suffer from the presence of R. solanacearum : an increasing number of them would rot .

In all cases, a longitudinal cut in the roots, the taproot and the stem often shows that the vessels have taken on a yellowish to brown more or less dark color (figures 5 to 7). At the end of the course of the disease, the marrow and the cortex can present wet and brown lesions.


A very simple method, known as the “ glass of water test ”, makes it possible to make a very effective complementary diagnosis of contamination by R. solanacearum in order to  differentiate it from an attack by a vascular fungus. It consists of taking a fragment of a stem from the lower levels of the stem and immersing it in a glass of water: within 5 minutes appear white volutes made up of billion bacteria (the disease had for first name the "thread disease" due to this property) (figure 8)

Figure 8