Protection methods

- During cultivation

When symptoms are observed in a field of lettuce during cultivation, it is unfortunately too late to intervene. We do not have effective measures to prevent the progression of the disease: "the damage is done".

However, we can recommend reducing irrigations if they are too copious.

During harvest and at the end of cultivation, avoid burying too much plant debris in the soil.


- Next crop

As the “cork pivot” symptom occurs especially in plots where lettuce is grown on lettuce, be carried out crop rotations should fairly long if possible. For example, following rotations with sugar cane, a reduction in the damage of has been observed Sphingomonas suberifaciens . Burying green manure will improve soil structure and temporarily reduce “infectious corky root”. Such results were obtained in the USA by burying rice 3 weeks before planting. The next time a lettuce crop is set up, it will be necessary to plow the soil deeply and work it to improve its texture; we will also promote its drainage.

The disinfection of the soil with a fumigant is effective. Dazomet has shown good efficacy in California.

The salads will be planted on mounds and the irrigation will be controlled as best as possible to ensure that the plants take deep root. It will be preferable to use seedlings than to carry out direct sowing. Excessively prolonged irrigations, which cause soil water saturation, should not be carried out, especially during the early stages of seedling growth. It is during the latter that the disease begins. The irrigation sprinkler or localized seems less conducive to disease as watering furrow.

Soil analyzes will be carried out in order to check that the latter does not contain high residual nitrogen concentrations. It will be better to use forms of fertilizer that release nitrogen slowly.

A monogenic resistance recessive is known in the genus Lactuca (gene " horn "). This resistance has been introduced into the United States in some cultivars. Unfortunately, strains capable of circumventing this resistance have appeared. The latter is not present in French cultivars of lettuce.