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Rhizoctonia in disease-suppressing soil (left) and in sensitive soil (right) |
A disease-suppressive soil can drastically reduce the use of pesticides. Scientists of Plant Research International have discovered a new mechanism that is playing a role in the disease suppressiveness of soils.
In some soils all plants are affected by soil-borne diseases whereas plants remain healthy in other soils. Often, the cause of this suppressiveness is a mystery. Soils are full of bacteria, fungi and other soil life, all in interaction. This makes it difficult to discover which organisms are suppressing a pest or disease or, conversely, are stimulating them. In addition, results vary, depending on soil type, crop, pathogen, or other factors.
Despite this, our scientists have succeeded in unravelling an element of the disease suppressiveness of soils. They discovered that the lysobacter bacterium is playing a role in the suppressiveness of Rhizoctonia. This finding was a chance hit but it demonstrates that our scientists are using a good method to unravel suppressive properties. They collected a large number of soils from growers and compared these in a pot experiment by measuring all sorts of properties of soil and soil life. One or more of three related species of lysobacter were found in all soils that showed a good Rhizoctonia suppressiveness. The disease suppresiveness of the soil was also found to be higher with higher amounts of lysobacter in the soil.
Increase disease suppresiveness
The next step is the targeted increase of the suppresiveness of soils. For lysobacter this may be possible by adding growth stimulants, such as chitin or yeast. Ultimately, our scientists wish to draw up a list of measures that farmers and growers can use to give their soils such a suppressiveness that spraying against pests and diseases will hardly be required.
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