Final diagnosis


Pratylenchus spp.

These two lettuces parasitized by nematodes are chlorotic and small in size. <b> <i> Pratylenchus penetrans </i> </b> ("lesion nematodes")
Roots infected with endomigratory parasitic nematodes become covered with numerous lesions, initially moist, yellowish to reddish brown. Ultimately, the entire root system is affected, as is the case with these three salads. <b> <i> Pratylenchus penetrans </i> </b> ("lesion nematodes")
All the roots of this salad show a uniform reddish-brown color. <i> <b> Pratylenchus penetrans </b> </i> ("lesion nematodes")
The attacks often occur early; this was the case with this root system, the oldest part of which is completely rotten. <b> <i> Pratylenchus penetrans </i> </b> ("lesion nematodes")
The roots are often devoid of rootlets; the cortex can be entirely degraded. <b> <i> Pratylenchus penetrans </i> </b> ("lesion nematodes")
<i> Pratylenchus </i> are fairly short nematodes with a prominent buccal stylet. <b> <i> Pratylenchus penetrans </i> </b> ("lesion nematodes")