Final diagnosis


Various Oomycetes (Damping-off, root rots, crown and fruit )

The absence of germination or the collapse and rapid disappearance of seedlings characterize the damping off. In this case, the population of etiolated seedlings became very sparse following an attack by <b> <i> Pythium ultimum </i> </b> (damping-off, damping-off, root rot and basal stem canker)
Closer, we find that this lesion is wet, blackish, and that it surrounds and strangles the stem for several centimeters. <b> <i> Phytophthora nicotianae </i> </b> (root and basal rots, foot and root rot)
A moist, brown canker develops in the lower part of the stem and at the taproot. The roots emerging in this area degrade and also turn brown <i> <b> Phytophthora nicotianae </b> </i>.
The foot of this tomato has a wet, black lesion. The nearby roots are brown and weathered. <i> <b> Phytophthora nicotianae </b> </i> (<i> Phytophthora </i> crown and root rot)
On this older plant, the roots near the bottom of the stem are brown and rotten. The rot gradually gained the collar which took on a blackish tint. <i> <b> Phytophthora nicotianae </b> </i> (<i> Phytophthora </i> crown and root rot)
<b><i>Phytophthora nicotianae</i></b> (mildiou terrestre, downy mildew)
Root system altered by <b> <i> Phytophthora nicotianae </i> </b> (terrestrial downy mildew)
Several root systems of this soil-less tomato crop show significant root losses resulting in more or less marked browning. <b> <i> Pythium </i> spp. </b> (damping-off, root and basal rots, damping-off, foot and root rot, buckeye rot)
In this rock wool bread some brownish roots are visible in places. <b> <i> Pythium </i> sp. </b>
Still healthy white roots and yellowish roots colonized by a <b> <i> Pythium </i> sp. </b> are visible in this fragment of rock wool recovered in a bag
Note that <i> <b> Phytophthora nicotianae </b> </i> induces irregular brownish rings on the fruits, which are more or less scalloped and have concentric patterns reminiscent of a target. (<i> Phytophthora </i> crown and root rot)
Large dark brown scalloped alterations partially cover these green fruits. <b> <i> Phytophthora nicotianae </i> </b> (terrestrial downy mildew)
These two fruits are largely covered by one to several vaguely target-shaped lesions, consisting of concentric bands, dark brown, diffuse and more or less scalloped. Note that the fruit surface remains smooth and firm. <i> <b> Phytophthora nicotianae </b> </i> (<i> Phytophthora </i> crown and root rot)
Large brown spots, consisting of concentric rings with scalloped contours. <i> <b> Phytophthora nicotianae </b> </i> (soil mildew, soil mildew)
Concentric brown half-rings with scalloped contours. <b> <i> Phytophthora nicotianae </i> </b> (terrestrial downy mildew)
Filamentous sporangia of <b><i>Pythium aphanidermatum</i></b> .
Globular and empty sporangium of <b> <i> Pythium </i> sp. </b> carrying a discharge tube.
Filamentous sporangium of <b> <i> Pythium </i> sp. </b> containing several zoospores.
Two sporangia of <i> Phytophthora cryptogea </i> formed on the outside of this necrotic and rotten tomato root, taken from a soilless crop. Usually the sporangia of <i> Phytophthora </i> spp. are formed more readily in the tissues. <b> <i> Phytophthora </i> spp. </b> (root and basal rots, foot and root rot, buckeye rot)
Young ovoid, unpappalled sporangium of <i> Phytophothora cryptogea </i>. <b> <i> Phytophthora </i> spp. </b> (damping off, root and basal rots, damping-off, foot and root rot, buckeye rot)
Numerous oospores have formed in the cells of the cortex of this altered root <b> <i> Pythium </i> sp. </b> (damping-off, root and basal rots, damping-off, foot and root burp)
Round, thick-walled oospores more or less fill the cells of the cortex; they frequently materialize the presence in the roots of <b> <i> Pythium </i> spp. </b> (root and basal rots, foot and root rot, buckeye rot)
<i> Pythium spinosum, P. periplocum </i> ... form more or less ornamented oogonia which are at the origin of oospores. One of the three structures present can be referred to as an aplerotic oospore. <b> <i> Pythium </i> spp. </b> (damping-off, root and basal rots, damping-off, foot and root rot, buckeye rot)