Young tomato plants in the greenhouse nursery have rotted the middle part of the leaves.
The pathogen is obviously systemic (vein-spreading). Is it familiar to anybody?
Dear Alex Ignatov ,
Can you provide more data about the condition of the whole plant (roots and stems incl.) and growing conditions (i.e. temperature, humidity, transplanting, possible vectors)?
From the look of it, I'd infer it's a fungal disease.
Can you also provide photos of better resolution? I'm not sure if I can distinguish fungal structure, for instance mycelia.
If the humidity was high, temperature between 15-22°C and it spread quickly on the adaxial side of older leaves, then to leaflets, petioles and the fruits, and a downy growth developed on the abaxial side, it's most likely late blight (Phytophthora infestans).
https://blogs.cornell.edu/livegpath/gallery/tomato/tomato-late-blight/
https://extension.umn.edu/disease-management/late-blight
Alternatively, it could be Botrytis blight.
Nicolò M. Villa Alex Ignatov
Agree on the needing of more background information.
The condition reminds me of tomato late blight with Phytophthora infestans as the probable causal agent.
Beside the necrotic lesions and chlorosis there appears to have the webby whitening faintly which would indicate the sporangiophores which are lemon sphaped and have a distictive papillate protrusion.
The use of a humid chamber and the use of cellophane tape slides can give the sporangiospores and their attachments for positive identification.
If all leaf wetness can be avoided the conditions for infection can be controlled and some fungicides treatments are also high effective.
Positive identification will be needed to get the right chemical control but environment and chemo therapy is probably needed.
Enclosed the late blight symptomatology on potato it is highly similar in tomato.
Paul Reed Hepperly I agree, just strange to see in the greenhouse in wintertime.
That seems to be bacterial blight by Pseudomonas syringae pv. syringae, in Mexico it's very common, mainly in greenhouses and in template climates under high levels of RH. Did you try to isolate it?
Finally, it was concluded that Pythium sp. caused such symptoms. It is hard to say exact species - something close to Pythium aphanidermatum.
- Badges
- Science method