What is the cause of these symptoms?
This is a bean. The weather is very hot.. maybe 35℃.
The symptoms of this lesion, each node has been generated from.
I would like to know the exact cause. If this is caused by pathogens,
What type of pathogen is it?
If that is not caused by pathogens, what is other cause?
Outside United States
What kind of bean - It looks like soybean so I am assuming that but it could be something else such as mung beans or adzuki beams. Also what location? All I see is "outside the U.S." Diseases can vary a lot by location. It appears to be a soil borne fungal disease, possibly a Fusarium and possibly SDS - Sudden Death Syndrome, caused by different Fusarium species and sub species depending on geographical location. This is one reason it is difficult to know what you might have. Best bet is to check with a local plant pathologist specialist who should be familiar with the possibilities. Also it can be very difficult to diagnose with certainty fungal diseases without microscopic examination of the diseased plant and successful management strategies will often differ with location so local specialists are important for diagnosis and management. Mung beans are also susceptible to some forms of SDS, at least in the U.S. I am not sure about adzuki beans.