Dear all
I received this picture from melons farmer. I wanna know what the cause of these symptoms on the leafs is? Based on data from farmer these symptom has been seen around 40% of plants and they have been extended Gradually.
would you please tell me that it is related to leaf spot or phytotoxity and if this is leaf spot, what kind of fungi?
Dear Elaheh Germani,
Seems like this is Anthracnose caused by Colletotrichum orbiculare seen in muskmelon, watermelon, cucumber. Anthracnose symptoms consists of black spots which are angular and irregular, jagged in appearance. Here, the attached picture also shows the same types of symptoms.I dont think this is symptoms of Phytotoxicity. There is a bulletin available online from Purdue University, USA. Please have a look. I am giving the link
https://www.extension.purdue.edu/extmedia/bp/bp-180-w.pdf
Dear Sesha Kiran Kollipara thanks for your kind reply. i really appreciate it if anyone else has other idea?
If you suspect that it's not anthracnose. Perform ooze test by cutting infected part and placing it in the drop of water on the glass slide. If you feel there is cloudy ooze coming out, then it might be the bacterial infection. But ,based on the symptoms, i don't think these angular lesions are caused by bacterial infection. But, still, you can crosscheck.
i don't think that is symptome of anthracnose, Dear Elaheh, the farmer need to verify the pesticide or intran. verify the product used
incubation of the leaf sample under moist conditions in a Petri plate for overnight and observing on the next day for the presence of reproductive structures under the microscope will give a clear idea if it is phytotoxicity symptoms or pathogen infection. Also, surface sterilise symptomatic tissue and place it in sterilised nutrient media. If any fungal infection is there, then u can observe. Once you get pure culture , you can study pathogenicity tests n identify the fungus.
Dear all
After evaluating in laboratory, this symptoms is not related to fungus and this is caused by using of pesticide overdose . I really appreciate for your help.
Microscopic observation for presence of fungal mycelium, reproductive structures such as spores is best . If they are not present , then fungal infection is ruled out. Ooze test makes you confirm if it is bacterial infection or not? You can take a fresh plant devoid of symptoms and repeat the application of same pesticide under controlled conditions you are suspecting to have caused this anthracnose like symptoms which are angular in nature. If you r getting symptoms in this conditions , you can double confirm . Any way, we also got some knowledge of pesticidal injury which are akin/mimicking fungal disease symptoms.
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