Identifying a Disorder Found on a Hybrid Blackberry Plant

[Emmanuel_Albazi]

Hello Everyone...
I hope you all are doing well...

First i want to mention that about 3 years ago a friend gave me a hybrid blackberry plant but unfortunately i did not know what type it was but i guess it is Boysenberry and it was doing very well during those years and I faced no problem at all.

But today I was Checking the plant to see how it is doing and I found these yellow spots on two leaves that are located near the soil

But other parts of the plant seems fine and healthy (even those with the yellow spots).

My questions are
1-what are those yellow ovally shaped spots and what causes them?
2-how serious are they if left untreated and how to manage it?

I will be very thankful with anyone who can give me an answer.

 

[Chuck]

Most fungal diseases have brown spots but usually there is a yellow halo around the brown. At this point all I would do is remove that leaf and keep a close watch on the plant to see if any more spots appear on other leaves. My guess as to why the leaf has the spots is that the spots were from an injury from an insect bite. If any spots do appear spray with either a copper fungicide or with Neem Oil.

 

[Emmanuel_Albazi]

Most fungal diseases have brown spots but usually there is a yellow halo around the brown. At this point all I would do is remove that leaf and keep a close watch on the plant to see if any more spots appear on other leaves. My guess as to why the leaf has the spots is that the spots were from an injury from an insect bite. If any spots do appear spray with either a copper fungicide or with Neem Oil.

Thanks for the giving me an answer. I also thought that it may be a fungal infection or because of the high temperature ( above 35 degrees Celsius) or because of an insect.

I have not seen any insects yet and the leaves did not have any damage (eaten or holes on leaves with the spots). My third hypothesis is maybe true but it did really well last year during the summer when the temperature reached 45 degrees Celsius.

So i think i need to remove the leaves with the spots as you recommended and to carefully check the plant regularly.

 

[Chuck]

Thanks for the giving me an answer. I also thought that it may be a fungal infection or because of the high temperature ( above 35 degrees Celsius) or because of an insect.

I have not seen any insects yet and the leaves did not have any damage (eaten or holes on leaves with the spots). My third hypothesis is maybe true but it did really well last year during the summer when the temperature reached 45 degrees Celsius.

So i think i need to remove the leaves with the spots as you recommended and to carefully check the plant regularly.

High ambient temperatures such as yours actually deters fungal growth. High humidity is what encourages fungal growth. Plant fungi prefers a humidity of about 70% and an ambient temperature of about 25C.

 

[Emmanuel_Albazi]

High ambient temperatures such as yours actually deters fungal growth. High humidity is what encourages fungal growth. Plant fungi prefers a humidity of about 70% and an ambient temperature of about 25C.

You are right but the weather in my location is actually very dry (dry+hot) but since the spots are located near the soil where humidity is definitely high.

Thank you again for the help...i will remove the damaged leaves as soon as possible.

Note:- we are in the spring season now where the temperature is usually between 20-35 C. So it is probably a fungal infection.