Help with stem rotting

[PhilipS]

This is my first post, and not surprisingly it is because I have got a problem! It is in our poly tunnel and is affecting peppers, aubergine, cucumbers, French beans, runner beans etc. I have attached some photos of the latest victim and while dissecting the stem I noticed the small red larvae I what is left of the stem. Any help and possible cause or cure would be really gratefully received
many thanks, Philip

[Jungle Jane]

Hi Philip welcome to the forum are you in the UK,I’ve never seen that pest before? What plant is the cut open stem from in pictures one & two?

[PhilipS]

Thanks for your response Jane. I am in N.Ire, so maybe only slightly damper than the rest of the UK! All the photos are from the same plant, but we have got it in aubergines, beans, and cucumbers.
regards

[Jungle Jane]

I’ve found a website with a similar looking pest,it’s in a different country but we have hundreds of midge species in the UK,having different host plants,this paragraph is interesting -
“At first, our question was whether or not the maggots were responsible for the observed symptoms. We determined that these maggots were gall midge larvae. There are several gall midge species with larvae that feed on decaying organic matter and fungi. One species of gall midge is known to cause direct injury to soybean; however, that species has not been found in South Dakota. It is unlikely that these insects were causing the brittle characteristics of the plants, but rather an additional symptom of another underlying issue.”
https://extension.sdstate.edu/small-...e-have-answers

[PhilipS]

Many thanks Jane that is very interesting and I think you have identified the larvae. As the article says they are probably not the cause of the rot but a bye product. I have done some more research myself and I am pretty sure the initial rot is due to Sclerotinia disease which I found an explanation of on the RHS website. If I am right I think the only answer is to change the soil. That’s a big job but probably worth it.
many thanks for your help, very much appreciated