[LynnieK]

Hello
I'm Lynnie and I'm new! I live in the north west highlands of Scotland.

I have noticed a few leaf problems this week in my polytunnel and wondered if I could get some help please (I am a beginner).

The first one is mildew, I think, and I've been told I need to cut off the affected leaves (it's a courgette plant, not yet flowerd/fruited).

The second one - I am not sure if it is a deficiency of some kind, or cucumber mosaic virus. It's on two or three of my cucrbits (not the cucumbers though)

The third one is on my tomato plants (not all) and I can't find any similar photos on google when I had a quick look.

Am really hoping theses are fixable problems :-(

Any help much appreciated.

[Yorkie]

Welcome to the site 

Although not relevant to your specific questions here, in future it might be relevant to remember whereabouts you are - could you add your general location to your forum profile?  Just click your username to edit the profile 

Now, to your piccies.

1. This doesn't look like the mildew I've had before, unless it is very very early stages.   I wonder if it's a nutrient deficiency.  What compost are the courgettes in, and what have you fed them with (if anything)?

2. Looks like a mosaic virus to me.  You're supposed to remove all affected plant material and wash hands / tools before touching unaffected plants.  However, when I've had it before, it hasn't been too extensive and I've just let the plant get on with it.

3. Doesn't look like blight.  How cold is it in your polytunnel overnight?

[LynnieK]

Hello Yorkie!

I've updated my location.

The courgettes are in general compost a mix of new and some that I had in a pot that I had used before (although cannot remember what might have been in it). I have not 'fed' them anything yet so I will give them some feed and see if that helps.

Re the CMV....do I need to just chuck those plants then and start again? I'll have to do some research and find out why I got the virus then....

Polytunnel does get quite cold - we've not had any frost for a while but it probably gets down to 2-3 degrees outside at night. During the day, it's been up to 40 in the polytunnel (we've had some pretty dry weather the last few weeks).

Thanks for the help.

[Yorkie]

You could add a general purpose feed, but at the back of my mind I've now got the possibility that it's just the usual leaf markings - if I recall correctly, some courgettes have markings.  Might be worth letting the courgette grow on for a bit to see if it thrives.

Not sure what to suggest re the CMV.  If you smoke, and don't wash your hands before handling plants, that can introduce viruses.

Tomatoes sulk if their temperature drops below 10C.  I wonder if your polytunnel is getting too cold for them at night; I'm not familiar with your climate.  Perhaps try some fleece over them till it warms up?

[BabbyAnn]

unlike other microorganisms that may not survive extreme conditions, plant viruses are very persistent - they are even present in seed so its origins are likely to be the growers who supply the seed for sale.

the "mildew" on the courgettes is most likely as Yorkie says - they are markings that are typical of that particular variety.

[LynnieK]

I don't smoke.

And I have have just read that CMV is often transmitted by aphids, but i've not seen anything like that yet this year. I know some mineral deficiences can cause yellowing on the leaves, that's why I was hoping it might be that, rather than the virus, as if it is the virus, it seems to have affected quite a few plants.....

You may well be right regarding the tomatoes....the plants are still quite small and are starting to flower.

Our climate is benefited a little by the Gulf Stream so it does not get nearly as cold/frosty as inland. It is a very wet climate generally, although last few weeks we've not had much rain and lots of sunshine - warm not hot. Also, I live just a few metres from the sea...as in very close...

[Yorkie]

Sunshine?  Wot's that then? 

[simonwatson]

The damage on the tomato leaf is definitely cold damage in my opinion. I've got a greenhouse full of plants in a similar condition. They're not dying back but they sure have stopped getting any bigger.

[aelf]

The courgette is fine, I think. Mine go like that every year (someone on here did explain what it's called but I can't remember) and I always get bumper crops.

Don't know about the others, sorry.

[JayG]

1) Agree, normal markings on many courgette varietis, not mildew.

2) Bit worrying, especially as growth looks poor - would be nice to think it might be starving but I'd move them away from more healthy looking relatives before trying a liquid feed.

3) Tomatoes can potentially suffer from so many diseases and also physiological conditions that it's sometimes difficult to tell exactly what's happening at a glance - I have seen similar leaf markings on semi-outdoor tomatoes (in a cold frame but with the lights removed when they outgrow it) - much head-scratching but the problem seemed to resolve itself without taking any action. Could have been too cold, maybe even sunscorch - in your case I suggest you keep a close eye on them, especially if the leaves start to curl or distort or the plants seem to be stunted compared to the others, in which case you would need to destroy them ASAP.

[mumofstig]

you may benefit form the Gulf Stream but you say yourself

it probably gets down to 2-3 degrees outside at night

even inside the greenhouse, without any heating, this will be much too cold for tomatoes  

I think the courgette is ok   but the yellowed leaf may have aphids/spider mite ? they can cause that kind of patchiness

[aelf]

I found the discussion that I was refering to re courgettes:

http://chat.allotment-garden.org/index.php?topic=38177.15

[Yorkie]

Thanks for that aelf 

[LynnieK]

Thanks everyone!

mumofstig.....yes, at the moment it gets quite cold at night but we do have warmer evenings in summer. we had the polytunnel up two years ago when we lived in a different house and it was right in the middle of a valley which got colder at night but we did get a lot of tomatoes so hopefully they will survive at this new house.

next year we are planning putting some heating into the tunnel over the winter though.

[mumofstig]

it probably will be ok in the summer, but it looks like cold may be killing the plants now - they don't often recover one they go blue