Tomato botrytis question

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Tomato botrytis question
« on: June 15, 2013, 16:43 »
This year I am leaving the allotment greenhouse door open most nights when warm enough for tomato humidity reasons. But this policy is not a good idea for my chillies and cucumbers, and I have now noticed even with an open door, unwanted condensation still appears on the greenhouse border tomato foliage in the mornings. I thought this wet was condensation from the greenhouse roof. I now know this wet is not from the roof, but the leaves themselves insist on forming condensation overnight, and hence the perfect conditions for a repeat of last year that took a lot of management to get a crop.

Any tomato experts out there with an opinion of how to keep the condensation off the foliage ?While my cucumbers don't really like it, I'mthinking leaving the door open is the right thing for my botrytis tomato watch, but am I right ? And when the inevitable blight appears locally outside, I'm sure I will want to close the door to keep that out with the inevitable worry of high humidity botrytis. I've got plenty of Bordeaux mixture handy that seems to still hang onto it's organic status ... sort of.

How about fleece actually over the tomato foliage itself at night to try and keep it warmer than the rest of the open greenhouse/outside ? Basically I'm trying to keep the foliage dry and free of condensation and it is already proving very difficult, and it's not even high Summer yet. Any suggestion from those far more experienced than myself ? I'm certainly not into trying to keep the greenhouse heated over night... that's not an option.
« Last Edit: June 15, 2013, 17:08 by seaside »



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Re: Tomato botrytis question
« Reply #1 on: June 15, 2013, 17:05 »
All I can think of is to give them a good water in the morning (if you're not already) as opposed to the evening, so that there's less water to condense overnight...
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Re: Tomato botrytis question
« Reply #2 on: June 15, 2013, 17:08 »
Personally I've never known it to be a problem. Plants transpire giving off moisture so its normal, transpiration rates are affected by heat, humidity etc so will become more noticable in more humid conditions as the moisture transpired will not evaporate from the leaves as readily.

For the last year or 3 I haven't had a door on my greenhouse so in effect its open all the year round. Never (touch wood) suffered with blight inside the greenhouse, even when it was on my spuds in the garden. Quite likely more luck than judgement.
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Re: Tomato botrytis question
« Reply #3 on: June 15, 2013, 18:01 »
The condensation only seems to happen on cold nights, I find - we've had a few of them lately. I only used to get it when it started to get cooler in the Autumn, but the last few years it has been happening more often :(

Leaving the doors open should mean that it will evaporate off quickly in the morning with the extra airflow. I don't see what else you can do tbh. I think that fleece would just hang onto the moisture even more.
Lesley x
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Re: Tomato botrytis question
« Reply #4 on: June 15, 2013, 18:59 »
Leaving the doors open should mean that it will evaporate off quickly in the morning with the extra airflow. I don't see what else you can do tbh.
That's what I thought would happen, and it certainly is a conundrum Mummy, that's for sure. Just makes me wonder what on earth the point is in telling folk to not water over the tomato foliage, apart from the normal water the roots advice for plants in pots.
Nik.... I never thought it to be a problem either until last year when the botrytis suddenly ran rampant throughout the whole greenhouse.... I nearly ditched the whole greenhouse on some advice but I'm glad I didn't as I got a reasonable crop, but I'm sure there is an answer to my husbandry that will improve my plants.
What I find difficult to understand is that my accompanying greenhouse chillies, aubergine and  cucumbers have no such overnight leaf condensation problem ... it just appears to be the tomatoes.
I'm aware having open border beds in the greenhouse make the matter worse, and I guess I'm going to have to try a controlled experiment over the next fortnight now I know what the problem is. Eradicating condensation from below ground cellar walls is easier.
Still, no immediate rush as I don't expect galloping grey mould, or blight for that matter, to strike before July.
If I come up with any useful findings, I'll be sure to post them here.
« Last Edit: June 15, 2013, 19:12 by seaside »



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Re: Tomato botrytis question
« Reply #5 on: June 15, 2013, 20:05 »
I think it would be better to have air flow is there a window you can open too?



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Re: Tomato botrytis question
« Reply #6 on: June 16, 2013, 14:36 »
You must be right that more air flow will mitigate problems from any daily wetted foliage due to condensation, but there comes a time when a greenhouse is not a greenhouse, just a shelter from the rain... in the end, there is a temperature to consider, especially for those fussy cucumbers.
My greenhouse is not a sealed shop bought unit and I built it ( and well built I might add ) from 2x2 timber and UV treated 4mm polycarbonate twin wall sheeting with the express intention to allow some "leaks" and drafts in normal weather conditions in the Summer. Winter time is a totally different strategy and I plug all breaches.
I'm sure the open soil borders inside, where the tomatoes are planted, are having a moisturising effect. I've left the greenhouse today in a different configuration with fleece over the offending tomatoes to warm them up a bit. Might not help their immediate air circulation but might just keep the foliage warm enough not to condensate as they have been doing every night.
« Last Edit: June 16, 2013, 14:41 by seaside »


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