tomato leaf mould

[jayjaybee]

Hi guys
Not sure whether this question should be here or in the Under Cover Operations thread. My tomatoes in the greenhouse have tomato leaf mould as they did last year. I have followed advice and removed lower leaves, waterered in mornings, albeit not often as they have undergroung irrigation. I leave the door open whenever possible to ease humidity, much to the digust of the cucumbers! I tried spraying with camomile tea earlier in the season but it is coming back again. I do admit to perhaps growing too many in a small space, but couldn't help myself . I am slowly removing leaves that show the early signs of mould. I fear I'm a lost cause this year, but what can I do to prevent it next year?

[Scarlet]

I do admit to perhaps growing too many in a small space, but couldn't help myself . I am slowly removing leaves that show the early signs of mould. I fear I'm a lost cause this year, but what can I do to prevent it next year?

I think you know the answer yourself. How far apart are your plants spaced? Mine are planted in a double row in a zigzag formation with 18inches between plants. Tomatoes need plenty of airflow. Doors should be left open ...you say "whenever possible ", I haven't closed mine for weeks. are your windows auto or are you opening them yourself?

[jayjaybee]

Hi Scarlet thanks for your input.
15 inches apart in a 6x8 greenhouse 5/6 plants along the long side. Having removed lower leaves and those shading trusses, I am confident there is adequate airflow, with auto roof vent and lower auto louvre. When temps at nigt are still only 10, am reluctant to leave the door open, but will consider it. Half the problem could be lack of sunshine and the wet humid aatmosphere we have had so far, which doesn't help. I think I am stuck with the mould this year but any advice on how to stop it overwintering into next. I do wash down and clean the greenhouse annually, even changed the soil early this season. I might even consider chemical warfare (we live near Porton Down so it is in the blood) but not this late when the fruita are forming/ripening. Perhaps some sort of fumigation in the winter. I will perserve. The toms are forming and beginning to ripen.

[Scarlet]

Well, I'm just a stones throw away from you. The doors on my GH don't get closed and they are doing well. If you are watering in the mornings it may be wise to dig in some milk bottles and water into those, mulch the beds and your GH should be dryer which will help.

What do you wash your GH with?

Can you post a photo of the mould and also a photo of the GH with your plants in?

[bearded bloke]

Yep, what Scarlet says ^^^

I consulted the 'bible' & Dr. Hessayon says ..
Treatment, remove some of the lower leaves ..
Prevention, Ventilate the greenhouse, especially at night

I don't know why you are reticent about leaving the door open overnight, but you could help allieviate some of the humidity by removeing the apex glass in both ends of the greenhouse to get a high level through draught.

[jayjaybee]

Will take on board the comments about overnight opening. Have researched and concensus was that temps below 13 deg C would prob cause blossom drop so was erring on the cautious side, plus habit of course.
Will attempt to take a pic of the jungle I call my greenhouse but may not be for a day or two. I clean gh with soapy water. Did it one year with J's fluid and the chemical ate all the plastic glazing strip. Usually take all the roof glass out and give a good scrub as well as washing down the structure.
by the way notwithstanding leaf mould, toms are thriving.

[jayjaybee]

Scarlet &BB
when in the spring (or at what nighttime temp) do you consider it ok to leave the gh door open overnight?
By the way took your advice, door now remains open. Am going away for 4 days so I will have to rely on undersoil irrigation totally. When the garden prevents awaydays or weeks I wonder why we bother, but then a dinner plate full of home grown reminds me.

[Scoot]

Scarlet &BB
when in the spring (or at what nighttime temp) do you consider it ok to leave the gh door open overnight?
By the way took your advice, door now remains open. Am going away for 4 days so I will have to rely on undersoil irrigation totally. When the garden prevents awaydays or weeks I wonder why we bother, but then a dinner plate full of home grown reminds me.

As long as the night time temp stays at around 10C, everything should be fine.

The temps have been getting to around 9C around here recently and my toms look just fine with the door been left open all night.

[jayjaybee]

Sounds like a plan for next year. Thanks.
even looking into an old veg growing book for dire chemical remedies, it says if the problem persists year after year, grow resistant varieties. I have noticed that certain plant are more susceptible than others. Maybe that's a further plan.

[bearded bloke]

In my case the timing for the door to be left open overnight is controlled by Mrs.BB, the 'undercover' veg is grown in her greenhouse which is mainly used for cacti & succulents, the door is left open for an ever increasing time (after about 5 degrees) to re-acclimatise the larger Aloe's prior to putting them out after a two week period with no overnight frosts

[Scarlet]

I keep my eye on the temperature end of May and beginning of June. Remember that a dip to 9/10 for a couple of hours is nothing compared to low temps through the whole night. The GH should also be a few degrees warmer than outside and as the plants are much bigger they aren't really affected. My chillies are in the back of the Gh without a problem.

If you are away for a few days, I would water really well the day before and mulch the ground heavily/or cover in some plastic bags/newspapers etc.

I do think that you need to clean out the GH with something a little more than soapy water if you have an ongoing problem. Personally I would use something to sterilise the lot. If you don't want to use ***** look at something else that will give it a deep clean.

[bearded bloke]

With regard to cleaning, I wash the glass & framework with bleach diluted in warm water, usually takes 2/3 goes before all the algae is gone, at which point I usually determine it to be clean enough, although one year I went a bit OTT & removed all the glass so as to totally clean the overlap, Mrs.BB was so mightily impressed she took me down the pub for a steak supper

[Ryez]

Yes, tomatoes seem to be doing fine with the low temperatures at night, I never close the door either anymore, mainly because mine got aphids so I need all the beneficial bugs to fly in and out freely.

[MarkPelican]

I agree with scarlett, my polytunnel has doors at each end and the rear door (which admittedly faces a brick wall) has been open six inches since the start of May. The front door has been either fully open or partially open every night bar one since the end of May.

In previous years, I've grown my tomatoes in the unheated polytunnel, sowing them in February and covering them with fleece until late April.

My own experience is that aborted flowers (or blossom drop) seems to be caused more by the temperatures getting too high (40C +) rather than too low.

For the first time this year I've been running a set of temperature sensors which record the maximum and minimum temperature every hour outside (I haven't yet stretched it into the polytunnel). I started in early June and since then I've had three days when the minimum temperature outside was below 10C. In each case it was there for a couple of hours and I don't think that's enough to cause any problems.

[jayjaybee]

It's over a year since I originally posted my problem about tomato leaf mould. I took on board the advice of the grapes, scrubbed, sterilized and ventilated the greenhouse. Thanks to you I am mould free this year. The tomatoes are healthy and taking over the world. Thank you for all your advice. The grapes rule!