Saturday, July 19

Stripy Tomatoes

Those of you who visit Martyn's blog will already know that this year

 our tomatoes problems have moved from the garden greenhouse to the plot greenhouse.

Suddenly between visits to the plot - we try to go every other day - some of our tomato plants looked to be struggling. Two varieties Amish Gold and Sioux are failing. Sioux was our best cropper in the plot greenhouse last year but this year has developed brown stripy tomatoes and the tops of the plants have curled. The sickly plants are those either side of the door.

Advice from the RHS point to the plants being under stress which it is suggested could be due to poor ventilation leading to too high temperatures in the greenhouse. This is feasible as, although we have an automatic roof vent, the door is rarely left open. If it becomes windy we can't just quickly shut the door as we would for the home greenhouse, or quickly respond to any other changing conditions. Also as blight was about on the plot it seemed right to keep the greenhouse shut to offer some protection against the tomatoes being attacked




The greenhouse does have side vents that Martyn has now rigged up so that they remain open and yet protected against entry of birds that could otherwise become trapped inside.

You would expect, however if the tomato problem was caused by poor ventilation that all the plants in the greenhouse would suffer but only plants in two of the growbags seem affected, in fact we are picking ripe fruit from the Sungold plants.
Going back to our poorly tomato plants - I also sent this photo of the lower leaves of the ailing plants to the RHS. In response to the photo the RHS wrote suggested it was possibly a magnesium deficiency and to try applying Epson Salts. They added that the compost in the growbags could be - 'sub-optimal' - this can occur with peat-free and peat-reduced bags. It was suggested that we flush the bags with water to remove soluble salts and then feed as usual. 
Last year all our garden greenhouse tomatoes were affected by blossom end rot which is supposed to be caused by irregular watering. However, the tomatoes in the plot greenhouse were fine, in spite of less regular watering, than those in the garden greenhouse.
What I draw from all this is that when plants are being stressed in some way we can only try to make an educated guess as to the reason.

Blossom end rot is caused by a calcium deficiency. Irregular watering is blamed as this can cause the plant to be unable to access all the available calcium. However, could it be that the compost is sometimes lacking in calcium which as a result causes blossom end rot.
Interestingly the left over tomatoes growing in the plot cold frame and planted directly in the ground are showing no signs of a problem even though the plants were not exactly prize specimens when planted.

After years of growing tomatoes etc. with few problems why suddenly is it proving to be a challenge? I'm wondering whether a problem with today's composts are causing the plants to be stressed and consequently the symptoms are being attributed to something we are doing wrong.

Professional growers are likely to create their own potting mixes and probably don't struggle with sub-standard growing media but for most of us this just isn't an option.

I am concerned that the ingredients used in compost as well as producing a extremely variable product could also introduce contaminants as Mark has experienced this year.

I'd be interested to hear of any problems anyone else has experienced when using commercial composts. 



35 comments:

  1. Sue, I am more than ever convinced that the commercial composts we buy are the cause of all these problems. Whenever I visit the local Council re-cycling area I see what sort of rubbish goes into the green waste skip, and I know that many commercial composts have about 50% recycled material in them. A lot of the stuff that people take to the tip is the stuff which they KNOW is diseased (aka "sub-optimal"?) and therefore don't want to put in their own home compost bins. And of course some of it is lawn clippings with weedkiller on them! My tomato plants often get the mottled leaves that are shown in one of your photos. If it really is a symptom of magnesium deficiency it doesn't say much for the "Tomorite" plant-food I use so religiously.

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    1. It's reliance on green water that I find worrying, Mark, We use Tomorite too. I wonder if something is affecting the plant roots and stopping them absorbing nutrients

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    2. I meant green waste of course

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    3. I live in Poland so obviously I don't use composts available in the UK, but here in Poland, I've seen once some strange stuff in commercial compost, for example, shredded plastic bags or metal parts. This means people who make it don't really care what goes into the mix.

      Additional, when I put garden or kitchen waste into my own compost bin I pay attention to not to throw citrus peels (because zest is covered in fungicidal sprays which may affect the mixture - unless I wash it thoroughly), I don't add plastic bags, printed magazines, human feces! But hey, we all know what people can do when no one watches. So, compost manufacturers may add many different things into it (such as waste contaminated by sprays, weedkillers), as far as the end product looks as it should be - everything is acceptable, none of us will examine the compost's content in a lab - before using it.

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  2. I know a few people who had some dodgy compost this year. We had some toms that had to be re-potted into different compost as they failed to grow at all and when moved they were fine. I know some people have had to clear their whole greenhouse because of it.

    It's our first year on the plot and we are coming across every problem you can imagine in the first year. We're soldiering on though! just lol x

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    1. Hi Julee, One of the problems is that new gardeners just blame how they are doing things when things fail to grow so it was food that you saw that more experienced people had a problem, Do you know which compost they used? If you'd rather not say here email me (address on sidebar). It would be interesting to know if the problem is more with a particular brand.

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  3. good comment by Mark, the Sungold toms look wonderful

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    1. Mark echoes my thoughts, David

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  4. An interesting post and interesting comments. I avoid the council compost now, I wasn't impressed when I used it when we first moved here five years ago. It was very dry and twiggy, it just didn't feel nutritious or anything like homemade compost. Do you have the option to grow tomatoes directly in the ground? Either inside or out. I've stopped growing them in pots at all now, and I just put them outside in the ground and don't do much to them. It's tough love! I don't get huge crops, and I'm always trying to find which varieties will do the best, but the plants are usually quite healthy, except for the really wet summer. I hope you work out how to avoid these problems for the future.

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    1. This was a very well respected brand, CJ but many now use green waste. We used to make our own bit we need so much. We used to grow tomatoes outdoors but they always got blight. The floor in the garden greenhouse is fully paved but. It could be an option in the plot greenhouse although the ground us very rough and digging space is limited. We have some growing directly in the ground under the cold frame where height is restricted,

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  5. I always thought blossom end rot was caused by magnesium deficiency. And, that epsom salts was the answer to that. Although there are some commercial products available now. I put a half handful of bonemeal in the hole of each tomato plant when potting out plus an organic tomato food around it. Heartbreaking to see your infected tomatoes as they do require a lot of effort to start on, so..such a disappointment Sue. ((

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    1. They are fed regularly, Bren so all the nutrients should be available. All the plants in the same greenhouse are treated in the same way - they only differences are varieties and the growbags. I wonder whether something in the compost is affecting the roots and causing them to be less efficient at taking up the nutrients

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  6. I wouldn't be at all surprised if dodgy compost was at least partly to blame, so frustrating. I've got my greenhouse toms growing directly in the ground this year, and am curious to see if I think they do better than last year's pot and growing option. On the plus side, your sungold are way ahead of mine!

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    1. Unfortunately I wouldn't be surprised either Janet

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  7. To be honest Sue I would be more inclined to lean towards the compost....I will hopefully enlighten you on that subject later in the week!!!!!

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    1. You intrigued me, Tanya. I'm leaning that way too

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  8. Actually with tomatoes is never just one problem. I would bet that your tomatoes suffer both from poor compost and bad venting.
    First as popular as it is growing tomatoes is bags is not a good option. As much as people love it, and they take less space tomato plants always suffer in them. One tomato needs at least 40 liters of well drained soil. Also in normal conditions tomato roots go very deep. That is why tomatoes in bags are great only when everything is "ideal"
    Blossom rot is caused by irregular watering, but again it's also compost and bag problem.
    All it takes is having too little holes for draining and this will happen.
    Try doing this: water your plants, wait 30 minutes and then take some soil in hand. Squeeze it. It should make a little ball. Then take a stick or pen and crush the ball. If the ball falls apart nicely then your drainage is ok. If not then try adding more drainage.
    Composition of compost can be a problem. The more "garbage" they add the worse it it. Well made composts never get lumpy, stinky, or too black.

    This vents are a bit too small for the size of your greenhouse. I know it's hard to open everything since you aren't there all the time. But I don't think that your problem is high temperature(if it were tomatoes would look cooked) it's most likely that there is too much humidity in the air. Tomatoes hate humidity.
    And to answer your doubt no, not all the plants would suffer. Well yes eventually. But first it starts on the ones that are already stressed from some other thing(like bad compost or drainage).

    If it is compost and vent problems you can't do much now but test your drainage and try fertilizing your plants more. But also keep an eye on those lower leaves. From here it's hard to tell but they don't look like they only have magnesium deficiency. It looks like it's a beginning of a disease.

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    1. Le - Thanks for this but itoesn't explain why this is only a problem with some plants and not others that are treated exactly the same - but in different bags - and the fact that we have grown tomatoes in the same way for years and without problems.

      There are grow rings on tip of the growbags to give additional depth and the greenhouse that we are growing them ion is only 8 x 10 - it isn't the larger garden greenhouse, There are three of these vents and automatic roof opening,

      The RHS are the ones that are pointing to magnesium deficiency and say that the plant isn't showing any characteristics of disease pest attack so I am only quoting what the experts tell me but if course it is difficult to tell from a photo. They are basing this on the leaf bit the fruit is a different issue and they say indicates some sort of stress that may be ventilation connected. The problem is more ventilation increases the risk of blight which is a problem. A

      As I say why are these problems occurring now when we have grown tomatoes successfully this way for over 20 years and if it is down to our methods why are some plants suffering and other not.

      When we had blossom end rot it was in the garden greenhouse which is well ventilated and where watering was very regular. The same year there was no rot in the plot greenhouse where plants were more neglected. It also seems that more and more gardeners are complaining about BER and other tomato problems when previously they have had success.

      I just think that the problem we are having recently go beyond what is normal/accepted explanation, The plant is under stress but could this be caused by the compost?

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  9. Here in the US I've found a huge difference in potting mixes. I only use one brand because it always performs and my seedlings grow twice as fast as with other mixes. Of course you can only get it in the NE corner of the US. I just hope they stay in business for a long time because I don't know what I'd do without it.

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    1. The trouble is Daphne that we have thought we have found a good compost and then a rogue batch slips in and spoils everything - even with good named brands.

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  10. Interesting, lots of suggestions! I can only tell you what's happening in my lean-to where I can only grow in pots....in previous years I've mainly used bought multi- purpose compost (peat free) with a bit of added garden soil mixed in. Crops have been ok but I've always had those mottled leaves starting with the lowest, that you have in your pic that RHS say is magnesium deficiency.

    I don't have a car anymore so to save using too much bought-in compost this year, I've used a mix of mainly my own garden & kitchen compost ( usually use this on my two small veggie beds) with a bit of added multi. I've preferred the texture of the mix this year, seems to have better water retention. Lots of egg shells in there too from the kitchen compost. My lean to gets incredibly hot even with the door and vents open. I have noticed a few toms with blossom- end rot, not usually a problem I have too badly but seems more this year, though it seems to be mainly the pear-type varieties, not the round ones. I have also crammed more toms I. This year than previously. The bought- in compost is left over from last year. I've made my own comfrey feed this year that I've used two applications so far, I might increase frequency. Fruit set is good though especially for the cherry type. I try to water evenly but when the temp in the lean to can get so high v quickly it's quite difficult. Some of the pots are sat trays to retain water. I use broken up polystyrene in the bottom of my pots so the roots aren't sat directly in water too much.right, gonna dash to the plot before the next set of storms hit!

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    1. We use loads of bags of compost each year, Lou and just couldn't produce enough home made stuff but it does seem the safest bet.

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    2. Yes it's difficult to make enough. Our back garden is small so it's mainly kitchen waste. Usually I use the compost on the two small veg plots but this year as I was using it for the toms the veg beds only got last years used compost from the toms. I did lay some sheets of newspaper first before tipping out the pots to try and improve water retention and cut down on weeds....saved digging too. The veg beds seem to be doing ok for now! Hope you still a manage to get a good crop of toms.

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  11. It's really interesting lesson. Thanks all for sharing your experiences.

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    1. Just wish it didn't happen, Endah

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  12. Lots of food for thought. We filled raised beds with The Council's "soil improver" early this year which was mixed a bit with some soil. Results have been great this, especially for carrots and peas. Is this because of the growing medium, the weather or something else we have no idea about? All three I guess.

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    1. I think the problem with green waste is in the inconsistency, Lee. maybe most of the time it is fine but every so often something gets into the batch that causes problem. Also mixing with soil will add naturally occurring nutrients that the green waste could be lacking. Selling something as a soil improver seems to imply it is meant to improve texture rather than it is a growing medium too.

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  13. I thought you were growing Tigerellas from your title. It's hard to believe that the black tomatoes you show would be the result of poor ventilation, especially as other plants are performing well. I'm more inclined to believe it's down to bad compost which I've had my own issues with this year. It's becoming more and more common for people to have problems with compost, I wonder how we can overcome it.

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    1. I really don;t know, Jo. Professionals will make all their own compost and we mere amateurs don't have the same influence.

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  14. I find composts are certainly poorer now, so many have added bark and unless you spend an arm and a leg on the expensive stuff you are stuck with the cheaper ones. I have three composting bins now which take ages but I'm hoping to have compost next spring. You would need to make tons of the stuff with such a large plot so yes a problem indeed. Shame about the tomatoes, I hope you still get a good crop.xxx

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  15. Good luck. I hope you can find the causes of your problem. Tomato growing seems to be much more complex in the UK than in North America.

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  16. Why don't you make up your own grow bags ( or much better use very large plastic pots) with allotment soil mixed with well decayed garden compost and slow release fertiliser. It will be much better than some of the substandard stuff offered these days. I will be blogging about this in ten days time!

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    1. Partly we need more than we can create .

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