Greenhouse Tomato Yellow leaves

[Descant Rules]

I have three tomato plants in a greenhouse. They are all developing yellow leaves at the top and have leaves with brown spots at the bottom. Also a lot of the flower stems are breaking about 4mm from the flower and dropping off.
They have produced tomatos so far and have others developing.
Any ideas what the disease is and is there a cure.
Help please

[SueA]

Hi Descant Rules & welcome to the vine. The first thing I would think of is blight but as your toms are indoors I wouldn't think that was likely.It could be something like tomato leaf mould which is caused by warm humid night time conditions which is a possibility with the warm wet weather we've been having.Are there any signs of a brownish mould under the leaves? If it looks like that I'd ventilate the greenhouse well, remove the worst affected leaves & spray your toms with either a chemical or organic fungicide spray. Make sure you keep the plants well fed & watered & hope for the best. Good luck!

[Alice]

Hello Descant Rules, your tomatoes sound as if they could be suffering from a magnesium deficiency. If this is the case they will recover if you spray them with magnesium sulphate (Epsom salts). You can buy it in the chemist. Dissolve 2 teaspoons in a pint of water and spray them well every day for a week. If this is the problem you will see results quickly. Even the yellow leaves will green up. Good luck.

[bramble]

Alice, I have to say I am having the same problem with my chilli peppers this year as well. I'm not sure what the problem is. I did water Epsom Salts into the soil but did'nt see any difference. I am also experiencing quite a lot of blossom drop on both the peppers and tomatoes. I put it down to the queer wet and humid weather we've been having. If anyone else knows different I would be pleased to hear.

[eskymo]

sounds like magnesium deficiency to me. I managed to get a big box of Epsom Salts from a garden centre and you can either dissolve it in water and and water the plants with it or do as Alice suggest and spray your plants.

I get this every year...not sure why...is it due to over watering?

I've been spraying mine every day with ES and my plants certainly do look less yellow and healthier. Not sure the yellowness ever goes away completely - well I've never managed that.

[bramble]

Eskymo, I'll spray them instead of watering the ES in. Also, i think I might not have been using enough so will use more and see how I get on.

[Alice]

Hello Bramble and Eskymo, I have found where the problem is magnesium deficiency that spraying with Epsom salts produces instant and visible results. If no results are seen then maybe that's not the problem. It's back to blaming the weather - so humid. I do hope things will work out for you.

[SimonCole]

I disagree with the above posts and believe that the problem is lack of nitrogen. This causes the typical yellow discoloration you described. The brown spots are very common in older leaves that do not get enough potassium, but this is mainly a factor of old growth. I recommend a liquid fertiliser. Most tomato fertilisers also contain extra magnesium in case you were worried.

[eskymo]

does comfrey feed contain the right stuff for tomatoes...I feed with comfrey feed once a week and spray with epsom salts every day, but still have yellowing leaves...they start at the bottom and work their way up and that's definitely signs of magnesium deficiency.

[BigstU]

I find the easiest way to spot the difference between and mg def and an N def, is with mg you get the yellowing of the lower leaves, but the veins of the leaf remain green. With the N def a more uniformed yellowing of the lower leaves is seen, including the veins. Both work there way up the plant as they worsen, it works this way as N and mg are mobile elements and can be moved around the plant.
Foliar treatment is quickest as adding lots of epsom to pots can upset nutrient uptake by the roots and could cause lockout of certain feeds, leading to further probs.

[bramble]

I am watering with Westland tomato plant food every week and also adding Epsom Salts but the problem is getting steadily worse. My tomatoes are in half growbags. I cut the bags in half, emptied out the soil, mixed with perlite and refilled them. I have them standing lenth ways rather than flat. There is about 17 litres of soil in each one. i have also done this with some of my peppers. I look after them really well but just can't track down the proble. They are in a greenhouse/