New Leaf Problem

[Tim DH]

Does anyone recognize this problem? Its new to me!

It is affecting all the plants in one bed (6 different cultivars) They are all grafted plants. Other beds not affected. Lower leaves are yellowing. Higher up, the main/primary leaflet of each leaf turns first, mostly from the tip.

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Any ideas/advice gratefully accepted!!

Tim DH

[bower]

Lower leaves yellowing, usually means there's a shortage of N, and perhaps those low leaves are also not getting much light, so the plant withdraws the nutrients from the lower leaf to feed new growth. It may also be damp in the lower canopy, which is ideal for early blight (Alternaria) to invade, especially if the plant is poaching nutrients from those oldest leaves.
The last two pictures could be early blight. Check for a "ring spot" with a darker line around a lighter center - this would be typical and your last pic does look like it.
OTOH the tip yellowing as seen in the first pic, in upper canopy (which in the greenhouse tends to be warmer and dry) is something I see here and which I've been blaming on mites. Some kind of tiny pest which does best in heat and dryness, which always attacks those upper canopy leaf tips here when it gets sunny and warm.
The pic 3 leaf is notably yellowing from the tips - which is not really typical of Alternaria blight, those spots appear at random placements - so I would suspect a combination problem involving tiny pest plus Early Blight.

[MissS]

@Tim DH It looks to me like you have a bit of Early Blight. As Bower has said eventually you will be seeing some type of halo effect around the spots.

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I would suggest removing the affected leaves and then spraying your plants with a fungicide and a week later with copper as a preventative. Keep alternating between the two. Clean up all plant material as the can live in your soil.

[bower]

When leaf tips are affected I often just pinch off the affected tip, instead of taking the whole leaf.
I figure it simulates herbivory and might stimulate plant defenses.
OTOH I'm not skilled with sprays, but they might work much better.

[Tim DH]

I finally came to the conclusion that the problems in this bed were a combination of insufficient water AND magnesium deficiency!

I think the insufficient water was due to an ant nest setting up in the bed. As part of their work they must have radically improved the drainage! So despite this bed receiving the same amount of water as its sister beds, the plants in this bed were permanently thirsty.

I think the Magnesium deficiency was caused by running out of the liquid fertiliser I’ve been using for the last few years. I couldn’t find a supplier, so I ordered a ‘look alike’ product. The potassium balance in it must be different. (The label on the old container being so worn that I can’t read it!)

Doubling the watering, halving the feed concentration and spraying with Epsom salt sorted everything out, but, sadly, a little late in the season.

[bower]

@Tim DH thanks for posting the solution to your problem.
I do think that extra feeding and TLC seems to help with a variety of tomato leaf issues - I haven't tried the magnesium supplement but I'm taking note your data point in favor.

[rossomendblot]

Ants turn soil to dust and stop it being able to absorb and hold onto water.

Which liquid fertiliser do you use?

Do you have late blight in Yorkshire yet? It's been here for a few weeks now.

[Tim DH]

Hi Rossomendblot,
The new feed is 'Organic Tomato Focus' from Growth Technology.
I've yet to see ANY blight on my tomatoes this year. The plants on the allotment usually get it first since so many of my neighbours there grow spuds. Mind you: All my outdoor varieties are reputed to have some sort of resistance. ... Not that that stopped me having dead plants by this time last year!!

[rossomendblot]

I live near a potato growing area so that's probably why I get it earlier than elsewhere. There's an allotment a couple of hundred metres away, too. I only grow blight resistant hybrids outdoors now; blight still affects the leaves somewhat, but I've not had it get into the fruit yet.