Topic: early blight on tomatoes?

[earlypea]

Usual question?  I know it's asked over and over, but I really find it hard to identify for certain from information and photos online. 

Here are three photos of two tomato plants.  My OSU Blue was particularly badly affected by this on the lower leaves, but that was end of May onwards and the stems aren't rotten and it's not progressing rapidly like late blight which I have had before on my potatoes.  It's just some lower leaves that are affected on about a third of the plants and the tomato flowers on my Furry Yellow Hog crisped off, which was odd.

(Otherwise, my Arrarat flame and Stupice are going big guns - with whopping toms for the time of year  )

Can anyone say for sure whether this is early blight or something less annoying?

[BarriedaleNick]

Doesn't look like blight to me - Have a look here

http://www.haifa-group.com/knowledge_center/crop_guides/tomato/plant_nutrition/nutrient_deficiency_symptoms/

[Ian Pearson]

I agree that this is not early blight. The fact that it is only on the lower leaves points to mineral deficiency, and this is quite normal, as the plant moves valuable nutrients from leaves that are getting shaded out to those growing in full sunlight. It's probably potash that is in short supply, but it could be a combination of this and others. Some diluted urine or tomato feed will fix it. Long term, it's a matter of building up your soil with more organic matter.

[antipodes]

here in France, once there is good top growth, most people remove the leaves from the first foot of the plant... I admit that I too remove any leaves that are slightly yellowing, and any leaf groups that are too big or too close to the ground. Sometimes a stem can get damaged without you noticing and the whole part will wilt up and die. 
You can tell blight because it attacks the stems really quickly : a tomato has naturally dark or purplish areas at the joints of stems, but when they are blighted, you see brownish blotches on the stems.

[earlypea]

Thanks all for the replies - they put my mind at rest.

The tomatoes did begin to look worse, leaves at top of one went very odd but it looked like classic mineral deficiency.

Having googled a lot it seems early blight is most uncommon in the UK anyhow - it's a North American phenomenon. 

I also read that mineral deficiencies can be caused by overdoing tomato feed, which apparently gives an inbalance of too much nitrogen.

Anyway, seems to me that you're right, there is too little organic matter.

I've been absent from my plot for  3 years and dug in lots of high potash compost, but it was 'double strength' Sheeps' wool compost and it said don't overuse and don't add any other fertilisers.  Seems to me that it wasn't enough organic matter but you can't use more than 1 to 2 (compost to earth ratio).  Normally I use their standard wool compost because that goes so well with my soil, but this new one doesn't work for me.  Seems to me that there is too much nitrogen.  The stems are much thicker than usual and my bush types are much leafier than before.

Anyway, I've pulled a lot of the lower leaves, cleared off the mulch top-dressed with worm castings and some plain old wool compost and put the mulch back on to try and get more humus and moisture into it.  Also gave it one tomato feed.  We'll see how it goes, but actually they're all sprouting toms now and the Arrarat Flame has amazing trusses (3 inch toms).

I think all's well.

Cheers

[petefj]

The yellowing of the leaves in the middle photo would indicate to me that it's magnesium deficiency.  And that is easily cured by watering in a tablespoon full of epsom salts to five litres of water.  Repeat this at first sign of yellowing.  I give this to my tomatoes at the first sign of yellowing leaves.  It seems to do the trick for me.

Peter

[chriscross1966]

Looks like iron or magnesium issue (probably magnesium)... so either Epsom Salts, rose food or chilli food (chillis have issues with magnesium sometimes anyway so a dedicated food will contain it)...