Friday, June 15, 2012

Diagnosis: Malnutrition?

For those who haven't been keeping up with my posts, my tomatoes have been "under the weather".  Initially I thought this was due to a fungus of some type.  After some further research I'm not so sure any more.  I won't be able to take one to the Extension Service booth this weekend because I have other things to do that day. 

Looking into tomato diseases I found that most of the fungal infections have yellowing of the tissues surrounding the brown/gray/darkened spots.  My tomatoes don't have any yellowing until the whole branch has withered and is falling off.

Since they were clean seed, planted in clean soil-less mix, in clean pots, and were inside the whole time I've kind of ruled out any soil or pest-borne diseases. 

But! I did find out something I didn't know, probably because I've never started my own tomato seeds before and had them survive this long.  Purpling of the leaves is an indicator of phosphorus deficiency.  This makes sense, they have been in those little pots full of seedling mix forever, and only had fish emulsion for nutrition (high nitrogen, barely any phosphorus or potassium).  So if they are purple because of lack of phosphorus, maybe their are deficient in other things too... it turns out that potassium deficiency causes browning of the leaf margins and curling of the leaves.  In fact, many nutritional deficiencies cause some type of discoloration and leaf curling.

Sweet Million 4 days ago
So I gave each a scoop of compost to top off their pots, and spritzed with compost tea as planned.  Even if it really is a fungal disease causing the leaf browning and curling, improving the plants' overall health should help with that.  If it's not a fungus, the compost tea foliar spray will still provide fast nutrition.

Sweet Million today

One of the things that tipped me off was that the Sweet Million was transplanted just a few days ago and is now looking much healthier.

It's difficult to tell in the picture, but the earlier shot had a purplish stem and leaf color to it.  It's very obvious that it's a bright, healthy green now; though the leaves that had already curled are no better, the rest look great.


  1. Purpling can also happen if tomatoes are set out when it is cooler than they like. They outgrow it when things warm up. Cool temps, however, don't usually cause the leaves to turn brown. Hope they perk up.

    1. That's true. I should have mentioned it. I knew that wasn't the case here because these had been inside the house the whole time. But good point.