Need help identifying brown patches on leaves

[Natweb01]

Hi Everyone! I'm brand new to tomato gardening this year and need help identifying an issue I'm having with some leaves on one of my tomato plants. I've looked at lots of pics online but I'm still not sure.

Some of the leaves on one plant are developing brown patches. The patches are quite uniform and they're between the veins on the leaves. Some of the leaves affected are larger, older leaves but some leaves are also smaller, younger leaves.

The plant is otherwise fine, blooming, yielding fruit and producing new shoots.

I'm growing my plants in large pots in my backyard. I live in the Vancouver area of British Columbia so the plants have been rained on a couple of times (very light rain only though; I moved them undercover when it rained hard). Otherwise the weather has been sunny and hot the past couple of weeks.

So far, I'm only seeing this issue on one of my plants.

I've attached a couple of pics.

Any ideas what this is? And if so, how do I fix it?





THANK YOU!!!

~Nat

[SeanInVa]

My first thoughts are a nutrient deficiency - maybe Phosphorus. What does your feeding schedule look like? Are the patches brown, or could they be purple?

[Natweb01]

I haven't actually fed them anything yet. I bought the plants 4 weeks ago and transplanted them into 20 gallon pots, in a mix of 50% organic potting soil and 50% organic fish soil. Should I have fed them something by now?

I was watering them every day for the first week, then felt I was over-watering. And then switched to watering them every second day.

The patches are brownish-purple, but a bit more on the purple side.

Thank you!!!

[dfollett]

phosphorus deficiency. Feed them a high phosphorus fertilizer.

https://extension.umd.edu/hgic/topic...ncy-vegetables

[Natweb01]

Thanks very much for the help!!!