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I'm new to gardening and this is my first real try. I've grown some cherry and beefsteak tomato plants (and other veges) from seedlings and have had them growing for a month or so.

Some of my tomato plants lower leaves are dying off and they have tiny black spots around the leaves before they seem to go yellow and die off. The new leaves at the top look green with no issues, however about midway up on some plants these black spots are showing up. Worse down the bottom. The fact that it's climbing has me thinking it might be a fungus from some brief research, however, the pictures of the fungus don't really look like mine at all. Some of my other plants have similar symptoms but not exactly the same.

So I started them as seedlings a month or so ago. We planted them in deep pots sitting directly on grass (maybe drainage problem?) using bagged potting mix from the hardware store (bunnings). I started them in direct sunlight in Townsville Australia where the temperature can get up to 31C/87F. I was watering them once or twice a day with a sprinkler for about half-hour to an hour. All my plants weren't growing too good and I suspected that it might have been too hot for them and that I was overwatering. So 3 weeks or so ago, I moved them under a marquee covered with insect netting (to prevent cats from digging as well as light shade). I also stopped watering them so much (every 2 days once a day). They improved very quickly and grew quite a lot. Looking very healthy. I installed drip irrigation about a week ago and have been watering them with that every 2 days but for longer (1.5 hours). I've also sprayed some insecticide on all my plants a few days ago after finding lots of ants and a caterpillar. It's over these last few days that I've noticed these black spots on a lot of my plants. Mainly my tomato plants.

I'm not sure about what is causing the yellow leaves, black spots and dying of some of my plants. My suspicions are:

  1. The insecticide might be causing issues as I've only noticed issues after using it
  2. I'm overwatering them.
  3. They are not getting enough drainage in pots sitting directly on grass/dirt
  4. I have a fungus that is killing my plants

Here is an imgur link of more pictures containing:

  1. The insecticide I used.
  2. Various images of healthly and unhealthy parts of my tomato plants
  3. Other plants that have similar issues in my garden
  4. Image of how shaded the area is
  5. Pots used

https://i.stack.imgur.com/rDlj4.jpg

enter image description here

Caleb Macdonald Black
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  • This looks like a deficiency of some type to me. How are you fertilizing the soil? – Evil Elf Apr 22 '20 at 10:12
  • @EvilElf I haven't fertilized my soil. I assumed the potting mix would contain everything I need. My potting mix was fairly cheap, however. Maybe I could test the soil? – Caleb Macdonald Black Apr 22 '20 at 11:09
  • Not all potting mix has nutrients in them. Can you check the bag? – Evil Elf Apr 23 '20 at 11:55
  • I just viewed the photos. One of those plants looks like it may have septoria leafspot or blight starting. I have found that fungus splashing up onto the leaves provide me major trouble. Once I started mulching the soil with grass clippings, all my problems went away. – Evil Elf Apr 23 '20 at 11:58
  • @EvilElf It doesn't say much on the bag. Nothing about nutrients or anything. The soil looked pretty good though. Which photo looks like it has septoria leafspot or blight? Also, I drilled a hole in the bottom of my pot and put my moisture meter in there. It was extremely wet and the soil came out quite muddy. I've raised all the pots off the dirt today and after about 6 hours or so the moisture has already gone down quite a bit. I've also cut off all the yellow leaves. The green leaves with the black spots I've kept though until I can identify what it is. – Caleb Macdonald Black Apr 23 '20 at 13:27
  • Over water, pH off, all sorts of things can wreck havoc. Any time you see legions on lower leaves that die off and then it goes upwards, I would suspect fungus or disease. – Evil Elf Apr 23 '20 at 17:34

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