Hello Master Gardeners.
Looking for help in determining what these brown spots are on our tomato plants.
– Backyard garden is in Toronto
– March 21 – Tomato seeds started indoors
– April 30 – Repotted to 3” pots
– May 23 -Transplanted to Greenhouse (Greenhouse does not get full sun all day. In past, tomatoes have done well)
– May 25 – Noticed brown spots on two of the varieties, Cherokee Purple first and then Sweetie. Not on all plants.
– Appears to be first leaves only.
Cheers
Thanks for contacting Toronto Master Gardeners. It appears to be the early onset of a type of leaf spot or some other type of virus. It’s not clear which one it is. For now you might do the following to keep it in check:
• Pick off all the affected leaves and throw them in the garbage.
• Disinfect any tools you have used on the plants before using them with other plants
• Mulch the plants and stake them.
• Ensure there is adequate air circulation between the plants
• Keep the leaves dry by watering the soil and not the leaves.
• Do not save seed from infected plants
For further information on management of leaf spot and prevention please review the following websites:
https://extension.umn.edu/plant-diseases/tomato-leaf-spot-diseases
http://www.missouribotanicalgarden.org/Portals/0/Gardening/Gardening%20Help/Visual%20Guides/Tomato%20Foliage%20Problems.pdf