I have several tomato plants although the fruit developed beautifully, all of a sudden Some of the branches turned dark, leaves died and dropped off and some of the fruit turned brown near the stem and fell off the plant. What can cause this. The plant is otherwise healthy with lots of fruit but the problem is expanding to all the plants.
Thank you for your question for Toronto Master Gardeners.
By your description, this sounds like quickly spreading late tomato blight. Unfortunately, very little can be done to help this year’s crop.
You are likely doing some or most of these steps. In the case of blight, prevention is the key to managing the disease and includes:
- Growing your own tomatoes from blight resistant seed varieties as noted in seed catalogues
- Choosing healthy transplants of blight resistant varieties
- Remove weeds of the solanaceous family, e.g. nightshade, jimsonweed, etc.
- Provide good air circulation through planting distance, staking and thinning/removal of lower leaves
- Remove diseased plants, place in bags and discard in garbage
- Do not compost diseased plants
For more information, please see the following:
https://www.torontomastergardeners.ca/askagardener/late-tomato-blight/
https://ag.umass.edu/home-lawn-garden/fact-sheets/late-blight-on-tomatoes-potatoes