Hi Master Gardeners team! I ve had my tomato seedlings since mid march indoors… due to this cold spring we are having, I am hardening them off but looks like many leafs got sun burned, paper like shiny silvery color on them. I read it could be sunburn or excess fertilizer (I did fertilize them) I am wondering what to do as I cant afford to discard them. Should I pinch affected leaves off? Plants are eager to go out to the yard, its been a long time inside.
Thank-you for consulting Toronto Master Gardeners with your question.
While fertilizer can certainly cause the kind of whitening of leaves you have noticed on your tomato plants, the fact that you are in the process of hardening them off and they have just had their first major exposure to sunlight makes sunburn on the leaves a more likely cause of the problem. When you first bring your plants into the sunlight, they should be put in a shady spot for a few days. They should also be protected from any strong winds as this can also cause the leaves to scorch. Ensure that your plants are well watered. Avoid any fertilizer for the first week or two outside.
You can proceed with this approach with your plants. Hopefully, they will have enough unharmed leaves or leaf area to continue to photosynthesize and produce food for your plants. It is better to leave the scorched leaves on the plant unless they wither and become crisp. In this instance you should remove the dead leaf material so that it does not become a magnet for disease. But as long as there is any green on the leaves they are essential to the growth of the plants.
Good luck with your tomato crop!