Tomato problems:
tomato leaves are turning yellow
and stems are dying off

by Mandy S.
(North Queensland, Australia)

Dear Tomato Dirt,
Can you help please? The leaves on my tomato plant are yellowing and the stems are falling off. Am I over-watering? Do they have blight? I really appreciate your help.
Thank you,
Mandy

Dear Mandy,

Sorry about your tomatoes! (We've been there.) Yellowing leaves and dying stems are symptoms of several problems. But keep in mind that they rarely appear alone. Usually, your tomatoes give you another clue to diagnose the problem. Study your plants carefully. Use this checklist to help figure out which situation fits you.

• Over-watering or under-watering. If your season has been especially wet and cool, your tomatoes may be "drowning." Water can clog air pockets in the soil and prevent plants from getting needed air. On the other hand, if you're in a heat wave with excessive temperatures, your plants could be over-stressed and under-watered, which could cause them to drop leaves. Make sure plants are getting 1-3 inches of water a week - on the high end of that if it's hot and on the low end if it's cool.
  
• Early blight or Septoria leaf spot. Yellowing leaves are a symptom for both diseases. To tell the difference, check to see if there are spots on the leaves. Early blight exhibits dark concentric circles on leaves and stems. Septoria leaf spot presents small dark spots on the lower leaves. Read more about different kinds of tomato blight and how to tell them apart.
  
• Tomato wilts. Fusarium wilt and verticillium wilt also exhibit yellowed leaves. Fusarium often just affects one side of the plant. Verticillium encircles the plant, but the yellowed pattern on leaves is V-shaped.
  
• Curly top virus. Infected plants turn yellow and stop growing.
  
• Pests. Aphids, whiteflies, flea beetles, tomato hornworm and tobacco hornworm, and psyllids attack tomato plants and leave holes, dew, or chewing injuries to plants -- in addition to yellowed leaves. Check undersides of leaves and along stems for pests!
  
  Most tomato problems are treatable once you identify the source. Track rain and watering patterns (to see if it's a watering issue). Study the yellowing pattern in the leaves (to see if it's caused by a disease). Look for other additional damage (to see if it's caused by a pest).
  
  Good luck!
  Your friends at Tomato Dirt