Bumps on tomato stems start as hundreds of tiny hairs up and down the stalk. Hairs can turn into roots when buried underground. Above ground, they form tiny nubs or nodules, also called root initials, adventitious roots, or tomato stem primordial. They are the earliest stage of development of a tomato’s roots.
Most of the time, bumps are not harmful to tomato plants and are considered normal.
Root initials emerge on a tomato stem as a result of stress – most often when there’s a limit or blockage in the stem’s vascular flow.
Specifically, a hormone named auxin in branch tips sends a signal to the plant’s roots when it’s blocked in the branch.
If there’s a blockage and the hormone can’t flow freely, it accumulates in the stem.
Nodules or bumps emerge. The blockage can occur anywhere on the stem.
Blockages are caused by a number of things:
Often the blockage is water-related. A tomato plant’s roots need air as much as they need water. Over-watering or excess rain (including poor drainage) chokes them. The plant compensates by trying to develop more roots out through the stem – hence the root initials.
Root initials can be the same color as the stem. They may also be white or turn to brown.
If you see overgrown root initials on your plants, also check the leaves at the tops and the branch ends. Are they curled or stunted? That can indicate exposure to an herbicide.
Herbicide effects mimic the plant hormone auxin and can also cause abnormal stem growth and leaf distortion.
If your tomato patch is near your yard or a neighbor’s, perhaps a weed-and-feed product, weed control, or other herbicide was applied and drifted. Mist often affects tomato plants.
Root initials may not be attractive, but they do not harm plants.
Occasionally, root initials can be a sign of other problems, so keep a close check on your plants. Look for signs of –
More Tomato Problems
Other problems on tomato stems ...
Problems on tomato leaves ...
Problems on tomato fruit ...
Problems from tomato diseases
Different kinds of tomato blight and how to tell them apart ...
How to identify and treat early blight ...
How to identify and treat late blight ...
How to identify and treat Septoria leaf spot ...
Tomato pests
Tomato hornworm: how to identify and control it ...
Pests that attack tomatoes in containers ...
Stink bugs: how to identify and control them on tomato plants...
Tomato worms - cutworms: how to keep them away ...
Problems from growing conditions
Blossom end rot: how to identify, treat, and prevent it ...
15 ways to prevent blossom end rot in tomatoes ...
Why a tomato cracks and what to do about it ...
Tomato sunscald: why too much sun is hazardous to tomatoes...
Help Your Tomatoes Set Fruit with These Tips ...
Tomato Problems: how to identify and prevent them...
Return from Bumps on Tomato Stems to Tomato Dirt home
As an Amazon Associate and Rakuten Advertising affiliate I earn from qualifying purchases.
SHARE THIS PAGE:
FREE! 10 Must-Know Tomato Growing Tips: 20-page guide
Get yours here:
New! Comments
Have your say about what you just read! Leave a comment in the box below.