I have one courgette plant in my bed and it seems to work well.

We just had 2 super hot days (35 C) and I just saw the the stem (which has become really dark recently) has split open very close to where the stem is coming out of the ground. It must have happened either last night (slug damage?) or during the day (heat?).

The plant does not show any negative signs as I would expect from such a hungry species even only after a short time.

Is there anything I can/need to do avoid problems?

What could have caused this?

EDIT: Added some pictures. Click to zoom in.

  • How is the plant doing now? How did you decide to treat it?
    – J. Musser
    Jul 28, 2014 at 6:01
  • Doing well, thanks for asking. It seems you are right, the stress was making it split. I did nothing. It seems even that the stems has thickened.
    – Patrick B.
    Jul 28, 2014 at 8:00
  • The stem thickening is callous material, which is a good sign of recovery.
    – J. Musser
    Jul 29, 2014 at 21:12

2 Answers 2


If the stem has softened, and there is a small amount of sawdust-like frass by the split, you have squash vine borer. These pests are the larvae of a moth, and feed on the inside of the zucchini stem by the base of the plant. To control, slit the stem open carefully along the main stem until you locate the worm (it is usually not far from the slit it made). Extract and destroy the worm.

If that isn't the case, then it is most likely caused by too much water. Squash plants crack sometimes, right after a heavy rain. This can't really be avoided, but watch for disease in the slit until it callouses.

Another way that a bush-type squash (because of the thicker stems) can crack, is rotating the stem to point another direction. This stresses the stem base, and it may crack. To avoid this, try not to move the stem.


From the picture, this looks like tension splitting, where the stem has a high enough tension in itself to split open. It shouldn't affect growth/production. This isn't a big deal concerning plant health, and you can mound soil around the stem if you want. Do not try to fix with wire, because this will not really help, but may damage the stem itself. Also, this will only happen when the stem 'ripens', or hardens, which sounds like what your plant has done. The stem hardens from the base out, and becomes darker in color - like you've described.

  • Now that it is day I can add a picture.. but I haven't seen any sawdust. And the stem is still really hard at this point.
    – Patrick B.
    Jul 19, 2014 at 6:33
  • @PatrickB. I saw the pic. Not squash vine borer. My best guess is stem tension splitting, which happens when the stem becomes hardened, and the heat could have helped, by dehydrating the stem somewhat, causing just enough tension to cause the split. See edited answer.
    – J. Musser
    Jul 20, 2014 at 0:58

This can happen if the plant experiences more extreme conditions like if it suddenly takes in a lot of water. If the plant seems otherwise unaffected then you probably don't need to worry. Some people will pile soil around the split area or provide extra support for the plant if you think it's been weakened by the split.

  • The only thing I'm afraid of is the wind. I assume that the stem is weak now, I will fix it with some wire.
    – Patrick B.
    Jul 19, 2014 at 6:34
  • After seeing the pictures I would agree about the stem being weak. It's interesting that it seems to have a small secondary split; I hope that it doesn't get worse. Good luck!
    – Alpar
    Jul 19, 2014 at 16:38

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