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What could have caused the damage in some of the leafs of this pothos? Fungus? Drought? Pest?

Factors:

  • It appeared suddenly, at the end of winter time, beginning of spring
  • It is an indoor plant, and the windows have been closed for several months, since it is winter.
  • It is not over a heating vent
  • It is not directly exposed to sunlight
  • It has not been treated with any chemical
  • There was a plant in the same room infested with white flies (removed now), but there are no signs of white flies in this plant.
  • There was a plant in the same room infested with fruit flies (removed now), but there are no signs of fruit flies in this plant.
  • Not all the leafs are affected, only 5% of them. And not even in the same stem.
  • A sister plant that lives besides this one has started to show the same damage (three leafs).
  • Notice the row of little holes in one of them.
  • I could not see any pest or eggs on the backside of the leafs, using a magnifier.

Thanks in advance!

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cockypup
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  • What plant was infested with fruit flies? That sounds rather unusual. Fruit is usually infested with fruit flies, starting with bananas and citrus, but they go after pretty much any fruit once you have them. Are you sure they weren't just mold flies or soil flies? I get those when I bring my potted plants in for the winter. They come in on some organic potting mixtures. They are innocuous though pesky having them flying around. – Escoce Mar 28 '16 at 18:30
  • @Escoce They where in an amaryllis bulb. Mostly in the bulb, but then they started infesting the soil. You might be right. They might have been soil gnats. – cockypup Mar 28 '16 at 18:50

3 Answers3

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The leaf with the line of holes in it shows signs of mechanical damage as Escoce suggests.

The other damage is strongly suggestive of fungus/virus/bacteria brought on by over watering. Identification is suggested by:

  • sunken lesions
  • irregular areas of dead tissue surrounded by dying tissue surrounded by a thin line
  • no signs of insect eggs/frass/adults

Plants co exist with a multitude of other organisms in the soil and their tissues. When a stress is put on the plant like lower light and too much water these organisms can get out of hand and multiply to cause the damage you see.

Increase the light, decrease the amount of water and the plant will outgrow the problem. In the spring trimming the roots and re-potting with fresh soil may be helpful.

kevinskio
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  • I think your answer is the most complete do far. Small comment: watering of this plant is actually scarce (out of negligence). Would that change your take on it? – cockypup Mar 29 '16 at 03:05
  • Those symptoms are consistent with fungal/virus/bacteria. Sitting in a saucer of water for a long time can cause this as well – kevinskio Mar 29 '16 at 09:49
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I am going to take a stab at this one. I don't think this is pest induced, but rather the longer term effects of mechanical damage. A leaf getting folded, brushed up against too many times, or the slightest of breezes making the leave rub against something else. Being the end of winter, there hasn't been much new growth and this tropical plant has just been maintaining itself, and these leaves are now simply just too old and weak to push off the effects of having been handled in some way or fashion over the last several cold months.

Escoce
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  • Thanks! There is no much action around this plant to justify mechanical damage though. Also, it had mot changed its spot or being handled differently in a year and a half. Would that change your point of view? – cockypup Mar 29 '16 at 03:08
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I agree it may be mechanical damage, but it may well also be the leaf coming to the end of its life. Especially if there are only a few on the plant, and they look as though they are mature and not juvenile.

  • Thanks! It had never behaved that way though. Leafs usually yellow and wither evenly. Would that change your take on it? – cockypup Mar 29 '16 at 03:10
  • I haven't studied leaves withering to be honest. I did have one of these plants many years ago, the older leaves occasionally became yellow and dropped off in a similar way I think to yours. It didn't stop the growing tip from continuing to grow with new leaves. When it became too leggy, I chopped the plant up into smaller bits, rooted the new cuttings and started it off again. –  Mar 29 '16 at 06:38