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One of my amaryllis bulbs is infected with the narcissus bulb fly : ( It was planted and it started seeing white mould forming around the bulb. I took the bulb out and sure enough it was starting to rot on its side. By pressing on the decayed area I found a maggot.

I know most people recommend discarding the bulb, but I rather try to save it. The damage seems to be mostly on the outside layers, since it is a big bulb. I know most likely the mother planted two eggs on the bulb, though, so there might be another maggot eating away the bulb where I can't see it. So my questions are:

  • Has anyone actually saved an infected bulb? What method was used?
  • If I use the method of soaking the bulb in hot water (43c - 44c) for 40 minutes, do I need to keep the water constantly at that temperature?
  • Can I cut the decayed part of the bulb (mostly on its outside) and plant it again? Wouldn't it rot (like it was doing before) not having its protective layers?
  • I have seen some people slice the bulb completely to get the worm out but I could not find a description of the whole method. How does this method work? Can I plant the halves afterwards?

Thanks in advance.

  • Is this planted inside? Damage to the outer portion of the bulb is not a usual sign of this insect. It burrows into the center and eats this portion. Not sure you really have this pest. – Eric Deloak Dec 3 '15 at 17:35
  • Oh, I did have it. I had it in a jar for half a day until my partner yelled at me and I flushed it : ) – cockypup Dec 4 '15 at 17:02
  • I mean are you sure it's the larvae of the narcissus bulb fly. It could be of nearly any other fly. They will be attracted to a rotting bulb. Oh, and is this bulb in a pot inside (being forced)? – Eric Deloak Dec 4 '15 at 17:05
  • Well, I am not 100% sure but it looked exactly like the larvae of the narcissus bulb fly and its modus operandum was the same. I had larvae in fact in 2 bulbs. One was a small bulblet had been growing for two years. That one had 2 larvae and was completely eaten inside so it was not salvable. – cockypup Dec 4 '15 at 19:14
  • The bigger one had one larva that I could see. The inception point was at the top, which I discovered after removing the rotten/eaten area: I could see a tunnel coming from the top between the leaves and emerging at the bottom, between the roots. Then there was a huge cavity "towards" the side, were the larva was still living and eating towards the centre. These two bulbs spent the summer outside getting some nutrients from the sunlight (and apparently attracting bugs) and they were now inside being forced. – cockypup Dec 4 '15 at 19:14
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I saved a batch of specialty daffodils I had received, as they arrived infected, and I was unable to get a replacement. I decided to go for it and try to save them, instead of getting a refund. Because Daffodil and Amaryllis bulbs are very similar in form, this answer will likely be closely applicable to your situation.

I have the reference guide 'Plant Propagation', by the American Horticultural Society, and I used the method of bulb chipping in that book. I will quote that here:

1. Dig up a healthy bulb when dormant and clean it. Remove any papery outer skin and trim back the roots with a clean, sharp knife without cutting into the basal plate. Cut back the growing tip.

2. Holding the bulb with the basal plate uppermost, cut it into 8-16 similarly sized sections ("chips"), depending on the size of the bulb. Make sure that each chip retains a piece of the basal plate.

3. Soak the chips in a fungicidal solution, made up according to the manufactures instructions, for up to 15 minutes to kill any bacteria or fungal spores. Allow the chips to drain on a rack for about 12 hours.

4. Place the chips in a clear plastic bag containing ten parts vermiculite to one part water. Inflate the bag, then seal and label it. Keep the bag in a dark place at 68°F (20°C). Check the bag periodically and remove any chips that show signs of rot.

5. After about 12 weeks, bulblets should form just above the basal plate. Pot the chips individually in 3in (8cm) pots in free-draining soil-based potting mix. Insert each chip with its basal plate downward and the bulblets covered by about 1/2" (1cm) of soil mix. Leave the scales exposed, they will slowly rot away as the bulblets develop. Grow on in a sheltered position, in conditions appropriate to the individual species.

Note: This guide specifically states using dormant bulbs, but my infected plants were sprouted, and it worked for them too. Just cut the entire top growth off.

Some of the bulbs had no material left that was healthy enough to use, because of how this larva burrows. I had enough, however, that I got a fair survival rate, and in 3 years, they were at blooming size.

picture of bulblet formed in the chip of a daffodil bulb:

enter image description here

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    Amazing. (+1) This clearly explains what I was calling "the slicing method". Thanks a lot! – cockypup Dec 4 '15 at 20:15

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