Sciaridae and nematodes

Nils Hasenbein via pbs
Tue, 16 Mar 2021 07:53:31 PDT
Dear all,

a while ago the group discussed methods preventing root/tuber/bulb 
damage by sciaridae.

During the last years, I have tried to use as much peat-free potting mix 
as possible, and my impression is that all brands I tried are heavily 
infested, likely because the source material is much more yummy for the 
flies than peat. For small batches e.g. for sowing seeds, I sterilize or 
thoroughly dry my potting mix, and use yellow stickers to slow sciarid 
population growth down, which works ok but is a lot of effort during the 
most critical time for me, which is when many pots are indoors during 
winter (Also, those pots which are not hidden away look much better 
without yellow stickers with hundreds of dead flies attached).

Uli mentioned nematodes, which are readily available from (online) 
stores here in Germany (called nemabest, nemaplus and the like). I used 
them before, but last autumn, I was more systematic and I am very happy 
with the results. The treatment has to be timed well to treat all pots 
at the same time, but the dry nematodes keep for some weeks in the 
fridge, and the final solution seems to keep for some days  - the 
instruction leaflet leaves you with the impression that they are very 
fragile, but my experience this last winter suggests they are a bit more 
robust than I assumed.

When most pots were inside, I dissolved the powder in a large watering 
can, and each pot already in the house got a shot, and all pots entering 
the house over the next week or two were treated the same. I still had 
almost half a can left, so a little goes quite a long way. I used the 
leftovers to inoculate the remaining bags of potting mix left outside to 
unknown effect. The reason I report this now is that I just spotted my 
first Sciarid since autumn (in a pot with vegetable seeds sown some 
weeks ago), so I think the method worked extremely well. I can highly 
recommend it.


(in central Germany, where sun, heavy rain and hail take turns and six 
rainbows were spotted during the last two days. Galanthus nivalis are 
dropping their flowers, yellow trumpet Narcissus start flowering in the 
lawn, and the first tulip buds are emerging. In the woods, a lot of Arum 
maculatum are breaking through the dead leaves)

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