pests

[P.Bruggeman]

-----Oorspronkelijk bericht-----
Van: Arisaema Enthusiast Group (AEG) Discussion List (and other hardy
Aroids) [mailto:ARISAEMA-L at NIC.SURFNET.NL]Namens M.Hachadourian
Verzonden: zondag 21 november 1999 17:18
Aan: ARISAEMA-L at NIC.SURFNET.NL
Onderwerp: pests

Marc,

I have had the same problem with some of my Arisaema and my guess is that
they are the larvae of the little flies you find in some peat-based
composts. I have the feeling that they start to attack the tubers from
mid-season on (june/july). When left unnoticed they can damage a tuber that
much that the tuber dies. The species that were affected in my collection
were A. limbatum, A.thunbergii ssp. thunbergii and A. concinnum. The species
from the A. candidissimum, A. fargesii, A. franchetianum group seem far less
susceptable. They also attack Pinellia and I have lost a potfull of P.
pedatisecta. I recognize affected tubers by a "corky" skin. I know that a
well-known nursery in Wales avoids using peat-based compost with Arisaema
seedlings for the very same reason. I have no idea how to control them but
using high-quality, sterilized compost seems to be the best choice or switch
to loam-based compost. There must be a chemical way to control them (who has
any idea?) but I prefer to avoid the use of chemicals. It is probably a pest
that occurs in potcultivation only. These flies are my best quess but at
least you know you're not the only one with this problem.

P.Bruggeman
Holland