REPLY2: [pbs] Narcissus 'Quince'
DaveKarn@aol.com (Thu, 15 Apr 2004 09:45:43 PDT)

In a message dated 14-Apr-04 1:42:34 PM Pacific Daylight Time,
jshields104@insightbb.com writes:

Jim ~

This is a concept rather widely believed. While it may be true in genera
other than Narcissus, I stand by my statement that a plant, once infected with
virus, is best destroyed or kept isolated. I still isolate many narcissus
thinking I would use them for their genetic material. Now, however, I am
questioning even that practice since there is evidence that daffodil viruses can be
seed transmitted. I think it fair to say that all clonally propagated plants
will, sooner or later, contract one (or more) of the viruses known to infect
their genus.

Bear in mind, there is no guarantee that virus spores won't survive any form
of heat treatment only to re-infect when conditions are appropriate (the
propagule must continually be ELSA tested for any degree of certainty). In heat
treatment of Narcissus, at best, all one can hope for is a diminution of
symptomology, not a "cure." I still stand by my belief that once infected, virus in
a plant is incurable. On the other hand, what often happens as a result of
heat treatment is that viral activity is diminished for a year, or two, leading
to healthier appearing plants and to the belief that a cure has taken place.

Heat treatment in the form of a circulating, hot water bath in an insulated
tank kept at 114 deg F (45.6 C) for three hours is the recommended treatment
for the occurrence of the bulb and stem nematode (Ditylenchus sp.), the
absolutely worst event to befall a daffodil (or any tunicate bulb) grower! At this
temperature range, there is a very fine line between curing the infestation and
the death of the bulb! The colloquial name for such treatment is "cooking,"
and for sound reason! I have heard that there exists in Holland a heat
resistant form of this nematode that has (most likely) arisen from sloppy heat
treatment practices over the years. Woe to one who contracts this one!!! Over the
years, the best advice I have heard, has been (and not entirely
tongue-in-cheek) to sell the place and move and start over!!

Formalin (formaldehyde) has long been the recommended additive to the hot
water bath to combat fungus (e.g., fusarium) at the same time. In many places,
this is now a restricted chemical, if even available any longer, even though
this is a naturally occurring substance. There are some newer replacement
chemicals that have come into the marketplace that have been shown effective
against fusarium and the fungi infecting the outer scales of the bulb.

Dave Karnstedt
Cascade Daffodils
Silverton, OR 97381-0237
email: davekarn@AOL.com