Crinum viruses
Joe Shaw (Tue, 22 Aug 2006 17:13:31 PDT)

Hi Gang,

Two or three years ago there was a nice bit of discussion about Crinum
viruses, here at the PBS. I remember doing some research on the matter and
since that time I've been thinking about Crinum viruses.

In the past few months I have written to multiple colleagues on several
continents, and I'll be writing up that information soon. But the really
amazing thing is that there is almost no scientific information, at least
little published in recent decades. There are 2 possible viruses that might
cause mosaic on Crinum, Hippeastrum Mosaic Virus (HiMV), and Crinum Mosaic
Virus (CriMV). It seems possible that the 2 viruses are very closely
related, or even the same virus, but perhaps not (no data).

No other virus type has been described (ever) for Crinum. Thus,
yellowing-type viruses, or necrotic lesion-causing viruses, etc., have not
been described. Of course, Crinum are not a big "crop" for the
horticultural trade and it is possible that many viruses remain undiscovered
merely because no one has bothered looking. In other words, government
Plant Health Departments, or individual professors, or other researchers,
may choose to research problems that are more immediately related to global
food production, etc.

The 2 viruses that have been mentioned are potyviruses (named after potato
virus Y, a well studied member of the group). Generally, potyviruses are
transmitted by aphids or by "mechanical means." Mechanical transmission
means (to me) that if you use shears to cut one plant (leaves or bulbs), and
the same shears to immediately cut another plant, that transmission may
occur. In contrast, mechanical transmission typically does not happen by
leaf-to-leaf toucing in garden. Thus, leaves from 2 plants that blow around
in the wind, and which may have tearing or rips, don't seem to transmit the
virus to each other.

I hope to put images up soon, which I think are caused by insect damage,
pesticide damage, mosaic viruses, heat stress, fungi, etc.

For my own part, unless I find out about a new type of virus, I assume that
all I have to deal with is a mosaic-causing virus that is transmitted by
cutting tools or aphids (not sure of the species). I have kept a few
possibly-virused plants on one side of my yard, but have kept them
over-treated with systemic insecticide so that (I suppose) any aphid will no
have a chance to infect plants 100-200 feet away.

Additionally, I have placed some possibly virus-infected plants near healthy
plants of different types. I'm waiting for more time to pass, but in the
past 18 months no mosaic symptoms have shown up on the healthy plants next
to plants with mosaic. Sometimes it can take years for virus symptoms to
show up (not often, but sometimes). I think gravepine cuttings imported
from Europe into the USA require a 5+ year quarantine just to "make sure"
they are clean.

Cordially,

Joe
Conroe TX
Rain may be on the way (about time), lots of thunder and lightning, and my
little dog is is hiding from the noise.