Subscriber
Alert
This is the first issue of Aphid Alert 2001. This
newsletter is intended to alert Minnesota and North Dakota seed
potato producers to flight activity by aphid species that are
known to be potential vectors of potato viruses. The
trapping network has resumed operation and we will soon be
reporting results weekly on the WWW, by e-mail to subscribers,
and by surface mail to all Minnesota and North Dakota seed
potato growers. To become an e-mail subscriber send us an
e-mail message with the word "subscribe"
in subject line. We
have taken the liberty of adding many names to our e-mail subscriber
list. If you have no interest in receiving this newsletter
by e-mail please reply with the word "unsubscribe" in the subject
line. Some e-mail subscribers may not wish to
receive messages containing graphics, if so reply with the the words "no graphics"
in the subject line. |
| Background
The 1998-2001 Aphid Alert
project has much in common with a 1992-1994 research project of
the same name. During that time, our focus was on vectors
of PVY. In the mid 1980s, Minnesota and North Dakota
experienced a persistent PVY epidemic that grew increasing
severe each year, until ended in 1992 by the almost complete
absence of potential PVY vectors throughout the region.
Data from 1991-1994, provide useful baselines we can compare
with present vector abundance and phenologies to identify
possible differences in that may account for present severe
problems with both PVY and PLRV.
|
 |
Figure: The proportion of
Minnesota seed potato acreage rejected for certification because
of excess prevalence of virus infection increased from 6% in
1993 to 57% in 1998 and 1999. In 2000, the situation was
marginally better with 46% of acreage rejected. |
 |
Figure: The recent crisis
in the Minnesota seed industry has been caused by both PLRV and
PVY. Decrease in PLRV in 2000 compared to 1998 and 1999 is
presumed to reflect the reduced abundance of green peach aphid
in 2000. Both PLRV and PVY remained high probably
reflecting the large amount of virus inoculum that must yet be
flushed from the potato production system. |
 |
Figure: Trap locations in
Aphid Alert network in 2000. |
 |
Figure: In 1998 and 1999,
green peach aphid, the most important vector of PLRV, was much
more abundant than it had been in 1992-1994. This increase
may be related to the great expansion of canola acreage that has
occurred in the region since the earlier study. Canola can
produce large populations of green peach aphid that take wing in
mid-summer as the canola matures. |
|
Figure: PVY can be
transmitted by many different aphid species. Some of these
vectors are very inefficient compared to green peach aphid, but
often they are much more abundant. The complex of aphid
species associated with small grains were implicated as
important PVY vectors in 1992-1994. |