Borer Resistance??

Since big Pumpkins are selected only for size and many growers make
every effort to save the plants which insects and diseases are trying to
kill, one expects AG to continually lose resistance to pests. That is
not entirely true because a sick plant will not produce a large fruit. 
  I have not heard many reports of borer in the prime Canadian big
pumkins region. Do you have Squash Vine Borer (SVB) there? If not, that
may be the reason AG is so susceptible to vine borers because most of
our seed traces back to the big pumpkins country. 
  I have been around pumpkins on the farm for 60 years and never given
much thought to SVB. I do not recall ever seeing a field pumpkin die of
SVB--all without any sprays. I was aware of SVB because some squash
vines had frass and some died.
  This year, I have not used any sprays, fertilizer, or water. Our
drought continues. Out of 100 plants a few are still alive and now with
70 nite 87 day temps, I am getting some fruit set, but only on Welty
lines and Armstrong 301.
  If you visited the Illinois College SVB page I wrote about 10 days
ago, you found they ranked the SVB resistance of cucurbit cultivars into
5 levels of resistance. AG was not listed. Actually there is no such
thing as an AG cultivar because everyone has added or substracted
alleles as he choose or luck (genetic drift) choose.  
  Weigh off committees in SVB country might consider awarding prizes or
Letters of Merit to pumpkins, independent of size, which have special
merit such as SVB resistance or other important traits so that we can
retain important genes. Since we don't know the number of female SVB
moths in each field awarding such citations of merit may not be
possible. 
  I planted 120 (approx) seeds from a dozen fruit and borer killed 100.
A half dozen of the survivors still have a chance of producing fruit. So
far my crosses have been designed to give info on fruit color, air tube,
and tan seed color. I will also make crosses among those which had the
best SVB resistance. 
  Next year, it would not be too difficult for me to plant 200 seeds one
foot apart at the best time to get heavy SVB infestations and then cull
plants weakened by the borer. 
  While some of my plants show no definite SVB, I suspect every plant
may be infected. If so, the good growth of some vines might be due to
some resistance, but it could be chance (no eggs on a plant) or
accidental IPM. 
  I would like to hear your comments on this accidental IPM. While I
planted every seed the same day and tried to give each seed an equal
chance, the best looking plants went into the best garden row. Perhaps
their size (first row into the garden) is the reason the best SVB
resistance plants are in that first row. 
  I began the plants in pots some pots were only 2.25 inch square. Since
I had no garden space for half the plants, the left over plants, still
in 2-inch pots, had many flowers per plant before dying by SVB. I am
sure the plants which died of SVB in the garden were infected by SVB
while still in the pots. This means we can select for SVB resistance in
2-inch pots (18 of the pots per  tray). That is 10 plants per square
foot. Therefore, I could have tested 1600 seedlings for borer resistance
on the three plant tables which I did not use this spring.
  During 1999, if you live in SVB country, monitor your plants for
possible borer resistance and test the seeds in 2000 or send seeds to
me.   
-- 
Harold Eddleman Ph.D. Microbiology/genetics   i*@disknet.com 
Location: Palmyra IN USA; 36 kilometers west of Louisville, Kentucky
http://www.disknet.com/indiana_biolab = Agriculture, science projects



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