Peter Dillon posed an interesting and difficult question:

> Observing the growth rate that appears to have occurred in certain areas of
France this year,
> I pose this for thought:

> This year sunflowers are flowering up to 3 weeks in advance of normal - growth
rates allowing flower
> formation to occur early.  Therefore, if a systemic product is deemed to be
active for 60 days,
> but now flowering is occurring in a period that is shorter than the 60 days -
what is the consequence
> on "the label" for the insecticide? - presuming that the active material
should not be present during
> the flowering period!

That's a tough one.  I'm not qualified to say exactly how a systemic insecticide
is metabolized by a plant, or build a model for long this might take under
different weather conditions.  I can point out that available information
clearly indicates that it varies with application method.  I don't even
know if a "treated" seed would be affected by factors like heavier rainfall,
which is known to affect ground treatments.

I think that what data exists is not going to be useful to answer this question.
The existing data talks about how long the "treatment" is effective in killing
pest insects, which clearly MUST be a much higher "dose" than a "dose" that
could
be sub-lethal but debilitating to a bee.



One thing I do know is that the early blooms are NOT due to "global warming".
Not just yet, anyway.  :)

Any change caused by global warming sufficient to change average blooming
dates of plants by three weeks in temperate zones (like France, where Peter
lives) would come AFTER we see icecaps melt, the ocean level rise, and the
offering of high-priced beachfront property in places that were never
"beachfront" before.

A "few degrees warmer" won't add up to much in the early spring after last
frost, which can be verified by anyone will to calculate the "degree days"
from last frost to bloom, but the same "few degrees" can melt polar icecaps.

How many degrees might melt the icecaps?  The number "2" comes up a lot.
Maybe it is 4, maybe 6. I don't think anyone really knows for sure, but
it is certainly less than 10.

So let's imagine everything is 2 degrees warmer. A mere 2 degrees would be
swamped out by plain old "weather variation" in regard to bloom periods.
Here's a good example:

http://www.entomology.cornell.edu/Extension/Woodys/GDDtracker.htm

This is a map of New York state, showing the total of "growing degree days"
to date for various automated monitoring stations around the state.  As the map
shows, even a small distance can make a difference of nearly 100 degree days

Looking at the average of early spring seasonal temperature changes, a good
rule of thumb is that you will see one degree increase every four days, and
you can model the "typical" spring by assuming that you will have four days
with equal "high" and "low" temperatures, then another four days with a
one-degree increase in both the high and the low, and so on.

Since little or no plant growth happens until you get above 50 F, the impact
in early spring would be only "+2".  After the average low temperature got
above 51 F, then the effect would be "+4" from that point on.

If you think of the graph of daily totals of degree-days to date, and add 2
degrees to all the temperatures, you still have a straight line:

                y = mx + b

...but you are simply adding 2 to "b", which moves the line upwards two notches
on the y axis.

If we take my data for April - July in Virginia (a typical period for "the
blooms"),
and start counting degree days on April 1, you end up with only a few days
difference
in reaching the same total degree-days in each month:

  Traditional         Traditional
  Temps               Temps +2
  ---------------     --------------
  April 30 = 519      April 27 = 511
  May 31 = 1355       May 27 = 1375
  June 30 = 2630      June 25 = 2664
  July 31 = 4120      July 22 = 4133

You can get more difference than the above in sunflower blooms simply by
picking a different hybrid seed, as different strains have different
bud-to-blooming periods.

If you wanted to get the same number of degree-days "three weeks earlier"
by the end of July, you'd need to have 8 degrees warmer highs and lows
for the whole period, which would end up with the following degree-day totals:

  Traditional         Traditional
  Temps               Temps +8
  ---------------     --------------
  April 30 = 519       April 21 = 507
  May 31 = 1355        April 16 = 1349
  June 30 = 2630       Jun 10 = 2595
  July 31 = 4220       July 7 = 4270


Global warming?  Yes it is happening.
But a noticeable impact on bloom dates this year due to global warming?
No way.


                jim (Who sold his beachfront house in Ft. Lauderdale
                 in the 1980s, and moved to the mountains, but
                 still owns land in Live Oak Florida. Why?  Do the
                 math on any global warming scenario you wish to
                 choose, and look at a topo map of Florida.
                 Consider where the "beach" will be.)

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