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Re: CULT: Borer control-a new twist

>> > While out today picking up chemicals for the garden, I had a thought
>> > to ask if there was a liquid form of imidacloprid (active ingredient in
>> > Merit). Indeed there is-- a concentrate that can be sprayed directly on
>> > the plants. It is much faster acting than the granular form due to the
>> > application method. It is also supposed to be season-long

I use the granular form of Merit because of the climate/growth patterns 
in my garden.  Up here in northern MN, it's possible to hit 70 degrees 
quite early in the spring before the irises have had a chance to grow 
much at all.  If it's true that borer eggs hatch at 70 degrees, we can 
have borer larvae emerging before iris fans.  I've often wondered where 
borer larvae go under such circumstances and assumed they head straight 
for the rhizomes.  Obviously, a foliar spray won't protect my irises when 
they have little or no foliage, so I use the granules instead.

Last year was the first year I used Merit granules, and I couldn't have 
been happier with the results.  I applied 1 tsp per plant (or clump, 
regardless of size) very early when fan growth was just an inch or two 
out of the ground.  A Bayer rep had told me the effects would last all 
season, so I wasn't concerned about applying it too early.  I just wanted 
to make sure the plants had time to absorb the Merit through their root 
systems before temps rose enough to hatch borers.

Although I did see some signs of borers in the leaves last spring 
("water-streaked" leaves with chewed edges), I didn't find evidence of a 
single borer having survived the trip down to the rz ... and I dug and 
divided hundreds of clumps last summer.  What a joy to NOT find a single, 
hollowed out rz!  

I've got a bucketful of Merit in my garage waiting for a nice, rainy 
forecast.  I'm a believer!


USDA zone 3b, AHS zone 4 - northern MN
normal annual precipitation 26-27"
slightly acid clay soil

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