Rain, Alfalfa, and Wheat

Rain, Alfalfa, and Wheat

Well ........ heck!  We need a rain!

Alfalfa insect pressures in the last ten days have been tremendous. 

 It was my observation that any pyrethroid with a chaser of clopyrifos (example Grizzly and Nufos or Baythroid and Lorsban) had a good initial knockdown of insects.  You did not have any trouble seeing the ground littered with dead worms and aphids. However the efficacy of the chemicals did not seem to last very long and in 5 or 6 days it was time for a respray.

There are probably several things happening.  The alfalfa plant seems so distressed, I suppose from lack of moisture, that we are not getting any help at all from the plants self defense mechanisms.  It does not seem to be growing worth a darn. Thus you can probably throw the economic threshold numbers out the window for our area this spring.  If any number of worms were left in the field it seems to be too many, even with numbers so low that in a normal year we wouldn't even notice them.

Because of lack of growth and the explosion of the weevil hatch, we are often forced to spray basically bare dirt with some alfalfa stems sticking up.  This allows very little of the plant to take in the chemical for residual affects.  There often has been no plant to protect.

Also, about the time the weevil exploded  this area had 6 to 7 days of no sun and 40 degree temperatures. Dry......, no sun,......... cold................nothing is going to work very well......... evidently

We seem to be having some luck with Steward and am cautiously optimistic, but even this chemical's company says 6 inches of growth is needed for a 14 day residual. 

Much the same can be said in regards to insects in our wheat crop.  With our wheat crop under stress it is not going to take nearly as many aphids to hold it back as in a year with normal moisture.  With the crop as valuable as it is it won't take as many bushels to treat it either.  So again, I think the economic threshold numbers for aphids in our wheat crop are being lowered. 

We do have aphids in much of the wheat and some spraying is beginning to take place.  It takes approximately 1.1 bushel to protect your crop. 

There are many beneficial insects out there as well (lots of lady bug larvae, and mummies on the leaves) so it is going to take a judgement call on the producers part, factoring in the weather, economics, and beneficials.

 Plan your work, work your plan.

All of this is probably something a good 1 to 2 inch rain would fix.




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