4-11-2007
Adding Nulure degrades spinosad.
Dr. Bob Van Steenwyk, Entomology Specialist at UC Berkeley, just sent out a message to all the walnut farm advisors that adding NuLure to Success (for walnut husk fly control) lowers the pH to a point that may make the Spinosad less or ineffective. Thanks to Mike Devencenzi for bring this to his attention!
I'm attaching Bob's summary of the situation and his test results showing the degree of pH change.
Bob used baking soda to correct the pH issue but of course you would use a commercial pH adjustment product for a field application.
Janet Caprile
Dear Walnut Advisor/Specialist.
It has come to my attention from Mike Devencenzi, a PCA in the Stockton area, that the addition of NuLure to Success (spinosad) for walnut husk fly control caused a dramatic shift in the pH of the solution. I determined the pH of various concentrations of NuLure and molasses with deionized and industrial water at UCB. The data is attached. I then discussed these finding with Dr. Bisabri of Dow AgroSciences. He indicated that a pH level less than 6.0 will reduce the longevity of spinosad and would recommend the pH level to range from 6.0 to 8.0. I then determined the effect of adding a small amount of sodium bicarbonate (Arm & Hammer - baking soda) to various solutions of NuLure or molasses and water. The data is attached. The small amount of baking soda buffered the solution and brought the pH into line. Please advise your walnut growers who may be considering the use of Success for control of walnut huskfly to modify the pH of the spray solution. If you have any questions, please feel free to call or e-mail.
Bob Van Steenwyk
Date |
Amount of NuLure |
pH |
|
(brought up to 100 ml) |
Deionized water a |
Tap water b |
|
1/19/2007 |
0.000 ml |
6.10 |
8.33 |
|
0.125 ml |
4.08 |
6.49 |
|
0.250 ml |
3.96 |
5.87 |
|
0.500 ml |
3.94 |
4.72 |
|
1.000 ml |
3.84 |
4.22 |
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Date |
Amount of Molasses |
pH |
|
(brought up to 100 ml) |
Deionized water a |
Tap water b |
|
1/31/2007 |
0.000 ml |
6.12 |
8.16 |
|
0.125 ml |
6.00 |
7.71 |
|
0.250 ml |
5.72 |
7.22 |
|
0.500 ml |
5.47 |
6.83 |
|
1.000 ml |
5.40 |
6.48 |
a Deionized water was used to bring final volume up to 100 ml in the first experiment |
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b Tap water was used to bring final volume up to 100 ml in the second experiment |
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Date |
Amount of NuLure + NaHCO3 |
pH |
|
(brought up to 100 ml) |
Deionized water a |
Tap water b |
|
2/13/2007 |
0.00 ml + 0.0 g |
5.79 |
8.32 |
|
0.25 ml + 0.0 g |
3.95 |
5.25 |
|
0.25 ml + 0.2 g |
7.17 |
7.05 |
|
0.25 ml + 0.4 g |
7.62 |
7.25 |
a Deionized water was used to bring final volume up to 100 ml in the first experiment |
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b Tap water was used to bring final volume up to 100 ml in the second experiment |
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