A couple of months ago, I had a meaningful conversation with my colleague Gerald Holmes at the CalPoly Strawberry Institute concerning extension of our research results. It dawned on me that over time I have accumulated quite a bit of information that could be pretty useful, but haven't really distributed it all that widely, just because like many of you I like doing stuff outside with my hands and also get distracted by more immediate needs.
Anyway, I'll try and get some of these things out to this blog as we go along. The following is a nice piece of work I did together with Plant Sciences in 2005 testing a variety of chemistries on whitefly in strawberry.
Introduction: Greenhouse whitefly, Trialeurodes vaporariorum, has been a pest of strawberries for many years in the Monterey Bay growing region. In addition to the weakening of plants, whitefly feeding deposits honeydew on leaves and fruits and has been implicated in the dispersal of several viruses in strawberries.
This trial was designed to test the efficacy of the insecticides Esteem, Oberon and Prevam in controlling greenhouse whitefly in strawberries grown on the Central Coast of California.
Materials and Methods: The trial was done as a randomized complete block design of four replicates of three 30 foot long by 4 foot wide beds per treatment on PS592 variety strawberries in a field in Salinas, California.
Application: An application of all materials and mixes was made on August 11, 2005. Subsequent applications of certain materials were made on August 21, August 31 and September 9, 2005. See Table 1 below for timing of each pesticide treatment.
Experimental applications were made at the rate of water carrier of 150 gallons per acre at 150 psi pressure. Applications were made with a motorized backpack sprayer with a hand held boom consisting of 10 8001 flat fan nozzles.
Table 1. Treatments, Rates and Timing
|
Product 1,2 |
Rate (Product / Acre) |
No. of Appls. |
Application Interval |
|
1. PrevAm |
0.4 % v/v (= 51.2 ozs. / 100 gals) |
3 |
10 days |
|
2. Esteem 0.86EC |
10 fl ozs / acre |
2 |
30 days |
|
3. PrevAm + Esteem 0.86EC (tank-mix) |
0.4 % v/v (= 51.2 ozs. / 100 gals) + 10 fl ozs / acre |
2 |
30 days |
|
4. Oberon |
16 fl ozs / acre |
2 |
30 days |
|
5. PrevAm + Oberon (tank-mix) |
0.4 % v/v (= 51.2 ozs. / 100 gals) + 16 fl ozs / acre |
2 |
30 days |
|
6. Brigade WSB |
32 ozs / acre |
2 |
10 days |
|
7. Pyganic 1.4EC |
64 fl ozs / acre |
3 |
10 days |
|
8. UTC (untreated control) |
----- |
----- |
----- |
Evaluation:
Counts of adult whitefly were made by randomly sampling and turning over, without detaching from the plant, 40 medium-aged strawberry leaflets per replicate plot and counting the number of adults present. Adult whitefly counts were be made from all of the treatments at the following intervals: 0-day (just prior to first application), 1-day after each application, and 10-days and 20-days following the final application of treatments 2 and 3.
In addition to the adult counts, separate counts of whitefly eggs and whitefly nymphs were made using a random sample of at least 10 medium-aged leaflets per replicate plot, taken at each evaluation interval specified above for the adult evaluations.
Results were tested statistically using a multiple comparison procedure (Least Significant Difference at the 95 percent level of significance) to determine whether the means of counts and percentages per treatment were significantly higher or lower from the other treatments. The graphs below give a pictorial presentation of the results.
Conclusion: Treatments of Prevam and Brigade limited numbers of whitefly eggs, nymphs and adults to levels significantly lower than the untreated control on many evaluation dates. Esteem and Oberon mixed with either Prevam or Kinetic gave exceptional control, with consistent and significant control over other treatments of whitefly eggs, nymphs and adults over the course of the study.
Attached Images:
