Environ. Horticulture, Pears, Cherries, and Viticulture
University of California
Environ. Horticulture, Pears, Cherries, and Viticulture

Strawberries

The Use of Esteem, Oberon and Prevam for the Control of Greenhouse Whitefly in Strawberries

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.

 

Greenhouse whitefly adults with waxy exudate.
Greenhouse whitefly adults with waxy exudate.

Greenhouse whitefly eggs.
Greenhouse whitefly eggs.

Control of greenhouse whitefly eggs with various materials.
Control of greenhouse whitefly eggs with various materials.

Control of greenhouse whitefly nymphs with various insecticides.
Control of greenhouse whitefly nymphs with various insecticides.

Control of greenhouse whitefly adults with various insecticides.
Control of greenhouse whitefly adults with various insecticides.

Posted on Thursday, October 11, 2018 at 1:31 PM

Extension Meeting: Management of Gophers and Groundsquirrels

To be held at our office at 1430 Freedom Blvd, Suite E in Watsonville on October 24.  Sign in starts at 730 am and the meeting goes to noon.

Get here early, looks to be a pretty heavily subscribed event.  Agenda below.

Posted on Monday, October 8, 2018 at 12:17 PM

Article: What it Takes to Successfully Introduce Mechanization of Harvest into a Cropping System

The following is an article from a California Agriculture magazine published in the year 2000, and in using two case studies from California, is quite instructive on what it takes to successfully introduce mechanization and automation into a cropping system. 

A few summary points about mechanization of harvest and the article linked below.

Success is found in integrated programs of research work: In 1950, a breeder and agricultural engineer at UC Davis worked hand in hand to develop a system for mechanized harvesting of processing tomatoes.  The plant breeder developed a tomato that could withstand the stress of mechanical harvest, while the engineer came up with a machine that could successfully remove the tomato from the plant. 

The gains are worth the effort: This mechanized harvester reduced the labor requirement per ton of tomatoes to 2.9 hours from 5.3 hours.   A similar arc of reduction of labor took place in rice, where combinations of cultural practices, plant breeding and mechanization resulted in a reduction of 4.5 labor hours to harvest a ton of dry rice in the 1930's to 0.4 labor hours to harvest a ton of dry rice in the early eighties.

Success takes time: After 12 years of hard work on the part of the team from UC Davis, the mechanical harvester for processing  tomatoes was commercially available.  In rice, the large reduction in labor hours noted above took close to fifty years.  Nevertheless, they happened.

 

 http://calag.ucanr.edu/archive/?article=ca.v054n03p51

So what does this all mean for us in the berry business?  For one, waiting for Captain Marvelous to show up and build a machine in one go that picks fruit like a person in fields just like we are now growing them doesn't appear to have a precedent.  

On the other hand, given the two case histories outlined above I am convinced that an integration of disciplines, a lot of hard work as an industry and the patience to support this endeavor through is what it will take to build the harvester we all want.

The article is very much worth the read, probably not more than 15 minutes of your time.  Read it.

Mechanized harvest of tomatoes in California.
Mechanized harvest of tomatoes in California.

Posted on Friday, September 7, 2018 at 1:42 PM

Redberry Mite in Primocane Blackberries?

No, I don't think so and see for yourself with the photo series below.  I have quite a few more of these pictures, but I think you'll get the point with the two series posted.

I've been getting a host of questions concerning what appears to be redberry mite on primocane blackberries - PrimeArk 45 and proprietary varieties -  with red druplets mixed in with ripe ones, but if one marks the fruit and waits for a couple of days the red druplets have ripened fully.  Now, the question is how this uneven maturity affects fruit quality, but that is something to be answered another day.

July 11, 2017 fruit 1.
July 11, 2017 fruit 1.

July 13, 2017 fruit 1.
July 13, 2017 fruit 1.

July 11, 2017. Fruit 2.
July 11, 2017. Fruit 2.

July 13, 2017. Fruit 2.
July 13, 2017. Fruit 2.

Posted on Thursday, September 6, 2018 at 12:41 PM

Is There a Botanist in the House?

A recent page one article in a major American newspaper lamented the declining number of skilled botanists in the US. Something about animals being more interesting, with the net result that we are left with very few people who can distinguish between hydrangeas and rhododendrons, and speak intelligently about the difference in plants of thorns, spines and prickles (each arises from a different biological systems).

Well, lament no more my friends.  Our Environmental Horticulture Farm Advisor, Steve Tjosvold, who is a botanist par excellence, has offered to share his 30+ years in the field with us on this subject and many others on his just launched nursery and flower grower blog. 

Have a look:

//ucanr.edu/blogs/NurseryFlower/

 

I've had a request for the link to the article from a dear reader, it's right below.  It seems that these Wall Street Journal links are not free, I apologize for that, but you have my commitment that I will explain clearly what the article is about in my posts.

Thanks all!

 

https://www.wsj.com/articles/rhododendron-hydrangea-america-doesnt-know-anymore-1534259849?mod=searchresults&page=1&pos=1

 

 

 

Posted on Sunday, September 2, 2018 at 2:21 PM

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