Mike and I concur that there are lots of scenarios and opinions on how to use this product. Here are our efforts to simplify the use of Retain
•Apply Retain 4 weeks ahead of when you would predict you would pick McIntosh assuming Retain was not used. Apply Retain 3 weeks ahead of expected harvest (again pretending that Retain was not applied) for all other cultivars.
•We expect this to be a difficult season for pre-harvest fruit drop and encourage growers to tank mix NAA (at least 10 ppm or 4 oz. Fruitone-N or 4 fl. oz. of Fruitone-L per 100 gal using tree row volume) with each Retain application to drop-sensitive fruit.
•We look to be 10-14 days ahead of “normal maturity” this year. As mentioned in my 7/12 grower message, this means that the next 7 days may be the correct timing for Retain + NAA applications to McIntosh. In Northern New Jersey followed by Gala a few days later. On McIntosh, use the full Rate of Retain + 10 ppm NAA at the 4 week timing, or better yet, use a ½ Retain rate + 10 ppm NAA at 4 weeks and repeat this spray again 2 weeks later.
Note: In North and Central NJ many of our apple blocks are PYO. For these blocks you may want to increase the rate suggestions below on Gala and Honeycrisp to further delay maturity and increase color. Gala and Honeycrisp ripening in August may be of little value for PYO marketing.
Traditionally I use the ½ rate of Retain on Gala and HC at the Rutgers Snyder Farm but this year will be increasing the rate to delay maturity.
•On Gala, use a ½ rate of Retain 3 weeks before expected harvest of Non-Retain fruit to avoid greasiness and stem-end splitting and slow color development. This means Retain could be applied by this weekend in early-maturing blocks and early next week in most blocks.
•On Honeycrisp, use 1/3 to ½ rate of Retain applied 2-3 weeks before expected Non-Retain harvest of fruit (I would go with the 1/3 rate). We have not tested it, but tank-mixing 10 ppm NAA with Retain could also be beneficial on Honeycrisp. As with Gala, Retain could be applied by this weekend in early-maturing Honeycrisp blocks and early next week in most blocks.
•Include an organosilicone surfactant such as Silwet (12 oz. per 100 gal) or Silken, as leaving this out will significantly reduce ReTain’s effectiveness.
•The label recommends you maintain spray tank solution pH of 6-8. Adjust the pH if necessary and check it again if you don’t spray out a tank right away. · Note: there Tables On Retain Timing in Last weeks (July 17, 2012) Fruit Plant and Pest Newsletter for greater detail.
Anticipated predicted dates for the Hudson Valley New York
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Normal Gala / Honeycrisp first-pick date if
no Retain used
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2012 Gala / Honeycrisp first pick harvest date if
no Retain used
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Timing of single Retain+NAA application
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August 27
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August 17
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July 27
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August 30
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August 20
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July 30
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September 2
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August 23
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August 2
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September 5
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August 27
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August 5
|
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September 8
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August 30
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August 8
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Comments
These are my best guesses based
on what I have heard/learned (Mike F) All these estimates may need to be adjusted
to earlier dates if July and August turn out to be significantly warmer than
expected. Other scenarios are possible and may provide equal or better results.
Talk with you consultants and get their opinions. Harvest delays because
of poor color development may be problematic as you need to schedule harvest of
other cultivars, and fruit may already be too large on poorly-cropped
trees. However, harvest delays also help fill bins with bigger fruit that
didn’t fall on the ground, and these fruit do have more time to develop color
during cooler weather.
I strongly encourage growers to
view the video of Dr. Robinson’s helpful presentation on these issues which he
gave at Fruit School. Click to view just the summary and conclusions (12 minutes)
or see the entire presentation (46 minutes) or find them on the website. You will need Adobe
Flash Player software on your computer which is available free at (http://get.adobe.com/flashplayer/). Your
feedback on these videos and their value is encouraged.
If you wish to discuss you particular situation with Retain please contact me at: cowgill@njaes.rutgers.edu
