June 25th Apple Talk Summary

Apple Talk Conference Call Summary

Tuesday, June 25th, 8:00 – 9:00
Presenters: John Aue, Threshold IPM.
Moderator: Peter Werts, IPM Institute of North America; questions or comments, .

June 25th Call Download
Call Download

Call Summary

Stone Fruits
Items to note regarding stone fruits, both cherry fruit fly and lesser peachtree borer are now flying. Stone fruits are a prime target for plum curculio which is still in some orchards and remains to be ovipositing. Michigan State University put two articles out this week regarding brown rot, the links are below.

Fungicide protection for ripening tart cherries with European brown rot blossom blight symptoms

Scout now for sporulating American brown rot fungus in sweet cherry orchards

Leafhoppers– Be paying attention to non-bearing trees and continue to check the terminals for Potato leafhopper, as they are beginning to appear.

Leafminers– Spotted tentiform leafminer are flying right now, the first flight was quite small however we are now in the second flight and if numbers increase we should be looking for leafminer in the next few weeks.  Spotted tentiform leafminer have not been an issue for a number of years.

San Jose scale– John still has not found any crawlers however according to the model, they should be around. It is important to stay on top of monitoring.  Management options for San Jose scale include a neonicotinoid, Esteem, Movento or summer oil.

Rosy apple aphid– Many rosy apple aphid colonies are now gone as a result of predators or because they have moved on to summer hosts.  However, if colonies are still present and infesting terminal growth, this could be cause for concern.

Obliquebanded leafroller- Obliquebanded leafrollers are now hatching.  Michigan State University has found a rough correlation between numbers in traps and larva that hatch.  We can have a significant amount hatching from a summer flight, even if there are not many in your traps.  Growers may begin checking for terminal damage and monitoring for the many beneficials that feed on them.  If the summer generation of leafroller is not controlled now with biological controls or insecticides, the second generation that occurs in late August will be even harder to control and can contribute to significant cat-facing damage.

Apple maggot– Historically growers are encouraged to hang apple maggot traps by the fourth of July. In the last few years, rain has not been strongly correlated to apple maggot emergence and it is a possibility that with soggy soils we could get some pupae drowning prior to emergence. Typically apple maggot emergence is correlated to a combination of soil moisture and soil temperature.

Codling moth- Cool weather has kept codling moth flights down the last few weeks.  If we have had more than two inches of rain in less than a week, it is necessary to recover.  If a codling moth application went on more than a week prior to rain, we are out of protection, but the need to reapply can be based on trap counts.  If there is no rain, we can count on 10-14 days of protection with Delegate or Assail and perhaps a bit more with Altacor, at the max rate.

If we did not have rain, disregard trap counts for the first seven days after the application.  Watch flight during the second seven days of our coverage period.  Any female codling moth flying in the first seven days, will hatch out in the second seven days, and is within the active period of control (when we don’t have rain). If the numbers in the second seven days are elevated, then those eggs will be hatching after the material runs out.

It is much better to spend more money now on first generation codling moth, rather than battling this pest during second generation.

BT or virus will not last more than five or six days under normal conditions and is not rainfast at all, it is also susceptible to ultraviolet degradation.


Fireblight– If you are noticing fireblight showing up in your orchard, streptomycin should not be applied unless there are very high winds or hail.  Streptomycin would need to be applied within 24 hours of a damaging event to maximize the utility.  As trees stop vegetative growth, the necessity to apply streptomycin begins to decrease because the bacteria are less likely to spread.

Summer diseases– It has been a very cool summer for diseases however, there is no degree day model for summer disease.  The model uses accumulated leaf-wetness hours and petal fall tree phenology.  Infections for the summer disease complex are happening now, even though we may not see infections now, they will show up in a month.  For organic growers, now is the timing for Serenade.  For conventional growers who would apply Indar, Flint, Sovran, Luna, Fontelis and Topsin, John would apply at 175 and 250 leaf wetness hours from petal fall.  Options for counting would be: counting wetness hours from petal fall, one week after petal fall or one week after the last application of a systemic.  Traditionally the model indicates to only use wetting periods of four hours of longer.  However, most weather stations do not give us information on how long each wetting period was.  This could be problematic this year with high humidity and lots of rain, and thus it may not be necessary to worry about the four hour interval.  If your weather station allows you to drop out wetting periods less than four hours, then proceed in that manner.  Otherwise, stick with the straight total from petal fall and use the 225 to 250 for initial application and then use the 175 for subsequent applications.  With so much rain, John is suggesting to stick with 175 if we are using Topsin M.

Scab– Even one or two leaf lesions on a tree could result in many fruit lesions a few weeks from now.  Regarding scab, if you have had four to eight inches of rain in the last week, it does not matter when the last application was, because there is no more residual remaining on the leaves.  Applications should be made at a higher rate on scab susceptible varieties, but would not need to apply that high of a rate to Honey Crisp.

If we have scab – we need to use the highest rate possible of Captan on the susceptible trees, Syllit (dodine) could still be an option as well. As far as recover, if we don’t have rain it will last a month, but we lose half of our cover with every inch of rain, so it is necessary to reapply after every two inches of rain.


Check out rainfastness characteristics from last week’s call.

Rainfast characteristics of fruit crop insecticides