July 9th Apple Talk Call Summary

Apple Talk Conference Call Summary

Tuesday July 9th, 8:00 – 9:00

Presenters: John Aue, Threshold IPM.

Moderator: Peter Werts, IPM Institute of North America; questions or comments, pwerts@ipminstitute.org.

July 9th Call download Here

Severe weather forecasted for July 9 to 11
High winds and hail forecasted may pose risk for fireblight and black and white rot infections.  Growers always have the option of applying streptomycin within 24 hours after a storm and can get pretty good control using this strategy to prevent fireblight and waiting more than 24 hours offers little to no utility.  If terminal buds are set, the danger of fireblight after a storm is much reduced and may not need a strep application following a storm.  Growers need to assess inoculum levels.  If by this time of the year you have not seen blossom or shoot blight, the inoculum may be very low and the need to apply strep may be diminished.  Young trees with actively growing shoots may need strep depending on level of storm damage and fireblight inoculum.

Follow up from July 2nd call
Apple pictures posted on the web after the July 2nd call that had speckling on them could be blister spot.  Conditions for blister spot would be high humidity, and rain and could become present on other varieties, though it is most common on Mutsu.  

Sootyblotch and Flyspeck (SBFS)
The first incidences of flyspeck has been found in orchards, however sootyblotch has not developed yet.  Many growers have now put on Topsin or Indar.  Recent research suggests that relative humidity hours may have more relevance to infections for summer diseases than leaf-wetting hours.  When we have 90 to 95% humidity, then each hour is equivalent to one hour of leaf wetness re summer disease infection periods.  The current model is to apply materials for summer diseases when we have reached 175 leaf-wetting hours from petal fall.

Japanese Beetle (JPB)
Japanese beetle has been detected in southeastern Wisconsin and in the Upper Mississippi River Valley region.  Last year growers had lower pressure due to the drought, however eggs have good survival in the soil and John is suggesting this year may be more severe for JPB.  Neonicotinoids or Neem oil will both repel JPB, but need to be applied prior to establishment of JPB populations.  In organic systems Neem oil will need to be applied frequently.  Surround could also be an experimental option for repelling JPB and would also be applied to help reduce apple maggot damage.  Pyganic is the only organic product that would provide knock-down control.  Applying Pyganic during the day could be a strategy to knock down JPB and protect beneficial insects because it will dissipate very fast in the sun light.

Codling moth
At this time in the season it can be hard to determine if we are at the end of first generation or the start of second generation.  The best way to differentiate is to use our degree days.  If you are at 800 to 900 degree days from biofix, we are still in first generation.  Normally by this time, trap counts will have declined dramatically.  However, there are instances where trap counts may not drop off, and this could be true where orchards were not managed for codling moth due to a poor crop in 2012.  Typically there are 1000 degree days between first and second generation codling moth. 

With the variability in trap counts and being on the edge of generations, how do we know if we need to reapply?  The better we manage first generation, e.g., frequent sampling, keeping pheromones refreshed and applying treatments when over threshold, will be a better use of financial resources now, rather than using it during second generation where, CM can become hard to control.

When can we spot spray for CM? Spot sprays may be an option during first generation when parts of the orchard may have trap counts that are below threshold, e.g., lots of beneficial insect activity.  If you spot spray, then it is important to keep sampling the areas that were not treated.

Apple Maggot
There are several effective methods to monitor apple maggot, including baited and unbaited red spheres and with yellow sticky boards.  The scent on the yellow sticky boards only lasts about a week to two weeks and should be changed accordingly.  If an apple maggot fly is caught on the yellow card, we can wait up to a week to spray.  If apple maggots are caught on red spheres, sprays should be applied immediately.  For a baited trap the threshold is five per trap and in unbaited traps the threshold is one.  Determining if apple maggot can be spot sprayed is dependent on the number of traps placed out and where the trap counts are located.  Trap captures concentrated in one area of the orchard versus in all blocks would determine the if the whole orchard should be treated, or just part.  We also need to consider the varieties we are monitoring, e.g., early varieties versus late harvested fruit.  In organic production, we need to keep on top of our kaolin and pyrethroids.  In conventional orchards we can be looking at low rates and alternate row applications.  AM move around enough that an alternate row middle spray can be effective.

 Leafroller sampling
The summer generations of redbanded leafroller (RBLR) and obliquebanded leafrollers (OBLR) need close attention, as OBLR is still hatching out in many areas and in several weeks there will be the summer RBLR flight.  Since terminals have already set, leafrollers which emerge now will feed on fruit.  Whereas if shoot growth is still growing, then leafrollers will continue to feed on shoot growth.  If these leafrollers are present our larvacides or products including Bacillus thuringiensis (Bt) will be very effective and offer a good alternative to using a neonicotinoid.

San Jose scale (SJS)
Sampling for SJS crawlers (immatures) is best done using double-sided tape on scaffold limbs with weekly monitoring.  The question that is important to address is how many branches and trees need to be sampled?  Over the last 12 years John has not needed to use more than a two or three scale tapes per orchard.  However, this year John is not picking up crawlers on tapes, yet finding the damage on fruit.  Growers are suggested to increase the number of tapes they have on trees and to be persistent with weekly monitoring.

First generation crawlers should be winding down and we would be seeing the white caps settling down on the fruit and branches.  If we have been taping and have not seen crawlers in the last month, John is suggesting to spend additional time looking for scale on fruit when we change our tape.

If you have not taped this year, it is important right now to scout the fruit for San Jose scale crawlers.  Find hot spots and flag areas for more intense monitoring during second generation.  If scale has been found on fruit or you’re seeing a combination of lemon-yellow crawlers and scale caps, there is still utility for using an insecticide against this generation, e.g., Esteem, neonicotinoid or summer oil.  The second generation will be sometime in mid to late August. 

Wooly apple aphids (WAA)
Colonies are growing and it is advised to be looking for predators and parasites.  Syrphid fly maggots are very common predators of WAA.  We are seeing some vegetative growth is becoming completely covered and can become very infested by harvest. 

Applications of neonicotinoids against WAA for a number of years, or against other pests in the orchard, we may not see a very dramatic response, e.g., resistance potential.  This is because of the multiple generations of this pest that may be being exposed for multiple years.

None of the options for managing WAA are fantastic or cheap and the best resource is to encourage beneficials in controlling WAA. While the beneficials have not had the best track record on rosy apple aphids, they have been very effective with WAA.

The little black and shriveled WAA are from parasitic wasps.  Little maggots from syrphid fly larva are also common right now in WAA colonies.