June 14, AppleTalk Conference Call

AppleTalk Conference Call Summary
Tuesday, June 14, 2016, 8:00 – 9:00 AM
Guest speaker: Larry Gut, Michigan State University Tree Fruit Entomologist
Presenter: John Aue, Threshold IPM
Moderator: Peter Werts, IPM Institute of North America; questions or comments, pwerts@ipminstitute.org

June 14th call download: Click Here

Question and answer session with Larry Gut, Michigan State University Tree Fruit Entomologist

Codling moth flights
We have observed over the last several years the 1st generation codling moth (CM) flight has been characterized by an immediate peak, e.g., occasionally up to 40-60 males in the first week, when we biofix, or shortly after, followed by low numbers for duration of the generation. Might this be a result of several years where 1st larvacide application was delayed – perhaps because of erratic early catch numbers?

  • Larry is also observing a condensed flight in Michigan and believes the sporadic weather patterns, e.g., extreme changes in temperature over a short period, are contributing to the majority of the emergence occurring all at once. He recommends to control first generation through peak egg hatch, i.e., 650-700 DD from biofix. If CM trap captures are below threshold and 400-450 DD has accumulated since biofix, reapplying a second larvicide for first generation may not be warranted.
  • In MI the majority of growers who are catching really high numbers of CM, e.g., 40-60 CM /trap/week, are usually growers who are relying on older chemistries, e.g., organophosphates and/or pyrethroids, for control.

Mating disruption
What percentage of MI growers are using some form of mating disruption?

  • In the last four years, 40-50% of acreage in MI has employed mating disruption (MD). Some growers have made an economic decision to not use MD in 2016, since CM moth fruit injury have been extremely low from many years of continuous use of MD.

What is your current opinion on different MD systems, i.e., on density of sources needed to shut down 90-95% of mating? Does endemic population size affect efficacy (% shutdown), or do you get X amount of shutdown with X number of sources, independent of the number of females per acre?

  • Larry is in favor of hand-applied dispensers, e.g., CheckMate CM-XL 100, IsoMate C TT, because there is more flexibility in adjusting rates, which can be decreased if pressure is light and control is good; standard rates are 100-200 dispensers/acres. Aerosol emitters, e.g., CheckMate Puffer CM-O, are currently used on approximately 1000 acres in MI. There is minimal flexibility in reducing rates below the standard rate of one to two emitters per acre to accommodate variable pressure. Aerosol emitters are less labor intensive, but may not be suitable for blocks less than 20 acres.
  • Growers who had MD in a year of frost are usually happy because they can get through the season with a minimal spray program.
  • Check with your local supplier to verify what MD products are approved for use in your state.

Do most growers using MD routinely use an ovicide or larvicide? How many of these applications are made per season per generation?

  • Most MI growers using MD apply one or two larvicides to manage CM and obliquebanded leafroller (OBLR). Special importance needs to be given to monitor OBLR in orchards with MD. Obliquebanded leafroller moths can travel long distances and low trap captures usually means they don’t need to be controlled. John has observed wide variation in trap counts in one block to the next; thresholds that require a larvicide treatment are 20-30 OBLR/trap/week. One application of a Bacillus thuringiensis (Bt) product, e.g., Agree, Deliver, Dipel, during bloom will offer great control of OBLR, green fruitworm and redbanded leafroller. Control may not be achieved from a delayed petal-fall application. Bt must be eaten by the insect to be effective, and warm temperatures, e.g., > 70°F, are needed in the 72 hour period following an application for good mortality. Research in Washington is finding OBLR that are developing resistance to the newer chemistries, e.g., diamides or spinosyns, and installing MD for OBLR may help mitigate resistance. Factors to consider when looking for resistance include population growth and a corresponding spray history that may have exposed the three generation of OBLR to the same class of insecticide annually.

Essential requirements for monitoring in MD and non-MD blocks

  • Larry recommends to use more pheromone traps (rather than less) and to place them in the best location possible, e.g., high spots not low spots, inward 100 feet from the perimeter and placed in the top third of the canopy. Make sure to keep foliage from blocking the trap entrances.
  • It is important to monitor LAW and OFM in blocks using MD. If larvae are found in fruit use a hand lens (≥ 10X magnification) to look for the presence or absence of an anal comb to accurately identify the species; for photos visit http://www.fruit.cornell.edu/lof/ipm/pdfs/codling_moth.pdf
  • Monitoring area of the orchard drops from 20% to 2-4% when MD is used. I have also heard it described as a CM trap will monitor 2.5 acres, but under MD reduces to about 1/10 -2/10 of an acre. So I feel like John’s numbers are a little made up. Basically, we need to find sources for this, because this is a significant reduction in the monitoring area.
  • Use at least two OBLR traps per farm and one per block when using MD.
  • Codling moth threshold is five moths per trap in one week, not among several traps.

Other codling moth-related questions
This year, some growers applied Belay (clothianidin) when our CM biofix accumulated 250-300 DD and were still experiencing an extended plum curculio emergence.  The Belay better managed input costs, where there was a reduced crop and are still interested in using a neonicotinoid to manage apple maggot (AM).  If a neonicotinoid, i.e., imidacloprid, e.g., Admire Pro, Alias or Montana, is applied without another CM larvacide, e.g., Delegate, Altacor, Avaunt, in a differing IRAC class for AM which coincides with second generation CM, can this exposure, despite imidacloprid not being labeled for CM, select for neonicotinoid resistance?

  • Larry does not think this is a sustainable method due to resistance concerns and recommends growers to rotate insecticide classes for management during first and second generation.

John Wise, MSU Entomologist, has completed extensive research on rainfastness of insecticides. Did this research reveal if removal of insecticide residues during a hard rain create any significant mortality of hatching larvae? Is there any grace period before a required re-application?

Do you know of codling moth efficacy results from the use of combination materials, e.g., Tourismo (buprofezin, flubendiamide), Voliam Flexi (thiamethoxam, chlorantraniliprole), etc.? Is their efficacy against codling moth similar to their single diamide component counterparts, i.e., Belt and Altacor?

  • Larry notes that some of these combination materials have performed very well in efficacy trials. See spray guide for efficacy trial information.
  • Exirel (cyantraniliprole), same IRAC class (28) as Altacor, has excellent efficacy for AM control.

Do you anticipate pressure increasing from any of our economic pests in the near future?

  • Apple maggot is really beginning to show up in MI. The newer materials used for AM are effective but do not have the same mortality as some of the older materials and it’s likely AM populations are building to the critical threshold that’s allowing injury to become visible in orchards. For certain growers with high pressure, saving Imidan (phosmet) for summer time AM control is an excellent option, especially when applied as alternate row application at 2 lb./acre.