June 24, AppleTalk Call Summary

AppleTalk Conference Call Summary
Tuesday, June 24th, 2014, 8:00 – 9:00 a.m.
Presenter: John Aue, Threshold IPM.
Moderator: Peter Werts, IPM Institute of North America; questions or comments, pwerts@ipminstitute.org

June 24th call download: Click here

Fire blight  5:00
Fire blight is beginning to show as shoot blight in many orchards.  Removing, i.e., breaking-off or pruning, strikes at least one foot below the canker may help eliminate the spread of disease.  If pruners are used, disinfect between each tree.

Spotted tentiform leafminer and white apple leafhopper 7:00
Spotted tentiform leafminer (STLM) and white apple leafhopper (WALH) have multiple generations a season; this year populations appear low.  Growers should recognize signs of STLM as tissue feeding mines on the topside of leaves.  The second STLM flight should be beginning soon, if trap counts increase scout for an abundance of mines.  Symptoms of WALH can be seen as white speckling on the inside of the tree canopy.  Damage from second generation is considerably worse than first generation, if WALH is noticed, scout for the next generation in late July and early August.  First generation nymphs may have already molted into adults.

Aphids and mites   9:10
Green, rosy and wooly apple aphid and mite populations appear low this year.  Wooly apple aphid colonies that were observed several weeks ago are not showing further growth.  Contact John or Peter if these pests are a problem in your orchard.

Obliquebanded leafroller 10:35
Obliquebanded leafroller (OBLR) are beginning to hatch in the southern half of the state.  Products, i.e., Altacor (chlorantraniliprole) or Delegate (spinetoram), applied for codling moth, except granulosis virus and mating disruption, should provide adequate control of OBLR.  Beneficial insects should also aide in suppression.  Second generation larvae can be more problematic, and difficult to control then first generation OBLR.  High population may cause damage to fruit and significant damage to terminals on young and non-bearing trees.

Scouting for fruit and foliar feeding should begin seven days after moths are caught in pheromone traps.  Note: Management threshold and feeding pressure does not correlate to trap captures.  OBLR is resistant to many of the organophosphates and most of the neonicotinoids are not very effective on OBLR.

Flower thrips   13:50
Observe terminals and shoots for leaf curl, resulting from feeding.  The damage is most prevalent on the midrib of the leaf.  Brown, feeding scars will be present on the underside of leaves.  May be of concern on young or non-bearing trees and thrips will continue to feed until terminals have set and often not a concern on mature trees.

Potato leafhopper  15:35
Potato leafhoppers are appearing on terminals and shoots, particularly orchards in close proximity to hay and alfalfa fields.  These are also often only a problem on young and non-bearing trees.  Symptoms include upwards, cupping of leafs on terminal shoots.

San Jose scale  19:35
Monitoring for San Jose scale (SJS) crawlers should begin in the southern half of the state. Monitor known hotspots with black electrical tape applied to suspect scaffold branches.  With adhesive side towards tree, wipe a thin layer of petroleum jelly on the outside of the tape.  If populations are high, concentrate a few traps in areas with greatest pressure.  Increasing the number of monitoring sites may help eliminate false negatives.  Note: Low trap captures do not reflect overall pressure, i.e., false negatives.  Low trap captures may indicate the beginning of the hatch.  First generation SJS hatches over a narrow period, while second generation hatches over a wide period. Widespread catches of 10-15 crawlers in a couple of days or 10 crawlers on one tape with zero on all other tapes, may warrant application.  Conventional products for summer control include Esteem (pyriproxyfen) or Movento (spirotetramat).  Organic growers are limited to summer oil and biological control.

Codling moth  31:15
Codling moth flights will begin to decreasing from 700-900 degree days (DD) after first biofix.  Low trap counts, e.g., five per week may suggest tail end of first generation.  Trap counts should be uniform throughout orchard, if you have hot spot, this may indicate migration from outside the orchard.  Second generation biofix typically begins 1000DD, base 50, from first generation codling moth biofix.

Codling moth degree day accumulation

Location DD, base 50 Biofix Date of last DD reading
Burlington, WI 339 6/1 6/23
Chilton, WI 366 6/1 6/23
Galesville, WI 394 6/1 6/24
Fitchburg, WI 400 6/1 6/24
Chippewa Falls, WI 404 6/1 6/22
Harvard, IL 428 6/1 6/24
Blanchardville, WI 454 6/1 6/24
La Crescent, MN 504 5/30 6/23

If weather conditions threaten product longevity, use lower rates when conditions allow, then reapply with remainder of high rate after severe weather passes.  Note: Product sustainability relies on effective application timing and retaining an appropriate dose of insecticide on the fruit surface.

Sooty blotch and flyspeck   55:40
New research suggests, for effective summer disease control, fungicides should be reapplied every 185 leaf wetness hours from petal fall to harvest.  See Cornell’s Scaffold Fruit Journal from June 23.  A link to the article is below.

Cedar apple rust
Legions should begin appearing on susceptible varieties.  At this point in the season no control is available, no subsequent infections will take place.

Apple maggot
Baited and unbaited, red spheres and yellow sticky boards are utilized at different points in season to track emergence and population trends.  Unbaited and baited yellow sticky boards should be hung in late June to detect adult emergence.  Insecticide applications can typically be timed one week after first capture on unbaited boards.  Red spheres should be hung the first week in July.  Flies captured on unbaited red spheres warrant an immediate insecticide application.  Thresholds vary from five flies per baited trap and one fly per unbaited trap.  Monitoring should begin in early varieties.  Organic suppression includes Surround WP (kaolin) and PyGanic (pyrethrins).  Conventional control may be achieved with lower insecticide rates and alternate-row-middle applications.  If pressure is localized spot spraying may offer adequate control.  Monitor traps to determine location and method of application.  Note: The fruit essence on baited traps is viable for one week and should be changed accordingly.

Apple maggot emergence is linked to soil moisture and temperature.  During the past few years, rain has not been thoroughly correlated to apple maggot emergence in our region.  John predicts that with soggy soils, some pupae may possibly drown prior to emerging.

Additional articles and resources