Orchard Entomology Update: June 4, 2021
Codling Moth, Oriental Fruit Moth, and Leafrollers Update
During the 2021 season, using pheromone traps located at the Fruit Research and Extension Center in Biglerville orchards, the biofix for Oriental fruit moth (OFM) was established on April 6, 2021, codling moth (CM) on April 29, 2021, tufted apple bud moth (TABM) on May 5, 2021, and for obliquebanded leafroller (OBLR) on May 31, 2021.
As of June 03, 2021, the flight of the first generation of OFM adults is completed and OFM control is no longer feasible—most surviving larvae are actively feeding either inside fruit or growing shoots. In contrast, the first-generation CM and TABM adult moths are in the midst of their reproductive activities.
If warranted based on the data from CM monitoring traps, the optimal timing for the second treatment against CM larvae should occur sometime early next week (June 7–8), at about 550DD50 which is forecasted for the Biglerville area for Monday–Tuesday of next week. This second CM treatment will synchronize well with the optimal timing for the control of TABM. In addition to CM and TABM, if a third insecticide application against CM will be necessary, it should also control OBLR larvae. However, the exact dates and necessity for this treatment will vary from orchard to orchard. If products such as Altacor®, Besiege ®, Delegate®, Exirel®, Verdepryn ®, or Voliam Flexi® are to be used for the CM control, 1 to 3 complete, precisely timed applications of any one of those products per generation are usually sufficient to achieve effective control.
Application(s) conducted in mid-June and later should not only provide excellent control of CM but also of TABM and OBLR. Application(s) of BT-based products or Intrepid are only effective against leafrollers and will not control codling moth. For organically managed orchards, if needed, weekly applications of codling moth granulosis virus (CpGv) as in Cyd-X® or Madex HP® will provide good control of codling moth while applications of BT based products or Entrust® should effectively manage leafrollers.
In orchards with CM and OFM mating disruption programs, insecticide applications may not be necessary to manage CM and OFM but sprays targeting TABM should be applied at about 10–30 percent egg hatch at 500-600 DD45 followed by a second application (if necessary) at about 60–70 percent egg hatch at 800–850 DD45. If applying only one complete application of the above-mentioned compounds against TABM, this spray should be done at 30–40 percent egg hatch (at 640–695 DD).
Insecticides effective against TABM should also provide good control of OBLR larvae, especially around mid to late June as larvae of both species can be spotted on the trees at that time. Since young OBLR larvae prefer to feed inside growing terminals, the insecticide coverage of new growth plays a critical role in controlling OBLR larvae. If needed, only complete sprays are recommended against this pest. The better the coverage, the better control will be achieved. The insecticides recommended for the OBLR control during this time of the season include Altacor, Besiege, Bacillus thuringiensis (BT) products, Delegate, Intrepid, Verdepryn, Voliam Flexi, or Exirel.
Figure 1. Fresh injury on apple caused by codling moth larvae (left); tufted apple budmoth flagging injury on foliage (right). Photo: G. Krawczyk, Penn State
Weekly update information on pheromone trap counts for codling moth, obliquebanded leafroller, oriental fruit moth, redbanded leafroller, spotted tentiform leafminer, and tufted apple bud moth can be found during the growing season at Insect Pests - Trap Count Data.
Pear Psylla Update
Based on our observations from the Fruit Research and Extension Center pear orchard, the results of the early 2021 season pear psylla (PP) management seems to be quite variable, with many PP adults and eggs present on the trees and foliage, despite the petal fall application of AgriMek®. The next critical period to control is the second generation of pear psylla, occurring right now. We have started to observe the hatch of the young PP nymphs.
An application of effective insecticide is recommended if the action threshold of 1 live nymph per leaf is reached. If chemical control is required, then Admire ® Pro, Actara 25WP or Assail® 30SG (plus a quart of summer oil) should be very effective for control of pear psylla nymphs. In addition, Nexter ®75WP or Portal ® should also provide good to excellent control of pear psylla as well as European red mites.
Other products such as Delegate, Exirel, Sivanto®, Movento®, Verdepryn, or Closer® should also be considered if multiple applications of insecticides will be needed as the season progress. If application against PP nymphs is needed, all above-mentioned products should be used at the high end of the label rates recommended for pear psylla.
Figure 2. Pear psylla adults (left) and adult and late instar nymph (right) on pear foliage. Photo: G. Krawczyk, Penn State
Apple Aphid - Spirea Aphid Complex
Multiple newly established colonies of apple aphid/spirea aphid were observed during the last two weeks in orchards across Pennsylvania. The aphid colonies observed are mostly on new fresh foliage. The aphids in most cases should and will be controlled very effectively by natural enemies such as syrphid larvae, lacewing larvae, aphid midge, ladybird adults and larvae, and some Braconids wasp. If an average of more than 4.2 leaves per shoot are infested by aphids and less than 20 percent of colonies have predators within the colony, an insecticide application may be needed to lower the aphid population. Please remember to use pesticides with low toxicity to the beneficial organisms.
Also, if rosy apple aphids (RAA) were not controlled effectively during the petal fall period, in some commercial orchards it is not difficult to find infestations on new terminals caused by the summer generation of RAA. If more than one RAA colony per tree is present at this time of the season, an effective aphicide treatment is recommended.
Figure 3. Aphids on apple foliage: (left) rosy apple aphid colony inside folded leaf; (center) rosy apple aphid established colony; (right) fresh spirea aphid initial colony. Photo: G. Krawczyk, Penn State
Periodical Cicada Update
The periodical cicada adults have been present in the woods for about 10–14 days. The low temperatures during last weekend slowed down the mating process of cicadas and now is about the time when the oviposition process will start. The main injury cicadas will cause to trees is the slicing of branches and deposition of eggs inside of the split by females. Female cicadas usually choose young branches for this activity. On matures trees, injured branches can be removed during the winter pruning. But on young trees, splits caused by cicadas can affect the shape of the canopy and slow the growth of the trees.
Adult cicadas are strong fliers and young orchards located close to old, established woodlots are especially prone to severe injuries of branches. If control is warranted, applications at high label rates of broad-spectrum insecticides such as pyrethroids (Asana®, Danitol®, Warrior®, etc…) or neonicotinoids (Actara®, Admire ® Pro, Assail®, etc…) should control adult cicadas and prevent injuries.
With periodical cicadas expected to hover around for the next 5–6 weeks, at some locations multiple applications of insecticides may be necessary to prevent significant injuries to young trees.
Figure 4. Periodical cicada adults aggregating at apple trees (left); slit on apple branch caused by oviposition activity of female periodical cicada (right). Photo: G. Krawczyk, Penn State
