Jul 8, 2020
Mid-summer management of insect pests in fruit orchards outlined by PSU

In most Pennsylvania fruit orchards the first-generation activities of codling moth, tufted apple bud moth, or oblique-banded leafroller adult moths are almost over.

It will take from two to four weeks before the second generation moths will become present again in orchards. The notable exception is Oriental fruit moth (OFM) which already started the second generation flight. If the numbers of OFM moths collected in traps exceed 10-15 moths per week per trap, an insecticidal control will be warranted to manage this pest. If mating disruption products are not used to control Oriental fruit moth, applications of Altacor, Delegate, Exirel, Verdepryn, or Voliam Flexio should be used to manage OFM.

In orchards with OFM mating disruption, the OFM monitoring should be done using a new Pherocon OFM Combo lure (Trece, Adair, OK), which is able to detect the presence of OFM moths even in orchards with a OFM mating disruption (MD) program. In addition to pheromone traps, the visual search for injuries caused by the first generation larvae on top of shoots provide very accurate indicators about the presence of the OFM population. On peach trees, the flagging of terminals (Photo 1A) is easy to detect however on apple terminals the detection of OFM injury is less obvious (Photo 1B)

Photo 1. Peach (A) and apple (B) terminals injured by the first generation Oriental fruit moth larvae. Photo: Greg Krawczyk, Penn State

Other most common mid-summer threats include Japanese beetle (JB), various species of leafhoppers, San Jose scale (SJS), and woolly apple aphid (WAA). The distribution of these mid-summer pests usually tends to be highly localized and the actual management may be needed only in some isolated orchards or even only parts of the blocks. Special attention needs to be placed on the protection of newly planted, young trees. If the management of leafhoppers such white apple leafhopper (WALH) potato leafhoppers (PLH) and rose leafhopper (RLH) is needed, neonicotinoid insecticides (i.e., Actara®, Assail®, Belay®, or Admire Pro®) should provide excellent control.

Last week scouting in orchards located in western and south-central Pennsylvania revealed the presence of first Japanese beetle adults (Photo 2). Although fruit trees are only one of the common hosts for this insect, the JB feeding can cause severe defoliation of pome and stone fruit trees as well as grapes. Some apple cultivars such as Honeycrisp and most plums are especially attractive to JB. Adult beetles can also feed directly on the fruit. The neonicotinoid insecticides mentioned above should help with at least partial control of this pest as well as a treatment of carbaryl (Sevin) which should also be effective against JB. The commercially available Japanese beetle traps are very effective in attracting high numbers of beetles into the vicinity of the baited traps, however, due to potential limits in their beetle re-capture abilities, traps should not be placed too close to the protected plant(s).

Photo 2. Injuries caused by feeding Japanese beetle adults. Photo: Greg Krawczyk, Penn State

Early July is also the time to scout vigilantly for initial signs of WAA infestation (Photo 3). During past few weeks, we started to notice first build-ups of white webbing produced by migrating WAA. Biological control agents such as syrphid flies Heringia calcarata and Eupeodes americana or tiny parasitic wasp Aphelinus mali should provide effective control of WAA. If pesticide control is needed to control WAA products such as Diazinon® or Movento® should provide good control.

Photo 3. Woolly apple aphids on apple terminal: (A) early signs of infestation and (B) late WAA colony with some aphids parasitized (black mummies) by parasitic wasp Aphelinus mali. Photo: Greg Krawczyk, Penn State

If present, fresh San Jose scale infestation from the first summer generation of crawlers should also be easy to see on fruit (Photo 4). The next good timing for the most effective protection of fruit should be determined by the capture of males in commercially available SJS pheromone traps (usually near the end of July – early August).

Photo 4. (A) Apple fruit infested by San Jose scale crawlers (late June), (B) injuries on young branch, and (C) SJS monitoring trap. Photo: Greg Krawczyk, Penn State

Phytophagous mites such as European red mite or twospotted mite can be controlled with a wide assortment of summer acaricides: Envidor (IRAC Group 23), Kanemite (IRAC Group 20B), Nexter (IRAC Group 21A) Portal (IRAC Group 21A) or Zeal (IRAC Group 10B). When deciding which products to use, please remember about resistance management and do not use products from the same IRAC group during two consecutive seasons.

2020 season weekly updated seasonal moth captures in pheromone traps located at the Fruit Research and Extension Center for the most common fruit pests are available at:

Insect Pests – Trap Count Data

Greg Krawczyk, Penn State University

Photo at top: Foliage of apple tree after intensive feeding of Japanese beetle. Photo: Greg Krawczyk/Penn State


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