Photo 1. Obliquebanded leafroller injured new growth on apple tree. Photo: G. Krawczyk, Penn State
The SkyBit egg hatch developmental model (SkyBit, Inc.) forecasts about 70 percent egg hatch for both leafroller species on June 16. Insecticides such as Altacor®, Delegate®, Exirel®, or Voliam Flexi® should provide excellent control of TABM and OBLR, and additionally also control remaining first generation codling moth (CM) larvae. While TABM larvae tend to feed on older leaves, the preferred feeding sites for OBLR larvae are usually located at the top of the growing new shoots. If OBLR is the dominant leafroller species in the orchard, then applications of insecticides may need to be repeated to protect developing new foliage (Photo 1).
Codling moth (CM)
Although the first generation codling moth adults are gradually ceasing their flight, in some orchards the flight of this generation adults may last a little longer. Please use on-site observations (e.g., pheromone traps) to decide if additional insecticide applications are needed for the CM control. In addition to products listed above for the control of leafrollers, which are also effective against CM, the organically approved codling moth granulosis virus CpGv (in producst such as Cyd-X®, Cyd-X HP® or Madex XP®) should also provide good control of CM neonate larvae.
Oriental fruit moth (OFM)
The second generation flight of Oriental fruit moth (OFM) just started this past week and if trap data indicates the necessity for a special treatment (10 plus moths per trap per week), the week of June 20 represents a good timing to control OFM (about 10 percent egg hatch on June 17). Most products mentioned in the leafroller's section should also provide good control of OFM larvae. In peach and apple orchards, the presence of OFM population can also be relatively easy assessed by visual scouting for the presence or absence of wilted shoots (Photos 2a,b,c).
Photos 2a,b,c. Injury caused by Oriental fruit moth larvae feeding inside young peach and apple terminal shoots. Photos: G. Krawczyk, Penn State
It is also a good time to scout for the presence of leafhoppers, especially white apple leafhopper (WALH), potato leafhoppers (PLH) and rose leafhopper (RLH). All three species are somehow similar in appearance however the RLH nymphs can be distinguished by the presence of small black spots on the thorax and wing pads. Leafhopper adults and nymphs feed on the foliage of fruit trees with PLH being also a known vector able to spread fire blight. Special attention needs to be directed toward protecting newly planted orchards. Neonicotinoid insecticides such as Assail®, or products containing imidacloprid should provide excellent control of these pests.
Photo 3. Leafhopper nymphs and winged spirea aphid on apple leaf. Photo: G. Krawczyk, Penn State
Brown marmorated stink bug (BMSB)
During last few weeks we also continue to find increased numbers of brown marmorated stink bug (BMSB) in areas around commercial peach and apple orchards. While in majority of orchards no special treatment against BMSB should be necessary, the detection of juvenile BMSB stages (nymphs) usually warrants a specific insecticide application targeting BMSB, especially in stone fruit orchards. Various trap and lures are available for monitoring the presence of BMSB in and around orchards. BMSB traps and lures such as Stink Bug Xtra Combo (from Ag-Bio,Inc.), Stink Bug Rescue lure (Sterling International, Inc.) and Stink Bug Dual lure (from Trece Inc.) should provide solid information on potential movement of BMSB adults into orchards and are very effective tools to detect the already existing presence of BMSB adults and nymphs. For the most effective and accurate detection of migrating stink bugs, the BMSB traps should be placed on the edges of orchards bordering woods or other possible sources of BMSB. The list of effective insecticides against BMSB includes most pyrethroids, neonicotinoids and Lannate®.
Photo 4. Brown marmorated stink bug adults and nymphs on soybean leaf. Photo: G. Krawczyk, Penn State
Woolly apple aphids (WAA), San Jose scales (SJS) and European red mites (ERM)
June is also a good time to start (or continue) extensive monitoring for woolly apple aphids (WAA), San Jose scales (SJS) and European red mites. The presence of white cottony fibers most likely found around leaf axils on sprouts or any wounds on wood suggests the necessity of insecticide application to control WAA (Photos 5a,b). Diazinon® or Movento® are the best choices for controlling woolly apple aphids, if the control can not be provided by natural enemies. Both products plus Centaur ® and Esteem ® will also help if San Jose scale crawlers are detected on the fruit or young shoots on the tree (Photo 6a,b).
So far, this 2017 season's atmospheric conditions were not too favorable for the development of European red mites, however the incoming hot and dry weather may still cause significant increase on the mite populations, especially if the beneficial organism such as predatory mites and/or Stethorus beetles are not present in the system. During the hot and dry summer days, the European red mites may complete a new generation in less than two weeks.
Photos 5a,b. Woolly apple aphid colonies on young apple branch. Photo: G. Krawczyk, Penn State
Photo 6a,b. Injuries by white peach scale on nectarine fruit (6a) and San Jose scale on apple fruit (6b). Photo: G. Krawczyk, Penn State
The insect pest control updates presented are for South-central Pennsylvania based on observations in Adams County. To view the insect hatch and trapping data for all major insect pests, please visit the Penn State Fruit Research and Extension Center (FREC) website. For control recommendations, refer to the Insect and Mite Control Toolbox - Apple-timing, Apple Efficacy, Pear-timing, Pear efficacy, Stone fruit-timing, Stone fruit-efficacy.