Peach shoot injured by Oriental fruit moth larvae. Photo: G. Krawczyk, Penn State
Timing of insecticide application
The 2017 biofix for the Oriental fruit moth (OFM) was established on April 5th, tying the earliest ever biofix date. The first codling moth (CM) adults were collected on April 27th, also making it one of the earliest biofixes on record. The biofix for tufted apple bud moth (TABM) is still not established. The biofix, which is defined as the beginning of sustained adult moth activity, is established based on adult male moth captures in pheromone traps.
A correctly established biofix will improve the prediction of the development of pest populations in the field and also help with performing future pest management practices at the best timings. For example, this year, based on the OFM egg hatch model forecast, the post-bloom treatment applied during the next few days (petal fall on apples) will be timed at about 50 percent of OFM egg hatch and should provide effective control of OFM larvae on apples.
The timing of an insecticide application after the petal fall stage on apples is well synchronized with the best period for the control of European apple sawfly (EAS), rosy apple aphid (RAA), OFM, and plum curculio (PC). If other pests such as European red mites (ERM), scale insects (SJS), and other aphids were not controlled before bloom, the same application also provides the opportunity to manage this group of pests.
Young apple fruit injured by plum curculio adult. Photo: G. Krawczyk, Penn State
Choosing insecticide control
The choice of insecticide should be determined by the pest(s) to be controlled. Some broad spectrum products such as Assail® or Avaunt® plus neonicotinoid insecticides such as products containing imidacloprid (e.g., Provado®) should provide good control of all pests listed above. If only selected pest species require special attention, specific selective insecticides should be considered. Older neonicotinoids (Admire® Pro, Actara®) applied at the petal fall timing will provide good control of aphids and leafminers but they will not be effective against many other pests. However, both products provide good contact activity against brown marmorated stink bug (BMSB) and PC (if present in the orchard).
Apple leaves injured by rosy apple aphids. Photo: G. Krawczyk, Penn State
If only leafrollers, OFM, and leafminers are the intended target(s) of the treatment, then an application of Intrepid®, Proclaim®, Rimon® will be sufficiently effective. If no dormant oil was applied during the pre-bloom period, ERM populations can be reduced with an application of Agri-Mek® (or other formulations of abamectin) plus a penetrant (e.g., oil) at the petal fall stage. Abamectin still offers good control of ERM and spotted tentiform leafminers (STLM), and fair to good control of WALH. Agri-Mek should be applied before the leaves harden off, generally within 10 days of petal fall. The ovicidal acaricides Apollo® or Savey® can be applied during the petal fall to first cover period. Other acaricides such as Acramite®, Envidor®, Portal®, Kanemite®, Nealta®, Nexter® or Zeal® are registered mainly for summer mite control.
Due to valid concerns with the possible pesticide direct and sub-lethal effects on honey bee and other native pollinator populations, it is strongly recommended that growers avoid using insecticides until honey bees are completely removed from orchards.
Codling moth (CM)
Although the biofix for CM is already established (April 27th), the insecticide based management of this pest should not start until about two to three weeks after petal fall (i.e., sometime around 250-350 DD50). The recommended, broad-spectrum larvicidal insecticides to control CM include: Altacor®, Assail, Avaunt, Delegate®, Exirel®, Voliam® Flexi or Besiege ®. A second insecticide application against CM, depending on the pest pressure, is usually needed around 14-17 days after the first application. During the last few years we observed an extended flight of CM, sometimes lasting until the end of June. If traps continue to catch significant numbers of CM adults in orchards during June and two applications for CM are already made, a 3rd insecticide application may be needed during this late period as well.
In organic apple orchards, the Cydia pomonella Granulosis Virus (CpGV) present in products such as Cyd-X®, Cyd-X HP and Madex HP® provides the best alternative for the management of CM. In our research trials, weekly applications of the CpGV even at low rates (e.g., 1.0 fl oz /ac) when combined with mating disruption program provided CM control at levels comparable to insecticide treatments. Madex HP in addition to CM neonate larvae should also provide effective control of OFM larvae. In orchards with a low CM pressure mating disruption should be considered for management.
Our latest field trials with various mating disruption (MD) products for the control of CM and OFM documented excellent efficacy of these products in our orchards. CideTrak®, Checkmate® and Isomate® mating disruption products are commercially available and should be considered as a part of the seasonal CM and OFM management program. If MD products will be used for the control of CM, the pheromone dispensers should already be placed in orchards (i.e., before CM biofix). Although, the best timing for placing OFM MD products was before the OFM biofix, delayed placement of OFM MD products should still be very effective and reduce seasonal pressure from this pest during consecutive OFM generations.
Tufted apple bud moth (TABM)
Sex pheromone traps are also the best tool to decide if and how intensively to manage TABM. During the last few years we have observed increased numbers of TABM males collected in sex pheromone traps in commercial apple orchards. If Altacor, Delegate, Exirel, Voliam Flexi, Besiege, Intrepid® or Rimon are to be used for TABM control, 1-2 complete, precisely timed applications of those products per brood are recommended. Use of Altacor, Delegate, Exirel and Voliam Flexi should provide excellent control of both CM and TABM. If applying two complete sprays against TABM, the first application should be made at about 10-30 percent egg hatch (500-600 DD base 45) followed by a second application (if necessary) at about 60-70 percent egg hatch (800-850 DD).
The low rate of Intrepid (10-12 oz/acre) should provide excellent control of TABM larvae but this low rate of Intrepid will not control CM or OFM. If applying only one complete application of the above mentioned compounds against TABM, this spray can be made at 30-40 percent egg hatch (640-695 DD). Products containing Bacillus thuringiensis such as Dipel® provide a valuable alternative for leafroller control in organic orchards.
Insecticides effective against TABM should also provide good control of obliquebanded leafroller (OBLR) larvae, but at least one additional application of an effective insecticide may be necessary to control this pest in orchards with a history of OBLR infestation. Phenologically, the most effective timing for controlling OBLR larvae usually occurs at the timing for the second application of insecticides for TABM, followed by an additional treatment about 10-12 days later.
Pear psylla (PP)
Our recent orchard counts of pear psylla (PP) on pear foliage revealed the presence of all nymphal stages (including the late instar nymphs called "hard shells") and eggs. At this time the majority of nymphs are feeding mostly along the main vein on the leaves and the use of a magnifying hand lens is often necessary to detect their presence. For proper monitoring during the petal fall period, at least 10 leaves per tree (5 spur and 5 recently expanded shoot leaves) on a minimum of five trees per block should be examined. The action threshold for an insecticide application is reached when on average 0.5 nymph per leaf is found.
Pear psylla adults feeding on pear shoot. Photo: G. Krawczyk, Penn State
The application of Agri-Mek® SC (4.25 fl oz/acre) or one of the generic products such as Abacus®, Abba®, Reaper® or Zoro® containing abamectin (IRAC Group 6) still remains one of the best PP control options at the petal fall to PF + 10 days timing. Various formulations of available abamectin products contain different percentages of active ingredient; therefore it is always advisable to use the material at the high end of recommended rate listed on the label for each individual product. A penetrating surfactant such as a summer oil at 0.5-1.0 percent concentration is a necessary addition to Agri-Mek in order to provide the best residual control. For good coverage of trees this spray should always be applied with at least 100 gal of water per acre.
Due to hardening of the foliage and decrease in absorption of the active ingredient after this petal fall application window, the abamectin containing products will provide less effective PP control. Products such as Actara®, Centaur®, Delegate®, Exirel®, Movento®, Sivanto®, Portal®, Admire Pro or Nexter® can also be used if additional control options are needed. Another option for PP control is the use of kaolin clay Surround®. If good coverage is achieved, Surround (applied at 25-50 lb/acre) can be a very effective additional tool for PP control and apossible repellent for BMSB. Surround is registered for use in organically managed orchards.
Using Products Containing Bifenthrin
Bifenthrin, the active ingredient belonging to the pyrethroid insecticide group (IRAC Group 3A), received a special Section 18 Emergency Exemption Registration from US EPA (April 20, 2017). Under this Section 18 Emergency Registration, products containing bifenthrin can be used on apples, peaches and nectarines (bifenthrin already has a full registration on pears) up to 14 days before harvest (14 d PHI, 12 h REI). Bifenthrin can be applied up to two times per season, with at least a 30 day interval between applications.
Three commercial products with bifenthrin are available for Pennsylvania growers to use against BMSB: Brigade® WSB at the rate 12.8 to 32.0 oz (FMC Corporation, Philadelphia, PA), Bifenture® EC at the rate 5.12 to 12.8 fl oz (United Phosphorus Inc., King of Prussia, PA) and Bifenture® 10DF at the rate 12.8 to 32 oz (United Phosphorus Inc.). The higher rates of each product are recommended for the most effective BMSB control.
- Please remember, another formulation of bifethrin, Brigade 2EC is not included in the Section 18 Emergency Registration and this product is not registered for the use on fruit (except pears).
- This Section 18 Emergency Exemption registration for products containing bifenthrin will expire on October 15, 2017.
Seasonal Activity of Fruit Pests
2017 season weekly average captures of adult moths in pheromone traps located at the Penn State Fruit Research and Extension Center, Biglerville, PA (Adams County)
Accumulated degree-days base 43°F from Jan 01 for each reported year (courtesy of SkyBit, Inc.) The accumulated degree-days for the last date of the current year (April 28th) mentioned in the table are based on the weather forecast.