Entomology Update for July 2017

Late July and the beginning of August indicates the time to again intensify the careful management of internal fruit feeders.
Entomology Update for July 2017 - News


Codling moth injured apple fruit. Photo: G. Krawczyk, Penn State

Based on the captures of moths in the sex pheromone traps, all four main lepidopteran pest species, codling moth (CM) and Oriental fruit moths (OFM) and leafrollers such as tufted apple bud moth (TABM) and to a lesser degree, obliquebanded leafroller (OBLR), started their consecutive generations (second for CM, OBLR and TABM, and third for OFM), and if not controlled, each pest can cause injuries to maturing fruit. The egg hatch models provide estimation of insect development based on accumulated degree days (i.e., egg hatch) but do not take into account the site specific management activities conducted earlier during the season in each orchard.

If the actual control of the earlier generation(s) was effective, there is a chance that no control or only very limited management will be necessary for this current generation. The captures of male moths in the sex pheromone traps placed in orchards should be able to help to decide "if" and eventually "when" the treatment is needed. Properly maintained sex pheromone traps should provide the definitive answer about the actual pressure from various insect pests and help to choose the best management options.

First generation codling moth injury on apple. Photo: G. Krawczyk, Penn State

If insecticides are needed, products from IRAC Group 28 (ryanodine receptor modulators) such Altacor®, Exirel®, Minecto Pro® and Besiege® or a single product (Delegate®) from the IRAC Group 5 (nicotinic acetylholine receptor agonists; spinosyns) are highly active against CM, OFM, TABM and OBLR larvae. For the highest efficacy, insecticides used for the management of CM and OFM need to be applied before larvae enter the fruit, which usually happen in less than 24 hours after the egg hatch. After larvae are already inside the fruit, no product will be able to manage them.

Larva of oblique banded leaf roller in peach. Photo: G. Krawczyk, Penn State

In orchards using an effective CM and/or OFM mating disruption treatment, only leafroller control may be necessary and products such as Intrepid ® (ecdysone receptor agonist, IRAC Group 18) will provide effective leafroller control. In orchards managed with products approved for organic production, applications of codling moth granulosis virus (Madex® HP or Cyd-X®) should start right at the beginning of the moth flight and be repeated at intervals no longer than 7 days. Madex HP should also provide good control of Oriental fruit moth larvae. Leafrollers can also be managed by applications of products containing Bacillus thuringiensis (Dipel®) or spinosyns (Entrust®).

Brown marmorated stink bug

While the need and the actual intensity of CM or OFM management during the late summer is highly correlated with the effectiveness of the early season activities directed against these pests, the necessity for the management of brown marmorated stink bug (BMSB) in August and after is almost completely independent from previous management activities in orchard. During the late summer and fall high numbers of BMSB adults are moving into orchards from the surrounding vegetation such as woods or field crops. The migrating BMSB adults and nymphs developing from eggs deposited in orchards potentially can cause significant damage to fruit until the harvest.

Brown marmorated stink bug adult and nymph on foliage. Photo: G. Krawczyk, Penn State

The on-site monitoring still remains the best indicator if treatment targeting BMSB are necessary. The BMSB monitoring lures and traps from AgBio Inc., AlphaScent Inc., Sterling International, and Trece Inc. are commercially available either directly from the manufacturer, specialty stores or stores like Walmart, Lowe's or Home Depot.

For the best detection of BMSB adults and nymphs the BMSB multiple monitoring traps should be placed either at the border of the woods next to an orchard or under trees in the first row in the orchard. At least a single additional trap should also be placed somewhere in the middle of the orchard to monitor a potential pressure from BMSB populations established by adults bypassing the border of the orchard and flying deeper into the plantation. For the best results the Ag-Bio Dead-Inn® pyramid traps need to be placed on the ground under the trees while the Rescue® traps (small green "rocket like traps") should be placed in the tree canopy making sure they are in contact with the foliage. While low numbers of captured BMSB adults may not always validate the necessity for an insecticide treatment, a detection of live BMSB nymphs in traps placed in orchards warrants an immediate insecticide application.

With all "traditional pests" also potentially present in the orchard, it is very important that the choice of insecticides directed against other pests would also take into consideration the possible control of BMSB population present in orchards at the time of application. The list of BMSB effective insecticide options includes products with only few distinctive modes of action: pyrethroids (IRAC Group 3A) such as Bifenture® EC and 10DF and Brigade® WSB (the same AI, bifenthrin), Danitol® (fenpropathrin), and Warrior® (cyhalothrin); neonicotinoids (IRAC Group 4A) such as Actara® (thiametoxam), Assail® (acetamiprid), Belay ® (clothianidin), Venom® and Scorpion® (dinotefuran); and one carbamate product (IRAC Group 1A), Lannate® (methomyl).

With at least 10 more weeks of possible BMSB activity to go (until mid-October on late maturing apple varieties), it is extremely important that growers plan ahead with the choice of products utilized against BMSB, and preserve the most effective options, especially with the shortest Pre-Harvest Intervals (PHI), for applications when the pressure from this pest will increase in the later part of this season, usually in September and early October.

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 .

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)

Abbreviations: RBLR - redbanded leafroller; STLM - spotted tentiform leafminer; OFM - Oriental fruit moth; CM - codling moth; TABM - tufted apple budmoth; OBLR - obliquebanded leafroller; DWB - dogwood borer; PTB - peach tree borer; LPTB - lesser peach tree borer


Degree-Day Table

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 (July 01) mentioned in the table are based on the weather forecast.

Rock Spring1-Jul8-Jul15-Jul21-Jul28-Jul