Normally, this number of heat units is accumulated around two weeks after the petal fall on apples and corresponds with the application of insecticides at the first cover timing. This season, this DD accumulation took a little longer and according to the CM egg hatch developmental model provided by SkyBit Inc., for the Biglerville area the 5-10 percent CM egg hatch, is forecasted to occur around May 20th. This will represent an optimal timing to initiate management activities against CM this season.
If mating disruption materials are not used to control this pest, applications of Altacor®, Delegate®, Exirel®, Minecto Pro® or Voliam Flexi® should provide excellent control of CM. In organic orchards, codling moth granulosis virus, CpGv (Cyd-X®, Cyd-X HP® or Madex XP®) applied after the beginning of CM egg hatch and then repeated every 7 days should also provide very good control of CM neonate larvae.
Since the egg hatch of the first generation Oriental fruit moth is already completed, the OFM larvae feeding inside growing terminals and inside fruit are protected from insecticides and will not be controlled by any insecticide treatment applied at this time.
Peach tree terminal injured by Oriental fruit moth. Photo: G. Krawczyk, Penn State
Plum curculio (PC) adults are finishing their movement and presence in the orchards, however with the current warmer weather PC adults are still able to cause damage to stone and pome fruit. For effective control of this pest, the PC model developed by the Cornell University entomologists recommends insecticide treatments against this pest until accumulation of 308 DD base 50F after petal fall on McIntosh apples. In orchards where PC is considered an important pest, additional treatment of insecticides such as Avaunt, Imidan, Assail or Exirel may still be helpful to protect fruit from PC feeding and oviposition.
Plum curculio adult on apple fruit. Photo: G. Krawczyk, Penn State
The monitoring of aphids needs to be continued, especially for adults and nymphs of green peach aphids on stone fruit and first spirea aphids on apples. A threshold of one GPA colony per nectarine tree or five colonies per peach tree is recommended in Pennsylvania. The presence of predators such as ladybird beetles or syrphid fly larvae in about one out of five aphid colonies may lead to successful biological control. If the aphid populations will continue to increase for the next few weeks, if needed, a neonicotinoid insecticide application should be also effective in controlling these two aphids.
During this past week, we observed increased presence of brown marmorated stink bug adults in traps placed in woods and around fruit orchards. Although the numbers of captured BMSB continue to be relatively low (at least compared to captures normally observed during the late summer period), traps baited with one of the three most common lures: Stink Bug Xtra Combo (from Ag-Bio,Inc.), Stink Bug Rescue lure (Sterling International, Inc.) and Stink Bug Dual lure (from Trece Inc.) seems to provide solid information on potential movement of adults into orchards. If BMSB treatments are considered to be necessary, then application of neonicotinoid insecticides normally used for control of aphids such as Actara®, Assail ®, Belay®, or Admire Pro® should also be effective to control BMSB, however each product will need to be used at the high end of the recommended label rates.
Brown marmorated egg mass and early instar nymphs. Photo: G. Krawczyk, Penn State
In the Biglerville area (FREC orchards) the 2017 season biofix for Oriental fruit moth was established on April 05; spotted tentiform leafminer on April 01, codling moth on April 25 and tufted apple bud moth on May 01. Biofix for obliquebanded leafroler is still not established in south central PA.