Brief: Oriental Fruit Moth (OFM) can now be found in commercial orchards. Infestations of apple terminal shoots and fruit was observed over the past week. This season we are seeing roughly 20% flagged shoots in untreated Gingergold trees on M-26.
If OFM has become problematic in your orchard consider employing pheromone trapping, implementing mating disruption pheromones to prevent mating and egg laying (for both OFM and codling moth), improve spray timing using degree-day models and trap data to establish our site biofix, improving spray coverage and using the most effective insecticides and viruses at the recommended timing for the early Lepidopteran complex.
Management: If OFM injury is occurring now it is too late for 1st generation management as larva, residing in stems or fruit, are unlikely to come in contact with the insecticide. Management employing insecticide applications or mating disruption should be timed based on second generation OFM emergence. If mating disruption (MD) is used, orchards should be at least 5 to 10 acres in size for MD to be effective.
Biology: Oriental Fruit Moth Grapholita molesta, in the Tortricidae family, is native to China. It is an invasive pest of apple and peach, first introduced to Japan then North America estimated to be in 1913 on infested nursery stock. OFM can be found throughout the tree fruit growing regions of Europe, Australia, New Zealand and many other parts of the world.
Most of the major tree fruit lepidopteran pests are Tortricids, such as codling moth, lesser apple worm and oriental fruit moth, and are often attracted to the same pheromone used in traps to monitor the Lep. complex.
In the northeastern United States, the OFM has three generations (flights) per year.
Eggs are found on upper leaf surfaces, frequently on the terminal leaf of a young shoot. Individual females can lay up to 200 eggs during the 1st generation beginning in early May. The succeeding overlapping generations extend into September and October. The incubation period varies with temperature, ranging from three to four days at midsummer, to seven to fourteen days during the cooler part of the season. Just before the larva hatches, the dark head capsule can be seen through the egg. This is known as the “black head” stage.
OFM larvae feed on larvae tunnel in tender twigs causing twig die-back of peach, apple, quince, pear, plum, cherry, apricot and nectarine. Larvae will enter into growing shoots and tunnel into the stem causing the terminals to wither and brown, at times resembling fire-blight strikes and often called flagging.
As fruit develop the larvae will often enter near or through the stem end of stone fruit or calex end of apple and bore directly into the interior of the fruit. Mature larvae are dirty white to pink in color, with a reddish brown head capsule.
As they feed through apple flesh to the core they do not enter the seed carpel nor do they feed on the seed. This behaviour differentiates OFM from CM, which do feed on apple seeds. OFM also have a structure on the last segment of the abdomen called anal comb, which CM do not have.