Oriental Fruit Moth One Shifty Pest

Every fruit crop has its insect nemesis. For peaches and nectarines, it is the Oriental fruit moth, the biggest insect pest headache for growers since it first appeared in the U.S. in early part of the 20th century. OFM thrives in both humid and dry peach growing areas and has many traits that have allowed it to adapt, survive, thrive, and cause mischief.

OFM is an Omnivore
Part of the reason that Oriental fruit moth (OFM) is successful is that it likes many different fruit crops. Although the primary hosts of the oriental fruit moth are peach and nectarine, it will also attack quince, apricot, apple, plum, cherry, pear, rose, and flowering cherry.

For Michigan, oriental fruit moth (OFM) was considered to be a minor pest on apples, usually worse when peaches were grown in the vicinity. Over the past 20 years, OFM has adapted to become a major pest in apples, at times the larvae of this pest is more common in fruit at harvest than codling moth.

A Cloud of OFM
Oriental fruit moth overwinter as larvae in silken cocoons on the tree or in the duff on the orchard floor. In the spring the larvae become pupa, and begin to emerge as adults during April, shortly before peach trees bloom. Time from egg laying to hatch can take anywhere from 5 to 21 days depending on the temperature.

The first-generation targets foliage and the rest seek out fruit. The first-generation flight is relatively well defined, but later generation flights two, three, and four blur together in a “cloud.” It is thought these later generations overlap because of different rates of larval development, depending on the different hosts and food sources.

As a result, it difficult to time summer sprays based on development models because there are no distinct peaks. Although pheromone trap catches can’t pinpoint the start of the summer and fall generations, they can indicate the relative size of the population and to some extent the need to apply insecticide.

Typically, a catch over a threshold of 10 to 20 or more moths per trap in a week can be taken as an indication that ongoing insecticide treatment is needed.

A Sneaky Pest
OFM can be a real problem in young peach orchards where early season larvae invade and distort tender young shoot tips, frustrating growers trying to grow a well-structured tree, and perhaps causing future canker problems. OFM are also capable of infesting young apple shoots, but the damage to these are generally minor and often overlooked. Infested shoot tips, particularly in peach orchards, become a major source of new moths for the second and third generations. As female moths can lay up to 200 eggs, the OFM population can build quickly, plus it has the reputation of being a sneaky pest.

The sneakiness is due to the summer and fall generation larvae often burrowing into fruit close to the stem. If it is a small larvae the entry hole is tiny, almost invisible, and the infested fruit are really difficult to sort out in a packing line. Packers have had to abandon complete fruit loads that have even a small amount of infestations of this type.

Wavering Resistance
OFM, like many other moth pests of fruit, is notorious for developing resistance to insecticides. With building resistance problems, a grower will see that insecticides do not last as long in the orchard, and, trap catches can skyrocket, reaching over 100 moths per trap in a single night.

Since the early 1990s, OFM has developed resistance to a wide array of insecticide types including organophosphate-types like Guthion and Imidan, carbaryl (Sevin), and the various pyrethroid insecticides, as has been well documented in Ontario, Illinois, and New Jersey. Fortunately, there are several classes of insecticides available for OFM management that can be used in rotation to help keep resistance to one class from building.

The good and also bad news is that resistance of OFM to an insecticide class can decrease over several years if use of that class is cut back. Although this seems good, it does leave the crop manager uncertain as to what is the resistance level to a particular insecticide in an orchard. Testing for insecticide resistance in an orchard is a slow and expensive undertaking, and currently is not practical for management decisions.

It takes real discipline to follow a good insecticide rotation program and there are always temptations to deviate. For example, pyrethroid insecticides are relatively cheap and they are a valued mix partner due to their broad spectrum activity against other pests such as tarnished plant bug, brown marmorated stink bug, and San Jose scale. Even though another insecticide may be in the mix to control OFM, the presence of the pyrethroid partner will keep nudging the insect population to maintain high pyrethroid resistance.

And don’t forget that pheromone disruption is a straightforward method to help control OFM. Disruption has proven to be particularly useful for reducing OFM populations that have gotten out of control. Mating disruption has its nuances as described in a recent article by Michigan State University researchers Larry Gut and Mike Haas. It is well worth reading.

Topics: ,

Leave a Reply

Stone Fruit Stories
Insect Control
August 22, 2017
Stink Bug Threatens High-Dollar Crops in California
While populations are low, it appears invasive pest has recently stumbled upon the state’s peaches and almonds. Read More
Stone Fruit
August 1, 2017
Researcher: Cherry Growers Must Use Disease Management Strategies When it Comes to SWD
Dave Jones, Extension Educator with Michigan State University, says growers are well accustomed to monitoring and thinking ahead. Read More
Stone Fruit
July 31, 2017
Clemson Peach Breeding Hones in on Disease Resistance, Flavor
In spite of the March freeze that devastated growers in the region, one producer says breeding for taste and quality needs to prevail. Read More
Disease Control
July 25, 2017
Brown Rot Sinks its Teeth into Michigan Cherries
Unseasonably wet weather causes outbreak, and growers are warned it can spread to peaches. Read More
Stone Fruit
July 6, 2017
Oriental Fruit Moth One Shifty Pest
This moth has many characteristics that have allowed it to adapt and thrive in many peach and nectarine growing regions. Read More
Stone Fruit
July 5, 2017
Floyd Zaiger is the Sweetness Scientist Behind Zaiger Genetics
Floyd Zaiger’s innovative lab extends to the orchard, where he and his kids’ crosses produce some of the world’s most fabulous fruit. Read More
Apples & Pears
June 19, 2017
Bee-ware: New Resources Released for National Pollinator Week
New videos, webinars available during week-long observance. Read More
Stone Fruit
June 17, 2017
Keep an Eye out for Peach Leaf Curl
Follow these tips to prevent the disease next year. Read More
Stone Fruit
June 12, 2017
Monster Sweet Cherry Crop Expected
But the tart cherry crop is forecasted to drop nearly one-quarter from 2016. Read More
Stone Fruit
June 6, 2017
California Dried Plum Crop Expected To Double
After the disastrous 2016 bloom, a more normal crop this year has the prune industry back on track. Read More
Stone Fruit
June 5, 2017
Michigan State University Awarded Grant to Tackle Spotted Wing Drosophila
Research team seeks solutions to protect state’s cherry crop. Read More
Stone Fruit
June 4, 2017
Multiple Leader Training Optimizes Sweet Cherry Labor Efficiency
The final intensive training system to be examined in the North American NC-140 Sweet Cherry Canopy Architecture and Rootstock Trial Read More
Stone Fruit
May 23, 2017
Northeast Peach Crop Rebounds
After a mild winter and relatively uneventful bloom time, the crop is setting up nicely for the region. Read More
peach buds and blossom
Stone Fruit
May 8, 2017
USDA Researchers Say Georgia Peach Crop Worst in 100 Years
Spring freeze, not enough chill hours make for a tough growing season. Read More
Stone Fruit
April 29, 2017
Challenging Cherry Disease Keeps Growers, Researchers on Their Toes
With a few years of experience with more is understood about little cherry disease, however, few unknowns remain. Read More