A Parade of Worms: Leps and AM Driving Apple Pest Management

In the Mid-Hudson Valley of NY the Obliquebanded Leafroller, OBLR and Codling Moth (CM) drive the insect pest management program from the middle of June into mid-July. Behind the headliner this week is a parade of lepidoptera and Apple Maggot that if left unattended to will cause varying degrees of infestation, feeding injury and fruit loss this season. These include Oriental Fruit Moth, Red Banded Leafroller, Lesser Apple Worm, Tufted Apple Bud Moth, Sparganothus Fruit Worm, Spotted Tentiform Leafminer, Apple Leafminer, Dogwood Borer…..the list goes on.

Although many of these continue to be present and have the capacity to cause injury to tree fruit, the majority, with the exception of DWB, do not require specific management plans only IF CM and OBLR are managed effectively. DWB will require specific management plans.

We continue to capture very high OBLR adults in our pheromone traps ((2015 Scouting Report)). The first summer brood of OBLR larvae have emerged beginning in mid-June in the Hudson Valley and will complete their development in late July through early August depending on weather (heat units). If you have completed two applications of effective insecticide applications at 14 day intervals beginning at first hatch, you have managed this insect. However, if you are waiting to scout for the insect, varying life stages of immature to mature larva will be present in blocks where management has yet to occur.

Scouting: Leaf injury by all broods is characterized by the larvae rolling leaves and feeding on surrounding foliage and fruit, often accompanied by webbing between leaves or fruit and foliage.

Foliage: Examination of the tops of the trees focused on terminal branches on a blue sky backdrop will show feeding signs in the tattered edges and holes in center of leaves. If you use IPM damage thresholds for management decision making, using the OBLR Sampling Form for foliar assessment to provide a threshold for management based on orchard survey for OBLR damage.

Fruit: Sampling 1000 fruit per block should be conducted bi-weekly to determine first feeding injury. As the larva reach later instar stages in July, break open clustered fruit of Cortland, to find webbing of foliage onto fruit especially on spur Red Delicious and Macoun.

From my observations, singled fruit are less susceptible to OBLR injury in light to moderate infestation levels.

Control: Management of the OBLR during the 1st summer generation is best at early hatch (based on pheromone trap capture applying the 340DD 50F developmental model). Two applications @ 14d intervals beginning at 1st hatch provides >28 days of weather dependent protection during OBLR emergence. The spinosin product Delegate, and the Diamides Belt and Altacor, hold up very well to weathering, providing excellent control of codling moth and OBLR. However, 2″ of rain on the best of products will require reapplication for control during emergence.

Management upon reaching IPM threshold should employ very efficacious materials (Cornell Guidelines: Management Tools).

The first apple maggot (AM) was observed in traps on Thursday, 2nd of July. (2015 Scouting Report). Monthly rainfall accumulations in June exceeded 7 inches has provided ideal conditions for adult fly emergence from the soil this season. Early maturing varieties such as Ginger Gold, Cortland, Red and Golden Delicious (early sweet or low acid varieties) will be most attractive for the first maturing female flies to begin egg laying over the next few weeks. Varieties based on susceptibility to AM.

Apple maggot flies will over winter in a pupal stage in a brown oblong case (puparium) a quarter-inch in length within two inches of the soil surface. The 19th century orchardist would disk beneath their trees to distroy the pupal stage on AM. They emerge from the soil harboring the insect during the last two seasons infested fruit. They have the capacity to migrate for at least half a mile into conventionally grown orchards and previously uninfested blocks, often from neighboring unsprayed orchards or abandoned apple trees. They remain active into September requiring management in late August for residual activity to manage late fly emergence. During the early stage of adult development (7–10 days) the feed on bird droppings and aphid honeydew to obtain nitrogen and sugars to reach sexual maturity.

Scouting: Recommend placement is for three volatile-baited sphere traps per 10- to 15-acre orchard block in early maturing varieties, should begin today if this hasn’t yet been done. Situate red sticky spheres with attractive volatile baits on the outside row towards woods or abandoned apple. Check traps are periodically checked to get a total number of flies caught; dividing this by 3 gives the average catch per trap, and a spray is advised when the result is 5 or more. Discerning AM flies from walnut and cherry fruit fly is critical to avoid ineffective management.

Management: Threshold of mean trap captures of 5 adults per trap per block should be used as the trigger for management.

2014 HVRLab Efficacy Report on Harvest Data for McIntosh (Pg 14) and Ginger Gold (Pg 15)

Recent research conducted in 2010 by Harvey Reissig and Dave Combs provides efficacy data on new insecticides.