Apple Talk Conference Call Summary
Tuesday, August 20th, 2013, 8:00 – 9:00
Presenters: John Aue, Threshold IPM.
Moderator: Peter Werts, IPM Institute of North America; questions or comments, .
August 20th webinar audio download: here
Webinar slides available for download:
CC Webinar III, 2013 081913 draft for John
Scab and fungicide resistance
John and Peter are planning a fall grower survey on scab management and fungicide resistance. There is the potential to speak about this topic at the WAGA conference this winter.
Spotted tentiform leafminer (STLM)
Spotted tentiform leafminer is in its 3rd flight this season. Insect-trap counts have been low in recent years and in this third flight counts are up significantly. Spotted tentiform leafminer fly well and could be on neighboring deciduous trees far from the orchard, therefore, males caught in traps may not be representative of the amount of females present in the orchard laying eggs. Track infestations by monitor orchard perimeters for leaf mines. If you have a hard time finding STLM in your orchard this pest is not going to cause an economic concern at this stage of the season.  Please see the link for summer STLM monitoring http://ipmguidelines.org/TreeFruits/Chapters/CH07/default-11.aspx.
Apple maggot
Apple maggot has the potential to be a late-season concern.  Continue monitoring traps through August and into early September.  September flights can be high and may require targeted sprays. Spot sprays were not recommended for apple maggot early in the season, but late in the season it could be an effective approach.  For organic growers Pyganic can be used if you target the application during the day. Pyganic has a zero day pre-harvest interval. Carbaryl (Sevin) can be used by conventional growers and has a three-day pre-harvest interval. Some may choose to not make any applications this late in the game but that will cause potential for economic threat, especially if the apples are stored in bins after harvest. The eggs then have the potential to hatch out and cause more devastation and infest other fruit in the bin.
Woolly apple aphid
Woolly apple aphid populations you are seeing on the tree right now reflect the number that will be overwintering underground this winter. At this point in the season they are not just a nuisance but can be an issue for next season. Check colonies for presence of common aphid predators, including syrphid larvae, assassin bug larvae, and mummified aphids from parasitic wasps. Blow the fluff off a colony to examine for beneficial insects. If chemical treatment is necessary, options are limited, Movento is a registered material with a fairly short pre-harvest interval. The neonicotinoid Imidacloprid (Admire, Alias, and Montana) are inexpensive and may show results.
Bitter pit
Bitter pit is becoming a huge concern and with the dry conditions there is the potential for large economic damage. Don’t confuse bitter pit with stink bug damage. Stink bugs are more likely to be spread more evenly across different areas of the orchard. Bitter pit may be variety specific and not have even distribution. It is not too late to put on more calcium, if you are two weeks from harvest. Irrigating the trees will help the tree with transpiration of available calcium.
Bitter rot
Bitter rot is a fruit rot that begins to show up later in the season and can spread rapidly through orchards. Symptoms include concentric rings defined by orange pustules. Look for it in fruit on the orchard floor that was hand thinned. John is seeing a lot of bitter rot on fruit drops.  Cortland has a lot of mummified fruit and has a higher percentage of larger, ping-pong size mummified fruit and are a fantastic host for bitter rot.  Remove rotted fruit by hand in organic orchards. Using Captan is the primary option because of pre-harvest interval limitations with other products. If we don’t have a rainy fall that Captan residue could stay on the fruit for an extended period.
Differentiating late season Lepidoptera and codling moth damage       Â
At the end of the season it can be challenging to differentiate feeding injury to fruit from the summer generation of obliquebanded leafroller (OBLR). Typical codling moth damage extends to the core of the apple with evidence of feeding of the seeds. Bites that don’t have a hole can be confusing. Apples this season may be ahead of the codling moth. Don’t let your pheromone traps get soaked with water or covered in insects, change them on schedule. Looking at the context is important for differentiating what insect caused the damage. Having reliable traps is a requirement to achieving that context. OBLR have a tiny hole and they are underneath the skin chewing. Two to three small holes is typical of OBLR feeding injury. Early season injury can be evident by a depression late in the season. Damage is not as deep into the fruit if you slice layers into the fruit. Leaf rollers don’t cause a large exit wound like codling moth.
Apple maggot
Apple maggot damage often does not show up in fruit until several weeks after egg laying occurred. Generally, if tunnel damage in the fruit is not well defined, it is likely from apple maggot. Knowing the history of the orchard can be helpful in creating context when trying to pinpoint insect fruit damage. Usually there is more than one oviposition per fruit laying more than one fruit in each apple. Trapping with baited or unbaited red balls makes diagnosing apple maggot easier and is the obvious solution for monitoring. More traps should be hung or relocated to blocks where fruit is getting closer to being fully ripe.
Brown marmorated stinkbugs (BMSB)
The brown marmorated stink bug hasn’t been identified as a nuisance pest in the state of Wisconsin, but its reach is quickly spreading across the east.  There are also more populations of native stinkbugs being recorded in our orchards. Miss identification between the native stink bugs and BMSB can occur. The BMSB is much larger and has a rounded shoulder and black and white banding on their antennae.  In 2012 there were high populations going in to overwintering in the mid-Atlantic region. This pest has a wide host range during the summer months, which keep it out of the agricultural crops. This year, the cool wet summer has lead the BMSB to stay in standing dead trees and other outside hosts.  It is important to manage this pest through harvest and keep in mind that undamaged fruit at harvest can be pulled out of cold storage four to six weeks later showing damage. To differentiate BMSB from apple maggot damage notice the dried out corky appearance. In apple maggot you will notice it is still juicy. Later into the season the damage becomes more severe, it is unclear whether there feeding habits change throughout the season or if it is just overlapping generations that cause the increase in damage. If you suspected injury from BMSB, be sure to contact your local Extension service or John Aue to make sure injury or insect specimens are properly identified.
