AppleTalk Conference Call Summary
Tuesday, August 7, 2018, 8:00 – 9:00 AM
Presenter: John Aue, Threshold IPM
Moderator: Peter Werts, IPM Institute of North America; questions or comments, pwerts@ipminstitute.org
August 7th Call Stream: CLICK HERE
Thank you for a successful season of AppleTalk! Your participation makes this program possible. Please keep an eye on your email for information on our annual survey and Apple-a-Day IPM Calendar. We would like to collect your favorite photos from your orchard and bring this calendar to print by the end of November. John Aue and Peter Werts will continue to scout orchards through September and are available to answer questions.
Organic Japanese beetle management with Rami Aburomia
Rami Aburomia operates an organic orchard near Mt. Horeb Wisconsin. We have discussed the new Bacillus thuringiensis insecticide BeetleGone previously on AppleTalk but have yet to receive any feedback from growers on its performance. After hearing about Rami’s experience with BeetleGone, we asked if he would share what he’s learned on this week’s AppleTalk.
Japanese beetle (JPB) injury was concentrated in Rami’s half-acre block of high-density Honeycrisp. In 2017, Rami experienced a lot of damage when trees were in their third leaf. Some trees experienced skeletonizing in the top quarter. Toward the end of the JPB season, he resorted to trapping the beetles just to get them out of the orchard.
Japanese beetles reappeared this year toward the end of June and in early-July. There was a small amount of protection remaining from a Surround (kaolin) application for plum curculio, but once pressure began to increase, Rami sprayed food-grade diatomaceous earth (DE) combined with neem oil via airblast sprayer in early- to mid-July. By end of July, a total of 16 pounds per acre of DE had been applied. Although it’s difficult to compare JPB populations between seasons, the applications of DE and neem oil did appear to reduce injury. Rami applied BeetleGone on July 27th and doesn’t expect to have to reapply since numbers are quite low.
With only one application of BeetleGone, what rate did you use?
Rami used the manufacturer-recommended rate of two ounces per gallon on Honeycrisp and related varieties, which equates to six pounds per acre when applied at 50 GPA. However, five pounds per acre may be more accurate because Rami stretched the spray as far as he could, only treating the top two-thirds of the tree canopy.
When you used 16 pounds per acre of DE, did you apply it with neem? What neem product did you use?
Raw neem oil, i.e., Ahimsa Organics Neem Oil, was applied twice with the DE and Dr. Bronner’s soap as an emulsifier. Raw neem can become too viscous to be pushed through fine screens. Using an AgTec alleviates problems with clogging nozzles. Commercial neem products contain adjuvants that have caused problems with fruit finish and leaf burns. Growers who plan to use a commercial neem product should experiment first to evaluate the risk of phytotoxicity.
Rami used DE instead of Surround because it is only one-third the price and it leaves much less residue. There was much less damage throughout July than what had been experienced in 2017, but It’s difficult to tell if DE or neem was responsible for repelling JPB.
Another organic orchard used three applications of BeetleGone at 2.5 pounds per acre for each application and the grower had been satisfied with the results. This organic orchard has a mixed fruit and vegetable farm, which can result in a more widespread population of JPB. He also does not grow Honeycrisp which are particularly susceptible to JPB. Japanese beetle populations appeared to be more dispersed in the IPM orchards John Aue has visited this season. When we have a population which only focuses on the Honeycrisp, it can reflect outside pressure. Damage in many different parts of these orchards and farms may reflect a more localized or internal population.
How expensive is BeetleGone per pound?
The label recommends applying BeetleGone as a concentration where two ounces per gallon of water is applied, rather than as dilute rate per acre. Fifty gallons per acre applied at two ounces per gallon comes out to about 6.25 pounds. Running about $23 per pound of material, treating one acre would cost around $140. While expensive, this only needs to be applied to varieties that have an existing infestation of JPB. The labeled range of selected rates is one to 17 pounds per acre, which allows for measuring product for applications made with a backpack sprayer. Although the cost is high, the application seemed to decrease JPB populations.
Brown marmorated stink bug status for 2018 harvest
In collaboration with the University of Wisconsin and the Wisconsin Department of Agriculture Trade and Consumer Protection, the IPM Institute has been monitoring brown marmorated stink bug (BMSB) in Wisconsin orchards since 2015. The spread and emergence of BMSB have been tracked, starting with pyramid traps in 2015 or 2016 and later improving to a two-lure trap. Traps are now set at 23 locations with additional traps at the University of Wisconsin Madison and at CSA community farms and gardens.
The pest has a strong preference for apples, but the host range for BMSB extends to tomatoes, sweet corn, peppers, green beans, woody perennials and has over 300 suitable hosts in North America.
This spring, the overwintering generation emerged in May and were caught in traps in several locations. Â The population seems to be reduced from last year, but more detections and reports are coming in statewide, including in Rock, Walworth, Racine and Dane Counties and some orchards on the Illinois border.
All growers statewide should monitor BMSB with a trap or visually along the perimeter and interior of the orchard during harvest. Unlike many of the other apple pests, BMSB does not settle down at harvest. Growers should order and set up traps along orchard perimeters or in the front yard. Putting traps in the middle of blocks is not advised. Based on emergence patterns, we can expect to find this pest in higher numbers in our homes and buildings for about a season before they pose a more serious agricultural risk. Be aware of BMSB in your packing sheds and homes in addition to monitoring in the orchard.
Insecticide efficacy and performance varies greatly across and within different chemical classes. Imidan (phosmet) has performed poorly in bioassays and field trials against BMSB. The best performance against BMSB has been from the older synthetic pyrethroids, e.g., Brigade (bifenthrin). The neonicotinoids have limited efficacy but can be used. Actara (thiamethoxam) has performed the best, however, its use is limited by its 35-day pre-harvest interval (PHI). There are two newer neonicotinoids called Venom and Scorpion (dinotefuran) with a shorter PHI, but these have only been registered for apples under emergency registration exemptions out East. If BMSB became a problem, these materials will likely become registered for growers in the Midwest.
While BMSB is mostly being found in southern Wisconsin, there is also an established population in the Minneapolis/St. Paul area. Growers in the Upper Mississippi River Valley and Eau Claire should have BMSB traps out during harvest. If a BMSB is captured, take a good photo or bring it to your county Extension office.
In addition to monitoring BMSB with traps, growers should scout within 100 feet of the orchard perimeter. When stink bugs find an orchard, they tend to spend several days to a week in the perimeter before moving into the interior of the orchard block. This results in a strong edge effect. When scouting, growers realistically won’t be able to see incision injury from proboscis injury. This will, however, result in a deep cork spot where juice has been sucked out, whereas other insect damage, bitter pit or bruising will be much shallower. When stink bug feeds on an apple, there are often multiple feeding sites. Find more information on distinguishing bitter pit, apple maggot and BMSB damage in MSU’s 2017 article, http://msue.anr.msu.edu/news/look_a_like_late_season_apple_damage.
Another good resource is www.stopbmsb.org. This is a national clearinghouse for all the current research on BMSB.
Insect updates
Codling moth
The second-generation codling moth (CM) flight will continue through the end of August and it is not uncommon for growers to catch CM the first week in September. This is particularly true if CM was a problem last year or if there is a significant outside source. An imbalance between trap catches could suggest an in-house population that wasn’t completely controlled. If CM injury is found on fruit, slice the fruit open to look for larvae. Older damage will be black, moldy and will not have larvae present. John found two large, lethargic fifth-instar larvae that were ready to pupate. These large larvae are still from the first generation and will pupate and fly in two weeks. Continue to monitor CM traps until the end of August even if numbers have begun to decrease.
Not effectively controlling population this fall will lead to a larger populations next spring. If additional insecticide applications are needed for codling moth, make sure to run a degree-day model out to 250 DD from the biofix to accurately time the application. Right now, our hot weather will result in accumulation of 250 DD in ten to 12 days.
Obliquebanded leafroller
In many orchards, obliquebanded leafroller (OBLR) flights have begun. Unlike the OBLR injury to the terminals observed in spring, the summer generation feeds directly on the fruit. This injury is sometimes called “cat facingâ€. Altacor (chlorantraniliprole), Delegate (spinetoram) and Bt products are all good options for managing OBLR. The neonicotinoids generally do not perform as well on OBLR.
San Jose scale
According to reports from the Hudson Valley Research Laboratory in Highland, New York, second-generation crawlers have become visible, which means we are likely approaching that point as well. Growers that read the Cornell Scaffolds Fruit Journal will note that degree-day accumulations at the Highland station are consistent with accumulations in southern Wisconsin. San Jose scale tape can continue to be monitored for the next two-to-three weeks.
For more information on second-generation San Jose scale and nymph emergence, visit: https://blogs.cornell.edu/jentsch/2018/08/06/san-jose-scale-2nd-gen-nymph-emergence-nearing-end-of-codling-moth-larval-emergence-6th-august-2018/.
Apple maggot
If you are still finding apple maggot (AM) in traps, John suggests reapplying an insecticide and hanging more traps. Unbaited-red spheres are not as good at catching AM once the fruit begins to ripen. Late season AM should be treated with an insecticide that is toxic to the adults. A high rate of another neonicotinoid like Assail (acetamiprid) may be a good final effort to induce adult mortality either area-wide or as a spot treatment. Exirel (cyantraniliprole) can also be used at a minimal rate of 17 ounces, which can be expensive if CM and OBLR do not also need to be controlled late-season.
Disease updates
Fruit rots
When scouting fallen fruit, look for black, brown, purple or pink lesions on the fruit. Soft spots without fruiting bodies mean no rots are present since the infection would have had plenty of time to sporulate. Growers should look for the pink fruiting bodies of bitter rot after rain events.
Bitter rot exudes an orange, slimy mass that is almost salmon-colored. Black rot and white rot make black fruiting bodies but do not make orange slime. Bitter rot also has a sharper V-shape into the fruit than black and white rot. Fruit infected with bitter rot are often observed in groupings and clusters on several branches. While bitter rot does not cause big cankers, it can infect quickly. Rotten fruit tends not to decay very well on herbicide strips.
