Fruit Crop Pest Report- July 15, 2019

2019 Fruit Pest Update

July 15, 2019

2019 – 2020 Midwest Fruit Pest Management Guide

Spotted wing drosophila are active- female flies were first caught last Tuesday in Southern Door and numbers have greatly increased throughout the week. They have now been caught in multiple blocks south of Egg Harbor. Trap counts can be found at this link and will be updated often: https://peninsular.ars.wisc.edu/apple-cherry-pest-update/

Early sweet cherry harvest will be starting this week and tart cherries are a couple weeks from harvest. Grapes are at buckshot stage to bunch-closure.

For all tree fruit crops, if you plan to take leaf samples for tissue testing, late July to early August is the best time. Take 50-100 leaves from several trees that are representative of that block and put them in a paper bag before sending them to a tissue analysis lab.

Overall, July has been very dry. Most Enviroweather Stations around the region, reported less than ½” rain this month, with the Sister Bay station reporting only 0.18” total. Rainfall totals from this morning varied greatly throughout the county, with 4-5” reported in Sturgeon Bay, but only a trace of precipitation in Casco/Luxemburg.

NOTE: The Enviroweather Stations are going through an upgrade, so you might see some temporary outages over the next week or two. We are working to get them back online as quickly as possible.

Below is a degree day comparison of the last five years.

Date 7/15	2015	2016	2017	2018	2019	5 yr avg
Base 50	769	919	833	1070	739	870

INSECT & DISEASE CONTROL

APPLE

Disease Pressure – Apple growers can begin to increase intervals between protectant fungicides now as primary apple scab season is over. Length of intervals can be increased to 2-3 weeks if scab lesions are not present on leaves or fruit. Apple growers who have scab lesions present in their orchards should continue to apply protectant fungicides on a regular schedule. Sooty blotch and flyspeck pressure will likely increase this week, with predicted temperatures in the 80s and today’s rain (see article from the Wisconsin Fruit News at the end of this report). Fireblight continues to have the potential for infection if there is hail or damaging winds.

Insect Pressure – Trap catches for 1^st generation codling moth flight continue to be moderately high and over threshold in pheromone traps in some scouted apple orchards. If you are still seeing high trap catches (greater than 5-7 moths per week) additional control applications may be necessary for this pest. Yellow sticky cards for monitoring apple maggot should go out into orchards this week. Once a first fly is caught, traps can be switched to red sphere traps, which are more effective as females look for egg-laying sites on ripening apples. (click here for a newer publication on Apple Maggot). Spotted tentiform leafminer adult flight is strong right now. Keep an eye out for European red mites, as numbers have the potential of increasing with warm temperatures and infrequent rain events (except today). Growers should continue scouting the undersides of leaves to determine if control applications are necessary. The July mite threshold is an average of 5 mites per leaf. No brown marmorated stink bugs have been caught.

CHERRY

Disease Pressure – Cherry leaf spot pressure remains very high and it is important to stay on a tight spray schedule. Secondary infections are going to continue to be a threat especially in blocks that did not have good early control. Some powdery mildew is showing up in more sheltered blocks, with less airflow. American brown rot is showing up in some blocks on immature fruit that didn’t June-drop. If you see this in your orchard, make sure your fungicides include this disease on their label.

Insect Pressure – SWD is active and are already quickly increasing in numbers. This will likely continue as we approach harvest, since they can reproduce quickly. Growers are advised to use a 7-day, full cover control, now through harvest. The most affordable and effective controls for SWD are Imidan and Mustang Maxx (among other pyrethroids). It is highly recommended that these controls be rotated for resistance management. For example, if Mustang Maxx is applied, the next application, 7 days later, should not be a Mustang Maxx or any other pyrethroid, but Imidan. This pest has short generations time (7-21 days) and by rotating classes regularly we avoid exposing consecutive generations to the same chemistry. (Reach MSU’s most recent SWD management guide, here).

NOTE: Please be aware of re-entry intervals (REI), especially for pick-your-own harvesting and Pre-Harvest Intervals (PHI). Mustang Maxx is still under a Section 24(c) Special Local Need label through the end of 2020, allowing for a 3 day PHI, FOR TART CHERRY ONLY (more info here).

No cherry fruit fly have been caught. Once cherry fruit fly become active, an insecticide should be applied within one week of a catch on yellow sticky traps. Continue to scout for European red mites, especially in blocks where there has been a lot of use of pyrethroids for SWD control in the past few years.

GRAPE

Celebrate the first Wisconsin Vineyard Week by coming to the Peninsular Agricultural Research Station Vineyard Walk! Please RSVP to Anna Maenner with the WGGA or to the Door County Extension Office, 920-746-2260.

Disease Pressure – Continue to monitor for diseases, and apply fungicides on a 7-10 day schedule. If bunch rot has been an issue in the past, an early fungicide now, while fruit clusters are still open, can help combat this disease.

When scouting for diseases, former UW graduate student, Dave Jones, made an excellent photo disease guide per variety that can be found here: https://fruit.wisc.edu/wp-content/uploads/sites/36/2017/04/Photo-guide-diseases-cold-climate-grape.pdf.

Insect Pressure – Rose chafer are showing up in the vineyard block at the Peninsular Station. These beetles are most common in sites with sandy soil and the adults will remain active for three to four weeks. Here is a link to an article from Michigan State about controlling rose chafer: https://www.canr.msu.edu/news/rose_chafer_management_for_vineyards. Japanese beetle are becoming active in the Southern parts of the state, but haven’t emerged yet here.