2016 Fruit Pest Update

SWD ALERT!

Trap catches of spotted wing drosophila continued to increase this week and are skyrocketing in  orchards post harvest. Counts in orchard interiors (7.8/trap) and in orchard edges (5.3/trap) remain above the critical >3.0/trap level. Traps at these levels last season were often associated with larva in the fruit. We continue to see very few detectable larva in fruit sampled from sprayed orchards; however, samples from unsprayed and post harvest sampled orchards contain increasing numbers of live larva. To keep populations low and reduce the incidence of detectable damage, continue control applications through harvest on a 7-10 day FULL COVER application schedule.

Michigan SWD Management Guide Link.

July 28, 2016 – This past week all weather stations on the peninsula recorded one or two infection periods for apple scab (on the 14th, 15th and/or 17th). For cherry leaf spot, single infections occurred in Southern Door (14th), Sturgeon Bay (15th), and Sister Bay (15th). In grapes, black rot infection occurred only in Egg Harbor on the 14thCodling moth trap catches remain high in some apple orchards. Where this is the case, control applications should continue where catches remain above threshold (5-7 plus moths caught/week). Control for SWD on cherry should continue through harvest to prevent infestation.

APPLE

Disease Pressure – Apple growers can begin to increase intervals between protectant fungicides, as primary apple scab season is now over. Length of application intervals can now be between 2-3 weeks if scab lesions are not present on this year’s leaves or fruit. Apple growers who have scab lesions present in their orchards should be applying protectant fungicides on a regular schedule. Captan is the fungicide of choice when protecting fruit from secondary scab infections. In cases where early control has not been adequate and numerous scab lesions are present, we have been successful in stopping further spread with two applications of Scala fungicide at 10 oz/acre 10 to 14 days apart. After that, a regular program using Captan every 14 to 21 days through the pre harvest interval should keep fruit infections to a minimum.

Insect Pressure – In orchards where codling moth trap catches remain greater than 5-7 moths per week, additional control applications for this pest should continue on a 10-14 day schedule. Assail, Imidan and Exirel are all good choices for this time of the season. These products will also control apple maggot as it has begun to be caught in scouted orchards on the peninsula. If you are not trapping with yellow sticky cards for this pest, it is advisable to begin control treatments on a regular schedule through the end of August.

CHERRY

Disease Pressure – Evidence of new cherry leafspot infections continues to be minimal. This is likely due to the more frequent application of fungicides along with  SWD controls that are being made this season. Brown rot pressure is high with ripening cherries, hot and humid conditions, and bruised fruit caused by wind whip during the recent storms. The SDHI fungicides Luna Sensation and Merivon are considered to be excellent for control. Both are also very good leaf spot and powdery mildew materials.

Insect Pressure – Until harvest, cherries should continue to be protected from spotted wing drosophila infestation (control options for SWD are in the table below). Trap catch numbers have trended up considerably the past two weeks in scouted orchards, especially in the traps placed on orchard edges.  We have yet to see live larva in fruit samples from sprayed orchards, although numerous larva have been found in unsprayed cherries from around the peninsula. To this point in the season, we have caught very few cherry fruit fly in scouted orchards traps. Control applications being made for SWD are likely keeping their numbers down.

Spotted Wing Drosophila Control Options

Trade Name  Class PHI Effectiveness Rating 
Sevin Carbamate 1 Day Good (5-7 days)
Malathion OP 3 Day Good (3-5 days)
Exirel Diamide 3 Day Excellent (7 days)
Danitol Pyrethroid 3 Days Good (7 days)
Imidan OP 7 Days Excellent (7 Days)
Delegate Spinosyn 7 Days Excellent (5-7 days)
Entrust Spinosyn 7 Days Good (3-5 days)
Mustang Maxx Pyrethroid 14 Days Excellent (7 days)

Control Rating Key: 1=Excellent (90%+), 2= Moderate (90-60%), 3=Low (60-30%), 4=Poor (30-0%). It is highly recommended that the above controls be rotated for resistance management. A single application of an insecticide of any class should be followed by application of another class. 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, Delegate, or another non-pyrethroid. This pest has short generations time (7-21 days) and by rotating classes regularly, we avoid exposing consecutive generations to the same chemistry.

PARS Trap & SWD Infestation Thoughts – The high SWD trap catches seen at the research station last week are likely due to the small block size of our orchards. This makes the ratio of fence row/alternate host area to orchard very high. Since the alternate host areas were unsprayed, it is apparent that the traps we have set in our orchards had been drawing flies from outside where there could be very high populations; much more so than in larger commercial plantings. Currently we are making control application to the fence rows, as well as our orchard blocks. For now, this strategy appears to be reducing the high traps catches and eliminating the infestation of cherries on the station.

For more information on control of SWD in cherries, click the following link: Michigan SWD Management Guide Link.

Door Peninsula Area Spotted Wing Drosophila Trap Catches 2016      (all reported totals below are from orchard interior traps)

Location
1st Catch 
Crop
Weekly Catch      (7/17-7/23)
Weekly Catch   (7/24-7/30)
Season
Total
Kewaunee Co. South
7/22
Grape
5
5
Kewaunee Co. North
7/22
Raspberry/Apple
6
6
Southern Door West
6/10
Cherry
6
9
25
Southern Door East
6/17
Cherry
7
12
22
Sturgeon Bay Station
7/14
Balaton Cherry
19
12
176
Sturgeon Bay Station
7/14 Montmorency Cherry
2
0
26
Egg Harbor
7/22
Raspberry
9
10
19
Egg Harbor
6/24
Cherry
7
15
28
Sister Bay
6/21
Cherry
0
16
18

GRAPE

Disease Pressure – Symptoms of both black rot and phomopsis infection have been observed on grapes here at the Peninsular Station. Grape fruit clusters are now susceptible to infection from powdery mildew, downy mildew, and latent infections of botrytis. Now is the time to apply protectant and systemic fungicides with activity against all of these diseases. As temperatures have increased powdery mildew and downy mildew control are even more critical.

Insect Pressure – Japanese Beetles and rose chafers have been reported in Door and Kewaunee counties. Click here for more disease and insect information regarding grapes here in NE Wisconsin and around the state from the ‘Wisconsin Fruit News’.

Links to individual Enviro-Weather stations:

Casco   Southern Door   Sturgeon Bay   Egg Harbor   W Jacksonport   Sister Bay