2015 Fruit Pest Update

July 1, 2015

CHERRY PEST ALERT 

Spotted Wing Drosophila (SWD) has been caught!!

See cherry section below for latest information on spotted wing drosophila.

While everyone did get some rain today, at the Station it was a bit excessive. Starting just before midnight to about 8 am rain totaled over 2.5 inches here. There was a narrow band of rain about a mile wide, from north to south, that stretched east to west across the peninsula resulting in a very heavy downpour not seen elsewhere on the peninsula. This was in the area almost identical to where last summer’s devastating hail storm occurred. The next two highest rain totals occurred at the Enviroweather sites just north of the station and in West Jacksonport, that saw totals of 1.00″ and 1.35″ respectively. Other sites ranged between 0.1″ and 0.5″ total. Unfortunately, for those of us trying to control apple scab and cherry leaf spot all weather sites are recording yet another infection period.

APPLE

Disease Pressure – Now that we are past apple scab primary season fungicide intervals can be lengthened to 2-3 weeks between protectant fungicides. However apple growers who have scab lesions present in their orchards should be applying protectant fungicides on a tighter schedule to keep leaves and fruit protected prior to any new infection event. Captan continues to be 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 2-3 weeks through the pre harvest interval should keep fruit infections to a minimum.

Insect Pressure – A second application for codling moth 1st generation control should have been made by now, or in the next day or two, on the peninsula. Typically two applications per generation are adequate to control codling moth. There are high pressure orchards that may require a third application. The only way to really know if your orchard is a high pressure one is to use pheromone traps. If these traps continue to catch 5 or more moth per week control applications should continue on a 10-14 day schedule.

CHERRY

Click here for a good article on controlling cherry leaf spot in orchards with existing symptoms from George Sundin MSU

Disease Pressure – Cherry leaf spot continues to be seen in many scouted orchards on the peninsula. The SDHI fungicides Luna Sensation and Merivon are considered to be excellent leaf spot and powdery mildew materials. Both are also good brown rot materials, Merivon the better of the two. Something to keep in mind as we get closer to harvest and as brown rot pressure begins to increase. Insect Pressure –  If a control applications has not been made for plum curculio, be aware of the PCPHI (Plum Curculio Pre Harvest Interval) to keep larva out of the fruit at harvest. Applications should be made no later than 375 degree days base 50ºF after bloom. This means an application should have been made by 6/20 south of Sturgeon Bay, by 6/25 in Sturgeon Bay and on the bay side of the peninsula, and no later than 6/30 lake side (cooler sites). Larva hatching after 375 DD could still be in the fruit at harvest.

CHERRY PEST ALERT 

Cherry fruit fly and spotted wing drosophila (SWD) traps have been placed in cherry orchards throughout the peninsula. A single SWD female was found in a northern door cherry orchard. Once we can confirm SWD at another orchard on the peninsula control applications should be made as soon as possible. Below is a table rating possible control choices for SWD all of which are effective cherry fruit fly materials as well. To this point no cherry fruit fly have been caught. For cherry fruit fly, once they are caught on baited yellow sticky traps, growers have 7-10 days to apply a control.

Trade Name
PHI
Control Rating
0-3 days
Control Rating
7-14 days
Sevin
1 Day
3
4
Malathion
1 Day
1
3
Danitol
3 Days
2
2
Imidan
7 Days
2
2
Delegate
7 Days
2
2
Spintor
7 Days
2
2
Warrior 14 Days 2 2
Control Rating Key: 1=Excellent (90%+), 2= Moderate (90-60%), 3=Low (60-30%), 4=Poor (30-0%)

GRAPE Disease Pressure – Symptoms of both black rot and phomopsis infection have been observed on grapes here at the Peninsular Station. As grapes approach bloom and early fruit development, grape flower and fruit clusters are also 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. Should temperatures begin to rise,  powdery mildew and downy mildew control will become even more critical. Insect Pressure – First generation grape berry moth will soon be emerging (typically just before bloom) from overwintering pupa. Mated females will then lay eggs shortly after (3-6 days after emergence). A control application right after bloom can be very effective in stopping early season feeding on grape clusters. However, early season berry loss can be compensated for by later berry growth, and sprays for these larvae can be delayed until second generation egg laying. The model available on the Enviro-weather web site tracks percent of egglaying and predicts the start of second and third generation egglaying (810, 1620 and 2430 GDD Base 47F from the biofix of wild grape bloom, respectively). To use this model, you need to record the date of wild grape bloom at your location. Check back here for timing of insecticide applications for second and third generation egg laying. Finally, rose chafers have been reported in Door and Kewaunee counties and can be a problem at sandy sites. Another pest to be aware of are potato leafhoppers, and they may start to show up in the coming weeks. They arrive on storms and wind from the south. Control applications for these pests are often not necessary unless infestations are severe.

Links to individual Enviro-Weather stations:

Casco   Southern Door   Sturgeon Bay   Egg Harbor   W Jacksonport   Sister Bay