2015 Fruit Pest Update

July 21, 2015

 

Spotted wing drosophila, cherry fruit fly, and apple maggot fruit fly have now been caught in cherry orchards in all areas on the peninsula. Because of the zero tolerance for larva in the fruit at harvest, growers that are not using yellow sticky traps in their orchards should consider applying at least one insecticide prior to harvest. Apple maggot have also been caught since late last week in apple orchards on the peninsula and will necessitate control applications.

APPLE

Disease Pressure – Last week 2-3 apple scab infection periods were recorded at all weather locations on 7/13 & 17. This should be a concern for growers with orchards that currently have or had scab present on leaves or fruit earlier this season.  These growers should be applying protectant fungicides on a tighter schedule to keep leaves and fruit protected prior to any new infection events. Captan continues to be the fungicide of choice when protecting fruit from secondary scab infections.

Insect Pressure – As was the case last week, a few orchards continue to see above threshold catches of codling moth 1st generation female moths. These high pressure orchards may require continued control applications on a 10-14 day schedule. The only way to really know if your orchard is a high pressure one is to use pheromone traps. If traps continue to catch 5 or more moth per week, control applications should continue on a 10-14 day schedule. Apple maggot  has now been caught at a number of orchards on the peninsula and will need control applications no later then the end of next week. The choice of control materials at this time should rate good to excellent for both codling moth and apple maggot as they will be the main pest concern for the next month. These include Imidan, Assail, Exirel, Delegate, Voliam Xpress and Voliam flexi.

CHERRY

Disease Pressure – Cherry leaf spot has been less noticeable in many scouted orchards as growers have stepped up their control programs. Brown rot will become more of an issue as we go through harvest, especially with the warmer temperatures that we are experiencing. Some older sterol inhibitor fungicides like Indar and Orius still provide good control of this disease and as long as they are tank mixed with captan, they should provide good leaf spot control. The SDHI fungicides Luna Sensation and Merivon, excellent leaf spot and powdery mildew materials, are also good brown rot materials–Merivon the better of the two. Rotating either of these fungicides with the  sterol inhibitors would be a good strategy as we get closer to harvest and as brown rot pressure begins to increase. Powdery mildew has shown up at very low levels in a few orchards.

Insect Pressure –  Cherry fruit fly and spotted wing drosophila (SWD) have both been caught  on the peninsula. Female SWD have been caught at a number of sights from north to south, but have remained at very low levels and probably do not pose a threat of infesting fruit for most cherry growers. Cherry fruit fly adults have been caught along with apple maggot in cherry orchards in all parts of the peninsula. Although it is not very common to see apple maggot on traps in cherry, as they normally emerge later in the season, they can infest cherry and pose a threat. The last week has seen an increase in cherry fruit fly numbers and because of the zero tolerance for this pest at harvest, growers should consider applying at least one insecticide prior to harvest.  A number of options for fruit fly control that will also control SWD are listed in the table below.

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

GRAPE

Disease Pressure – Recently symptoms of powdery mildew and, especially on very susceptible varieties, downy mildew on grape leaves and fruit clusters have become common. Symptoms of both black rot and phomopsis infection were observed earlier on grapes here at the Peninsular Station, but have not spread much since then. Continue to apply protectant and systemic fungicides with activity against all of these diseases.

Insect Pressure – Very little insect activity has been observed on grapes recently.  Potato leafhoppers are present on some varieties but have not yet caused worrisome damage. Control applications for this pests are often not necessary unless infestations are severe.

Links to individual Enviro-Weather stations:

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