Fruit Crop Pest Report — May 28, 2019

2019 Fruit Pest Update

May 28, 2019

Click for link to

2019 – 2020 Midwest Fruit Pest Management Guide


The warm temperatures this weekend gave a slight indication that summer is coming! But it looks like it’s going to be wet and cool again this week. There was a light to moderate apple scab infection period at all weather stations in Door and Kewaunee County from the rain over Memorial Day into today. Symptoms from any infections that may have occurred would be apparent in about 7-10 days.


Apples at the station are at pink to king bloom in most blocks. Cherries are at full bloom in the northern part of the county and at petal fall in the southern regions. Grapes are still very slowly developing. There appears to be significant winter injury, so it will be important to continue to monitor them as buds break.


Below is a degree day comparison of the last five years. We are still about a week behind average.

Date 5/28 2015 2016 2017 2018 2019 5 yr avg
Base 50 217 204 142 277 103 197




 Disease Pressure – Apple scab spray programs should be ongoing to protect apple scab susceptible varieties through the end of primary scab season; typically mid to end of June in Northeast WI (it likely will be a bit later this year).

As we approach bloom, fire blight will become a concern. Right now temperatures are not conducive to the development of this bacterial disease, but once blossoms open, and if temperatures rise into the 60’s or higher, bacteria will develop quickly. Any wetting (rain, fog or dew) can then trigger an infection. Protectant applications of a bactericide should be made every 4-5 days during the bloom period.

Insect Pressure – So far there haven’t been any plum curculio or codling moths caught in traps. Continue to scout for green fruitworm and obliquebanded leafroller damage through petal fall as there has been some light blossom feeding being observed.  There was a slight spotted tentiform leafminer flight observed last week. Blocks with high levels of rosy apple aphid or tarnished plant bug damage last year should consider an insecticide application at pink.



Disease Pressure – – Orchards with a history of European Brown Rot may need  fungicide applications to prevent infection throughout the bloom period. Cool, wet weather favors this disease, so it has the potential to be an issue this year. Cherries are now susceptible to cherry leaf spot, so fungicide programs should be ongoing.

Insect Pressure – So far there haven’t been any plum curculio adults or spotted wing drosophila flies caught in traps. Continue to scout for green fruitworm and obliquebanded leafroller damage through petal fall.



Mark your calendar for July 18, 3-5pm, for the 2019 Vineyard Walk at the Peninsular Ag Research Station!

Disease Pressure – Little to worry about because of plant stage

Insect Pressure – As buds begin to swell, keep an eye out for grape flea beetle damage (see WI Fruit News article in Issue 2 at the link below).


Wisconsin Fruit News:  *New issue this week*

WFN-Vol 4, Issue 4 (May 24, 2019)

  • Risks and benefits of reducing herbicide rates
  • Winter damaged blueberries
  • Eastern berry thrips
  • Bitter pit management
  • Door County Report


WFN–Vol 4, Issue 3 (May 10, 2019)

  • NEWA new weather monitoring partnership
  • Malusim app released
  • Insect diagnostic lab update
  • Controlling mites in berries
  • Impact of rain on fungicides
  • Blossom thinning


WFN — Vol 4, Issue 2 (April 26, 2019)

  • New fact sheets
  • Insect diagnostic lab update
  • Stocking densities of bees for berry
  • Cranberry degree day
  • Grape developmental stages
  • Flea beetles are here
  • Impact of last winter on apple diseases
  • Managing San Jose scale in apple
  • Pollen tube growth model


WFN — Vol 4, Issue 1 (April 12, 2019)

  • NEWA weather stations
  • Insect Diagnostic Lab update
  • Berry Spring insects
  • Cranberry degree day insecticide trials
  • Grape Flea Beetle
  • Promoting branching apple trees
  • Prebloom fertility apple trees
  • Dog wood borer mating disruption


Links to individual Enviro-Weather stations:


Kewaunee/Stangelville    Kewaunee/Casco 

Southern Door/Nasewaupee   Southern Door/Sturgeon Bay

Sturgeon Bay   Egg Harbor

W Jacksonport   Sister Bay