West central Michigan tree fruit update - April 9, 2024

Warmer weather over the past week has advanced bud development for fruit crops in the west central region. Primary scab season is underway.

for decorative purposes.
Figure 1. Stage of tree phenology for apple, peach, sweet cherry, tart cherry, pear, apricot and plum in Oceana County on April 8, 2024. Photo by Emily Lavely, MSU Extension.

Weather update

In west central Michigan, warmer temperatures covered the region and buds continued to swell and advance to the next phenological stage. Temperatures have gradually been increasing over the past week with highs reaching the low 60s degrees Fahrenheit on April 8. Nighttime temperatures have ranged from low 30s to mid-40s. Day and nighttime temperatures are predicted to be moderate with highs in the 50s and lows in the upper 30s and mid-40s. Temperatures will continue to be warmer over the next few days. As of Monday, April 8, the Hart Enviroweather station reported an accumulation of 149.2 growing degree days (GDD) base 42 and 47.7 GDD50. Warmer spring weather this week will lead to continued changes in tree phenology and bud break for tree fruit crops.

Growing degree days for base 42 will increase by about 35 units, and GGD will increase by about 10 units at base 50. Temperatures will cool down over the weekend with highs in the 40s and lows in the 30s with the potential for precipitation. More rain is forecasted for Thursday, April 11.

Maximum soil temperatures since April 1 have ranged from 45 – 54 F at 2 inches soil depth at the Hart Enviroweather station according to the weather forecast. At 4 inches soil depth, maximum soil temperature ranged from 43 – 50.9 F. This is the temperature when roots start to become active and are able to take up water and nutrients. Most fine roots that actively take up water and nutrients are in the top 0.5 – 2 feet of soil depending on the rootstock.

Soil moisture at 4 inches soil depth went up to 19.2% after the April 2 rain event, which is the highest it has been over the past few weeks. Soils have now dried down to about 11% at 4 inches. At soil depth of 20 inches, soil moisture content has hovered around 10% for Hart.

Fields have dried down this week after rain events from April 1 – 4 and April 7. Growers continue to prune dormant trees, plant new trees, chop brush and complete other spring orchard tasks.

Watch a full weather update from Jeff AndresenMichigan State University Extension climatologist.

More information and reports on normal weather conditions and departures from normal can be found on the NOAA Climate Prediction Center websiteNOAA U.S. Climate Normals websiteNOAA Climate Normals Quick Access Page (which may be searched by region) and Midwest Regional Climate Center website.

Crop update

Early bud development continued over the past week with bud swell and some green tissue showing (Figure 1).

Apple varieties in Oceana County range from silver tip to green tip for phenological stages. Early varieties such as Zestar and Idared are at green tip, and in Hart, varieties such as Gala, Jonagold and Honeycrisp are at first green. As a reminder, first green in apple is 127 GDD base 42 F for McIntosh based on over 30 years of observation from Sparta. Other apple varieties will be ahead or behind McIntosh. Hart is at 149.2 GDD base 42 F.

Tart and sweet cherry buds range from bud swell to side green. If growers have not done so yet, there is still time to apply dormant or delayed dormant applications of oil or copper sprays to manage bacterial canker and early pests such as mites or scale.

Early peaches are at the swollen bud stage. Venture peach buds are at bud swell at the West Central Michigan Research and Extension Center in Hart. If growers have not already applied a spray for peach leaf curl, an application for final spring dormant sprays using copper products for management of peach leaf curl and bacterial canker is warranted this week.

Some plums are at bud swell and side green, and apricots are at pink with a few blossoms starting to open. At bloom, plum and apricots are susceptible to brown rot. Fungicides should be applied during bloom if warm (greater than 64 F) rains are predicted, especially in orchards where inoculum levels are high. Fruit are very susceptible to infection up to three weeks after shuck split.

Pear varieties are at bud swell or bud burst. Dormant applications of oil can still be applied to help suppress psylla and San Jose scale populations. Bartlett pear at the West Central Michigan Research and Extension Center are at bud swell.

Pest and disease update

Primary scab season has begun. First scab spores were detected after the rain event from April 1 – 4 with four spores per rod. For the rain events on April 5, 13 spores were detected per rod, and for April 7, 3.5 spores were detected per rod. With warmer temperatures over the past few days, more ascospores will have reached maturity. Expect a large spore release with the next rain event and medium scab pressure. Rain is expected for Thursday, April 11, so be sure to protect new tissue before then.

With warmer conditions, pest and disease activity will begin shortly in west central area orchards. Pear psylla adults and eggs were observed at the West Central Michigan Research and Extension Center on April 8. As a reminder, dormant sprays are important to manage scale. Scale seems to be more prevalent in recent years, so it is important to scout to determine if it is present in the orchard.

I will be regularly monitoring common orchard pests and initial apple scab infections periods over the coming weeks. The trapline at Trevor Nichols Research Center in Fennville, Michigan, trapped an average of 2.3 adult green fruitworm this week. Expect green fruitworm to be in our area shortly.

If growers have not applied dormant or delayed dormant sprays such as oil or copper, they should do so shortly.

Pests to start thinking about include:

  • Black stem borer
  • Green fruitworm
  • Pear psylla
  • Redbanded leafroller
  • Spotted tentiform leafminer
  • Obliquebanded leafroller
  • Climbing cutworms
  • San Jose scale
  • European red mite

For more information about regional reports, please visit the Michigan State University Extension website.

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