West central Michigan tree fruit update – April 11, 2023

Emily Lavely<lavelyem@msu.edu>, Michigan State University Extension - April 11, 2023

While there was little change in buds over the past week, bud break is expected for fruit crops in the west central region this week as warmer weather comes.

Figure 1. Stage of tree phenology for apple, peach, cherry, plum and pear in Oceana County on April 10, 2023. Photo by Emily Lavely, MSU Extension.

Weather update

In west central Michigan, last week was cooler overall and buds stayed at a similar stage for tree fruit; however, temperatures have gradually been increasing over the past week. As of Monday, April 10, the Hart Enviroweather station reported an accumulation of 81.5 GDD₄₂and 22.8 GDD₅₀. A warmup this week will lead to changes in tree phenology and bud break for tree fruit crops.

Growing degree days (GDD) for base 42 and base 50 will almost double over the coming week with highs predicted in the mid to upper 60s degrees Fahrenheit and lows in the 40s F and 50s F over the next few days. Temperatures will cool down over the weekend with highs in the 40s F and lows in the 30s F with the potential for precipitation.

Fields have dried down this week, and growers continue to prune dormant trees, plant new blocks, chop brush, and complete other spring orchard tasks.

Table 1. Current and five-year average degree day accumulation for the west central region as of April 10, 2023.
Station	2023 GDD base 42 F	5-yr avg GDD base 42 F	2023 GDD base 50 F	5-yr avg GDD base 50 F
Benona/Shelby	55	69.5	14	21
Elbridge/Hart	64	84.7	18	28.3
Fremont	69	96.3	18	32.9
Grant*	76	103.9	21	37.3
Hart	73	83.5	22	27.7
Ludington	65	80.2	18	26.8
Mears	69	119.5	20	43.3
New Era	60	113.1	15	37.9

Weather data was gathered from Enviroweather. Watch a full weather update from Jeff Andresen, MSU climatologist.

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

Minimal changes in bud development occurred over the past week (Figure 1), but buds are expected to respond readily to warmer temperatures this week.

Crop update

Apple varieties in Oceana County range from dormant to silver tip phenological stages. Early varieties such as Zestar and Idared are showing signs of bud swell and green tip, but most buds remain dormant in the region for varieties like Gala, Jonagold and Honeycrisp. As a reminder, silver tip in apple is 101 GDD base 42 F for McIntosh based on over 30 years of observation from Sparta, Michigan. Other apple varieties will be ahead or behind McIntosh. Hart is at 73 GDD base 42 F. Many varieties may be at green tip by the end of the week.

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 showing signs of bud swell and side green. 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 in the next week.

Some plums and apricots are showing signs of bud swell side green.

Pear varieties are dormant or at bud swell. Dormant applications of oil can still be applied to help suppress psylla and San Jose scale populations.

Pest and disease update

With warmer conditions, pest and disease activity will begin shortly in the west central area orchards. Pear psylla adults and eggs were observed at the West Central Michigan Research and Extension Center on April 10. Scale was also observed this week on plum trees (Figure 2). As a reminder, if growers are seeing scale, dormant sprays are important to manage this pest. Scale seems to be more prevalent in recent years, so it is important for growers to scout to determine if it is present in the orchard.

Figure 2. Scale insects found on a plum tree in Oceana County on April 10, 2023. Photo by Emily Lavely, MSU Extension.

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, MI, trapped an average of 2.3 adult green fruitworm (GFW) this week, but green fruitworm is not a major pest in our area.

If growers have not applied dormant or delayed dormant sprays such as oil or copper, they should do so shortly. No disease concerns have been reported for our region at this time.

Pests to start thinking about include:

Black stem borer
Green fruitworm
Pear psylla
Redbanded leafroller
Spotted tentiform leafminor
Oblique banded 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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