West central Michigan tree fruit update – July 23, 2024
Print
EmailTart cherry harvest is wrapping up. Harvest of early summer peaches and plum varieties has begun.
Weather update
Over the past week, high temperatures have ranged from the low 70s to low 80s. Low temperatures have ranged from the low 50s to mid-60s, according to the Hart Enviroweather station. Temperatures will be similar for the rest of the week with highs in the low 80s and lows in the 50s and 60s. Conditions have been dry over the past week, and relative humidity ranged from 64 – 74%. Relative humidity will be similar through the end of the week with a slight increase following predicted rain events forecasted for July 23 in the evening and into July 24 in Hart. Based on the Hart Enviroweather station for July 22, current degree-day (DD) accumulation is 2,168 DD42 and 1,324.6 DD50.
Over the past week, soil moisture is lower than it has been all season, according to the Hart Enviroweather station, and ranged from 5 – 9% at 4 inches deep in the soil profile and 5 – 7% at 20 inches soil depth. Irrigation may be needed this week, especially for young trees and high-density plantings.
Soil temperatures at a depth of 2 inches have ranged from the 70s into the low 80s. High soil temperatures can inhibit root activity and cause stress. Soil temperatures at 4 inches deep have been in the 70s over the past week. Deeper in the soil profile, temperatures fluctuate less and have been in the low 70s and upper 60s at 8 and 20 inches deep. Ground cover and higher soil moisture content from rain or irrigation help keep soils cooler which could enhance root and soil microbial activity in the soil. Information and recommendations for irrigations can be found at:
- Apple Irrigation Model | NEWA (cornell.edu)
- Drip Irrigation for Tree Fruit Orchards in Pennsylvania (psu.edu)
Weather data was gathered from Enviroweather.
More information and reports on normal 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.
Crop update
Apple trees are growing well and have produced many new shoots (Photo 1) this season as a result of consistent rain. Fruit are starting to size for early varieties and rang in size from 72 – 82 millimeters (mm) for Zestar and 65 – 70 mm for Idared. Honeycrisp fruit ranged from 67 – 74 mm. Gala fruit were 56 – 60 mm, Jonagold were 64 – 68 mm and Minneiska were 70 – 75 mm in Hart.
Tart and sweet cherry harvest is finished for many growers in the region. Post harvest sprays will be needed to continue to protect leaves from early defoliation from cherry leaf spot and powdery mildew. For cherry leaf spot, leaves typically fall from branches a few weeks after they begin to show disease symptoms. Due to wet weather this season, cherry leaf spot is very common throughout the region. In research blocks at the West Central Michigan Research and Extension Center, there is considerable leaf drop.
The goal for cherry leaf spot management is to maintain a healthy canopy with about 50% of leaves remaining on leaves through mid-September. Maintaining a health canopy supports the tree as it continues to photosynthesize and store carbohydrates to survive the winter. Applications of captan mixed with copper may be the most effective management options for cherry leaf spot. As a reminder, application of copper with high temperatures can lead to phytotoxicity. Do not spray copper products with temperatures above 80 degrees Fahrenheit for several days. Continue protecting leaves from rapid cherry leaf spot infection even after harvest.
Similarly, managing powdery mildew will protect leaves to maintain photosynthesis and help minimize damage of developing buds. Powdery mildew was observed this week in apple and cherry orchards on young leaves at shoot terminals. Powdery mildew is caused by the fungus Podosphaera leucotricha. As a reminder, sterol inhibitors, strobilurins and succinate dehydrogenase inhibitors control powdery mildew. Captan, Scala, Vangard and EBDC fungicides will not control powdery mildew.
Peach fruit are growing steadily across varieties, and early peach varieties are being harvested (Photo 2). Venture peach fruit were 54 – 58 mm in size at the West Central Michigan Research and Extension Center.
Pear fruit were 44 – 48 mm in diameter for Bartlett pear trees at the West Central Michigan Research and Extension Center. Pear tree shoot growth has been very vigorous this season with extensive new growth for young shoots for varieties like Barlett, Cold Snap and Gem.
Plums are being harvested for early varieties such as golden plums. Early plum fruit ranged from 36 – 40 mm in diameter.
Pest update
Consider scouting reports and block history to target hot spots for orchard pests according to fruitlet stage. Spotted wing drosophila (SWD) was trapped this week in Oceana County at four locations. Japanese beetle is emerging in high numbers from the ground and feeding on leaves of peach, apple and cherry. Pear psylla eggs were observed this week on pear at two locations in the county.
On July 22, the Trevor Nichols Research Center in Fennville, Michigan, trapped pests such as codling moth, redbanded leafroller, oriental fruit moth, San Jose scale and lesser peachtree borer. These pests were also observed in Oceana County as well as dogwood borer this week. At the Trevor Nichols Research Center, apple maggot was also trapped this week at 65.3 apple maggots per trap; however, apple maggot has not been trapped with the Michigan State University traplines in the Grand Rapids, Michigan, region or in the west central region.
Codling moth counts were zero moths per trap on July 22 for three locations across Oceana County. Traps counts are low in some locations in Oceana County this season. Use site specific trap counts to set biofix dates, and consider this Michigan State University Extension article on codling moth management for treatment recommendations and timings.
Dogwood borer was observed this week in Oceana County at an average of 25 per site.
Greater peachtree borer (peachtree borer) has not yet been trapped in the region.
Lesser apple worm was not observed in traps this week.
Lesser peachtree borer was trapped this week with an average of four borers per trap at the West Central Michigan Research and Extension Center.
Rosy apple aphid and woolly apple aphid are common pests in our region. More woolly apple aphids have been observed over the past few weeks.
Obliquebanded leafroller adults were not trapped this week in Oceana County in tart cherry or apple. Some leafroller larvae were observed in apple feeding on leaves.
Oriental fruit moth was trapped at two of three locations in Oceana County with an average of three oriental fruit moths per trap. Management is needed if trap numbers are above the economic threshold (10 adult moths or if fruit injury is found).
For pest and disease management recommendations, please refer to the Michigan Fruit Management Guide (E-154) for product guidelines.
For more information about regional reports, please visit the Michigan State University Extension website.
