West central Michigan tree fruit update – June 25, 2024
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EmailSweet cherry harvest has begun for early varieties. Tart cherry growers are preparing for harvest as early as next week.
Weather update
Over the past week, high heat and humidity have continued with highs in the 70s to upper 80s and lows in the 60s, according to the Hart Enviroweather station. Temperatures will be slightly cooler this week with highs in the 70s and lows in the 50s and low 60s.
Over the past few days, weather conditions have been mixed with rainy and dry days with heavy rains over the weekend. On June 22 and 23, almost 2 inches of rain fell at the Hart Enviroweather station. Severe storms swept across the region overnight on June 24 and 25. Rain, high winds and hail have been reported. Relative humidity ranged in the 70s and 80s this week, and evapotranspiration has been high. More rain is forecasted for Friday, June 28.
Fruitlets are growing steadily (Photo 1), and crop load looks good across fruit crops in the region. Based on the Hart Enviroweather station for June 24, current growing degree-day accumulation is 1,477 GDD42 and 847 GDD50.
Soils are saturated with soil moisture ranging from 22 – 24% at 4 inches deep in the soil profile and about 11% at 20 inches soil depth on June 22 – 24 for the Hart Enviroweather station. Higher moisture levels are expected after the storm this morning on June 25. Water has steadily infiltrated into the soil profile and is readily available for fine roots, which are produced in the top 1.5 – 2 feet of soil. These roots are responsible for taking up water and nutrients. This water availability is critical to support rapidly growing fruitlets and shoots this time of year.
With the consistent and heavy rains this season, fertilizer applications may not be available to trees at this time and may have moved past the root zone. Consider soil test results and nutrient needs for this season based on sap analysis or leaf tissue analysis over the next few weeks to determine if another application of fertilizer (particularly nitrogen) may be needed. With moist soil conditions and continued chances of rain in the forecast, more frequent applications of fertilizer are recommended in smaller rates compared to one or two applications in larger rates during the growing season.
Soil temperatures at a depth of 2 inches have ranged from the high 70s into the 80s. High soil temperatures can inhibit root activity and cause stress. Soil temperatures at 4 inches deep have been in the 70s and low 80s over the past week. Deeper in the soil profile, temperatures fluctuate less and have ranged from the low to mid 60s although soil temperatures have increased slightly to the low 70s on days when solar radiation is high at 8 and 20 inches deep.
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
For early apple varieties, most advanced fruitlets range from 50 – 55 millimeters (mm) for Zestar, and Honeycrisp fruitlets ranged from 44 – 47 mm. Jonagold were 42 – 46 mm, and Minnieska fruitlets were 48 – 52 mm in Hart.
With recent storms bringing high winds and hail, trauma may have occurred in some orchards. Copper products help minimize infection and spread of the fire blight bacteria. Protective sprays after trauma should be applied within 4 – 12 hours after the trauma event.
Tart and sweet cherry are growing rapidly (Photo 2). Fruit size for early sweet cherry varieties are 28 – 30 mm. Early sweet cherry varieties are being harvested such as black pearl and ebony pearl. Red color development and flavor has been excellent. Due to heavy rains over the weekend, scout for potential fruit cracking in sweet cherry blocks due to water resting on the fruit surface or water uptake through the roots. Tart cherry fruitlets are about 20 – 22 mm in size and are turning red. Fruit is also beginning to soften.
Consider harvest time and appropriate timing for ethephon applications for sweet and tart cherry orchards. Ethephon is a plant growth regulator that helps loosen fruit to enhance detachment of cherries during mechanical shaking by dissolving the abscission layer between the pedicel and fruit. More information on ethephon and application recommendations can be found here: Ethephon on cherries - MSU Extension.
Cherry leaf spot pressure has been high with warm and wet weather conditions. Lesions on leaves, stems and fruit have been observed across the region. Continue protecting leaves from rapid cherry leaf spot infection. As a reminder, chlorothalonil, copper products and Captan are effective materials against cherry leaf spot. Note that chlorothalonil has a 10-day retreatment interval, and application of Captan or copper products may be needed sooner than 10 days to protect leaf and fruit tissue. Note that Captan and copper application at high temperatures (80s) may lead to phytotoxicity. Apply these products at cooler temperatures or at nighttime.
Powdery mildew has been observed in apple and cherry orchards in the region. 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.
American brown rot was observed this week in a mature sweet cherry block. Cracking from rain or wounding due to bird damage or bacterial canker infection in sweet cherries leads to higher likelihood of brown rot infection. As fruit gets closer to harvest, susceptibility to brown rot increases. Consider if brown rot management is needed. Using Indar may not be effective, even at the highest labeled rate of 12 ounces per acre. Previous research and resistance screening of American brown rot isolates in west central and northwest regions found that most screened fungal isolates had functional resistance to Indar. Find more information about this study. Effective materials for managing American brown rot include Merivon, Miravis and Cevya. Full coverage of all rows will be important to manage this disease.
Peach fruitlets are growing steadily with many fruit setting this year across varieties. Venture peach fruitlets are 38 – 42 mm in size at the West Central Michigan Research and Extension Center. Some growers are hand thinning peaches this week in the region.
Pear fruitlets are growing rapidly and fruit set is moderate for varieties such as Bartlett, Gem and Cold Snap. The largest fruitlets were 32 – 36 mm in diameter for Bartlett pear trees at West Central Michigan Research and Extension Center.
Plums are growing rapidly with high fruit set for many varieties. Average fruitlet diameter for Stanley plum was 25 – 30 mm.
Pest update
Consider scouting reports and block history to target hot spots for orchard pests according to fruitlet stage. Spotted wing drosophila was trapped this week in Oceana County at four locations. Spotted wing drosophila has been observed in other fruit grower regions across the state.
On June 24, the Trevor Nichols Research Center in Fennville, Michigan, trapped pests such as codling moth, oriental fruit moth, adult obliquebanded leafroller and greater peachtree borer. Dogwood borer was trapped at the Trevor Nichols Research Center and two locations in Oceana County this week.
Codling moth counts were two moths per trap on June 24. This is first generation flight of codling moth. If moths are above economic thresholds, consider treating if mating disruption has not been used. The first generation biofix date for Oceana County was set for June 1 according to trap counts at the West Central Michigan Research and Extension Center. Other sites in Oceana and Mason counties had higher traps counts and earlier biofix dates, so trapping by orchard block or in high population areas in the orchard is critical. According to the Hart Enviroweather station, second generation adult emergence will not be for another few weeks.
Dogwood borer was observed this week in Oceana County. Adult emergence is typically in mid-June, and egglaying occurs over a four- to six-week period. Trees with burr knots (adventitious roots) are highly susceptible to dogwood borer infestation. Burr knots typically develop on the above ground portion of the clonal rootstocks. Dogwood borer larvae feed inside the burr knots, and if larvae continue to feed below the bark, damage can eventually girdle the tree. For more information, read this article about the borer pest complex and control alternatives by John Wise and Julianna Wilson, Michigan State University Department of Entomology.
Greater peachtree borer (peachtree borer) has not yet been trapped in the region, but is expected soon as surrounding regions are trapping these borers.
Green apple aphid nymphs and adults were observed feeding on the underside of leaves this week. Scout to determine if management is needed. Many aphid predators such as lady beetles and lacewings can help keep aphid populations in check. In general, established orchards can sustain thresholds of an average of three to four infested leaves on terminals before fruit damage occurs from honeydew.
Green peach aphid was observed this week. Adults and nymphs were present and caused leaf curling and yellowing from feeding on the undersides of leaves. Monitor orchard blocks to determine if a treatment is needed.
Lesser apple worm was observed in low numbers this week. Only 0.5 adults per trap were found in Oceana County. Lesser apple worm larvae feed on small fruit or can borer into succulent shoot terminal this time of year. Apply sprays that target adults before egg lay occurs.
Lesser peachtree borer has been observed in the region. An average of 1.3 borers per trap were counted at the West Central Michigan Research and Extension Center. Similar to greater peachtree borer, mating disruption is recommended for lesser peachtree borer in orchard blocks with at least 5 acres and trees that are at least 3 years old.
Rosy apple aphid and woolly apple aphid are common pests in our region. Scout for colonies of rosy apple aphid nymphs in fruit clusters. Woolly apple aphids were found in pruning scars and nodes of interior and upper branches. They are starting to become more prevalent in orchards and are often denser in the center of the orchard compared to the orchard edge.
Obliquebanded leafroller adults were trapped this week in Oceana County in tart cherry and apple orchards. An average of three adults per trap were found in apple.
Oriental fruit moth was trapped at two locations in Oceana County with an average of 4.5 oriental fruit moths per trap. This may be the start of the second generation for some locations. Scout for oriental fruit moth evidence in peaches by looking at flagged shoots where first generation larvae burrowed into shoot terminals.
Spotted wing drosophila is now present in Oceana County. As the fruit are turning red and softening, they are susceptible to SWD infestation. More information and management recommendations can be found in this updated article with trapping information and updated management recommendations.
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.
