MSU Extension

Weather report

The weather continues to be warm and dry across northwest Michigan. Daytime temperatures are in the 80s, and overnight temperatures dip into the mid-50s. Days have been very sunny and pleasant. The region really needs rain to size the cherry crop. We did receive some rainfall last week, June 29-30, but the amounts varied at the different Michigan State University Enviro-weather stations. The Northwest Michigan Horticulture Research Center received 0.66 inch of rain, the Elk Rapids Enviro-weather station recorded 0.37 inch, East Leland recorded 0.41 inch, Northport recorded 0.3 inch and Kewadin recorded 0.27 inch. Higher amounts of rainfall were recorded at Eastport with 0.84 inch and Old Mission with 0.72 inch. Very little rainfall fell in Benzonia and Bear Lake: 0.18 inch were recorded at both Enviro-weather stations.

Crop report

Sweet and tart cherries are ripening, and the crop seems to be coming on quickly with the recent heat. Many growers have ethephon on their sweet cherries, and some growers will start shaking sweets this weekend. We are harvesting earlier sweet cherry varieties at the research center. Some fresh market growers have started hand-harvesting sweet cherries. Tart cherries are moving along, and the crop is looking more uniform in ripening this week compared to last week. Tart cherry harvest is underway in southwest Michigan, and growers in west central Michigan anticipate starting harvest this week. We will likely face some challenges to have a timely harvest of this large crop.

2016 growth stages as of July 4, 2016

• Bartlett pear – 29 millimeter fruit
• Potomac pear – 34 millimeter fruit
• Mac – 30 millimeter fruit
• Gala – 36 millimeter fruit
• Red Delicious – 40 millimeter fruit
• HoneyCrisp – 39 millimeter fruit
• Montmorency – 19 millimeter fruit
• Balaton – 19 millimeter fruit
• Hedlfingen – 22 millimeter fruit
• Gold – 19 millimeter fruit
• Napolean – 18 millimeter fruit
• Riesling – buckshot berry

Pest report

In the last week, more spotted wing drosophila (SWD) traps caught SWD, and in some areas trap numbers indicate this population is on the rise. Anecdotally, orchards that were infested with SWD last season seem to have higher trap numbers this season compared to orchards that had low or no SWD incidence. We will continue to monitor this trend and the possible implications for higher, localized SWD populations next season. The latest SWD catch numbers in our region are available in the table below.

MSU Extension reminds growers that if SWD has been found on their farm or in a neighboring farm and cherries are susceptible (i.e., at or past straw-colored), SWD management programs should be underway. Last week, tart cherries in more northerly areas were still fairly green, but these fruit will be susceptible to SWD egglaying as soon as the fruit begin to ripen, which will likely happen soon.

Most growers have been actively managing for SWD at this time; we encourage growers to pay particular attention to insecticide label language for target pests, number of applications, pre-harvest intervals, retreatment intervals, etc.

Total SWD catches per region:

• Centerville Township - 5
• South of Suttons Bay - 3
• Old Mission - 10
• M-72 west corridor - 9
• Elk Lake Road – 4
• North of Suttons Bay – 1
• Eastport - 1
• Northport-Omena - 3
• Benzie – 2
• Yuba – 1
• Bingham – 3
• East Leland – 2

Cherry fruit fly activity has been reported in the Acme and East Leland, Michigan, areas, but trap numbers of this pest have been low or off to a slow start. Conditions have been dry and the next wetting event could result in a high cherry fruit fly emergence. For early detection, we encourage scouts and consultants to continue monitoring for this pest, particularly after the next rain. We have not found cherry fruit flies at the research center. As mentioned in previous reports, we ask local scouts and consultants to please call the research center at 231-946-1510 with any cherry fruit fly captures and locations.

Obliquebanded leafroller trap numbers were down this week in cherries at the research center and egg hatch is ongoing. The research center’s biofix (i.e., first date of sustained catch) for this pest was June 17. According to Enviro-weather, the research center has accumulated 502 growing degree-days (GDD) base 42, and peak egg hatch occurs around 450 GDD base 42 after biofix. Where obliquebanded leafroller trap numbers have been high and around 450 GDD base 42 after biofix have been accumulated, some growers are using or planning to include an efficacious material for obliquebanded leafrollers. As a reminder, Delegate is effective for obliquebanded leafrollers and SWD; however, a material for cherry fruit flies should be included as Delegate is not as efficacious against this pest. Obliquebanded leafroller resistance to the organophosphate class of insecticides and cross-resistance to the pyrethroids has been documented in Michigan and growers should not rely on these material classes to provide adequate obliquebanded leafroller control.

Overall disease incidence in cherries and apples remains low. Fire blight has slowed drastically in the last week and dry weather has helped to dry up ooze. If the region receives stormy weather, trauma blight could be a concern.

We found very little activity in the research center’s apples this week. No codling moth, oriental fruit moth or obliquebanded leafroller adults were detected in the research center’s traps.