MSU Extension

Weather report

Daytime temperatures around the Fourth of July were warm and dry, and we hit the low 80s for a three-day stretch. Conditions were also dry, and visitors to the National Cherry Festival had perfect weather for our big annual event. Temperatures cooled down a bit over the weekend, and we had overcast conditions on July 9, which turned into rain by evening.

The rainfall totals for Sunday evening were variable across the region, but most Michigan State University Enviroweather stations recorded 0.25-0.4 inch of rainfall. The rainfall was consistent, fell gently, and was not accompanied by high winds or other damaging conditions.

The region has had more rain this season than in many years, and we have accumulated almost 11 inches of rain since March 1 at the Northwest Michigan Horticulture Research Center. Unlike most years, our grass is still green into July.

The rainfall has also really impacted fruit trees where growth has been excellent, and trees are lush except for blocks where leaf spot is showing up in tart and sweet cherry blocks. We have accumulated 1,598 growing degree-days (GDD) base 42 and 950 GDD base 50.

2017 growth stages as of July 11, 2017

• Bartlett Pear – 28 millimeter fruit
• Potomac Pear – 37 millimeter fruit
• McIntosh – 50 millimeter fruit
• Gala – 40 millimeter fruit
• Red Delicious – 45 millimeter fruit
• HoneyCrisp – 42 millimeter fruit
• Montmorency – 19 millimeter fruit
• Balaton – 22 millimeter fruit
• Hedelfingen – 22 millimeter fruit
• Gold – 22 millimeter fruit
• Napoleon – 24 millimeter fruit
• Riesling – Buck shot berries

Crop report

Hand-harvested sweet cherries started coming off last week, and machine harvest will be in full swing in many areas of the region by the end of this week. Growers put on ethephon last week in anticipation of sweet cherry harvest beginning in earnest this week and into next week. Most varieties of sweet cherries are 22 millimeters in size, and many are starting to eat well. We tested brix on sweet cherry varieties this morning: Regina at 16 and Emperor Francis at 16.5.

Growers are likely going to move quickly through sweet cherries to minimize the impacts of the wet conditions and potential for American brown rot. Additionally, tart cherries are ripening quickly, and growers will need to move through sweets to start on the tart cherry crop. The tart cherry crop is variable, but there are orchards with big crop loads and will take some time to move through these blocks. Tart cherry size is very good in many blocks—fruit is plump likely due to the rain. Despite all the rainfall we have had this season, we have less cracking than anticipated. We were pleasantly surprised Sunday’s rainfall did not result in substantially more cracking. Cracked fruit are present, but there is far less than expected given the season.

The apple crop is also looking good. The rain has certainly improved fruit size, and apple trees have significant growth on them in most blocks. 

Shoot growth has continued at a fast pace in grapes. Protecting clusters from powdery mildew is still the chief concern. Rose chafers have finally vanished, but Japanese beetle adults have been seen in the Traverse City, Michigan, area during the past week.

The saskatoon crop is close to 75 percent ripe at some sites and harvest is well-underway. There have been no verified infestations of spotted wing Drosophila so far.

Pest report

As mentioned previously, sweet cherry harvest is ramping up and tart cherry orchards have ripened quickly in the last week. Overlapping harvest of sweet and tart cherry orchards will be challenging for balancing harvest timing with pre-harvest pest/disease management programs.

Spotted wing drosophila (SWD) management has continued to be at the forefront of growers’ minds. We detected SWD flies at the earliest time during the season that they have been found in our region. As host fruits have ripened, we have observed increases in trap numbers and higher pest pressure in orchards this season. SWD larvae have been detected in low levels in fruit collected from commercial orchards; Michigan State Univeristy Extension advises continuing with the best possible SWD management programs. Please see the article, "Managing spotted wing Drosophila in cherries at harvest time," for helpful information on SWD management.

Obliquebanded leafroller flight is ongoing and trap numbers have been consistent over the last two weeks at the center. According to degree-day accumulation, obliebanded leafroller eggs hatched late last week and is ongoing at this time. We observed a small obliquebanded leafroller larva in our trap line at the center this morning.

As harvest approaches, remember that due to resistance concerns, organophosphate insecticides are not suggested as a primary tool to control this pest. Furthermore, due to cross-resistance the pyrethroid insecticide class is also not recommended for obliquebanded leafroller. These two insecticide classes have been widely used for SWD management and growers will need to include a different material to target obliquebanded leafroller in blocks where obliquebanded leafroller is a concern. If you use Delegate for obliquebanded leafroller, include an insecticide rated excellent for SWD. The product Exirel is rated excellent for obliquebanded leafroller, SWD, and cherry fruit fly. No cherry fruit flies have been detected at the center, but we have had reports of cherry fruit fly detections in other blocks.

As mentioned in last week’s report, cherry leaf spot is evident in orchards with most areas having a low to moderate infection; some isolated orchards have high disease incidence. With the current level of infection, many orchards will likely defoliate early this season.

Although the region has been fortunate with less cracking than we would have expected with the season’s wet weather, American brown rot is evident in orchards. Some isolated orchards have a high level of brown rot incidence that appears to have developed on what we would typically call ‘June drop’ fruit that did not drop from the trees.

Apple maggot traps were deployed at the center last week and we caught the first apple maggot this week. Codling moth trap catches continue to be low in our trapline.

July “First Friday” Grape Meeting

The next First Friday Grape Meeting will be July 14 (the second Friday in July, in order to avoid the Cherry Festival) at Ten Hands Vineyard on Old Mission Peninsula, located on Mission Road just south of the Old Mission General Store.

The topic of this meeting is “Foliar Fertilization Programs in the Vineyard” and will be led by Craig Cunningham of Cunningham Viticulture Services. Cunningham has utilized foliar programs in vineyards for more than 10 years, including Ten Hands Vineyard, owned by Tom Petzold.

We will also walk the vineyard for informal scouting, discussing issues as they come up. Tom will answer questions on his vineyard practices (composting, compost tea use, growing grass under the vines, etc.) to round out the session.