East Michigan fruit regional report – June 7, 2016

Farmers received much-needed rain, but most of the region has had dry soils for the last three weeks. Apple growers saw fruit drop over the past week.

Weather

Most growers had only a touch of rain over the weekend, but a few fortunate growers had just over an inch of precipitation from the widely scattered thunderstorms that moved over the region. Most of our region has had little to no rain over the past three weeks.

Our soils are generally very dry, and growers are working hard to keep fruit crops watered, especially on newly planted tree and small fruits. Strawberry growers may see reduced berry size for the second and later harvests as a result of dry soils.

Our season has jumped ahead of normal in terms of fruit crop growth stages and degree-day totals; we are about three days ahead of normal.

East Michigan growing degree day totals for March 1 to June 6, 2016

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

946

767

523

Deerfield (Monroe County)

1112

908

619

Emmett (St Clair County)

901

734

505

Flint (Genesee County)

1036

853

599

Freeland (Saginaw County)

902

741

516

Lapeer (Lapeer County)

954

785

552

Pigeon (Huron County)

785

638

440

Romeo (Macomb County)

971

792

548

Tree fruits

Apples are mostly 22 to 26 millimeters for growers in the south and 17 to 20 millimeters for growers along the I-69 corridor, with the exception of growers close to Lakes Erie or Huron, where fruit growth is delayed. A fair amount of fruit drop has occurred over the past week. Apple fruitlets that appear to be set continue to size well. Most blocks appear to have thinned well, and some have dropped too much fruit and thus may have a lighter than normal crop. It is still too early to get an accurate sense of crop load.

The two new insect pests to report this week in apples are obliquebanded leafroller adult trap catch and woolly apple aphid adults being seen on tree trunks. European red mite adults have jumped to threshold levels in a few apple blocks in the past week. Codling moth trap catch continues to be very high in some blocks, especially in non-pheromone disrupted blocks. Tarnished plant bugs continue being seen in all tree fruits. Plum curculio egglaying scars are more common in a few apple blocks this week. Beneficials continue being found in greater numbers; new this week is Zetzellia “yellow” mites.

New diseases to report this week are apple scab lesions on leaves showing up in many apple blocks and fire blight strikes are being found at just a few orchards. We had three apple scab wetting events at my apple scab spore trapping location over the weekend. I caught spores in the first two wetting events, but the third wetting event was a quick burst of light rain, and the rain was so light that it may not have triggered spore release. The number of spores being caught is declining with each rain or wetting event (14 spores in the June 4 rain and nine spores in the June 5 rain). So, are we done with primary apple scab season? It is hard to tell for sure, as I need another rain event to call an end to primary apple scab for the season. Stay tuned for details!

Fire blight shoot strikes started to be found, mostly from flower cluster infections, over the weekend at just a few farms. These are generally farms where fire blight was an issue last season. Growers need to do a thorough job of scouting this week for fire blight shoot strikes. Powdery mildew continues to be found in more apple blocks. Many terminals are completely infected now.

Pears are mostly 17 to 20 millimeters in diameter. Pear scab leaf symptoms started to show over the weekend at a few farms. The pear crop is variable in most blocks this season. Pear psylla adults continue to fly with all stages present.

Peaches are just over an inch in diameter for most growers. Many farms have started hand-thinning. Oriental fruit moth trap catch continues to be seen at many farms, with most conventional blocks well-beyond biofix. I have not seen any terminal flagging from oriental fruit moth feeding, but it is expected soon as southwest Michigan reported seeing it. Tarnished plant bugs continue being seen in all tree fruits. Peach leaf curl symptoms are being seen in many peach blocks this season, more than I have ever seen in any season.

Sweet cherries are 12 to 16 millimeters in diameter for the largest fruit. They are continuing turning straw-colored and early varieties are starting to turn red. We may be harvesting strawberries and sweet cherries at the same time this season. I am seeing a good crop of sweet cherries the past few weeks. Some of the smaller fruit continues to turn a light tan color and may drop soon. Brown rot control sprays continue being made. Tarnished plant bugs continue being seen in all tree fruits.

Tart cherries are mostly 11 to 14 millimeters in diameter. Tart cherry crop load is more variable this season and appears to be a shrinking crop. Leaf yellowing and drop is being seen in many blocks of tart cherries, caused by bacterial canker.

Plums are 18 to 19 millimeters in diameter for European types, and Japanese types are approaching 1 inch in diameter. The crop load is variable in both types, especially in some Japanese varieties as they have little to no crop.

Small fruits

Grapes continue putting on good growth the past few weeks; Concord canes have 30 inches of new growth and European varieties have 24 inches of new shoot growth. Flower buds have elongating for both types and are ready to bloom in the next few days. Rose chafer adults are starting be found in a few vineyards.

Strawberry harvest is just starting in the last few days for farms in the southern parts of our region, and farms further north will open this coming weekend. We may be harvesting strawberries and sweet cherries at the same time this season. It was amazing to see how quickly berries have ripened in the past 10 days.

I am concerned about berry size at many farms, especially for the second and subsequent pickings where not enough irrigation was applied the week after bloom when berry cell division was occurring. These farms may have decent berry size for the first picking, but then it will decline rapidly.

Fields look spectacular at a few farms, but at other farms the berry plants look weak and off-colored. Michigan State University Extension recommends light nitrogen applications of urea at many farms this season to overcome this lack of new growth.

Raspberry shoots, leaves and flowers continue emerging for summer fruiting types, with 16 inches of new shoot growth. Flower buds continue expanding on summer raspberries. New canes continue emerging from the ground in fall raspberries; the longest canes are 16 to 20 inches in length.

Blueberries are 8 to 11 millimeters in diameter. Blueberry stem gall wasps continue emerging from overwintering galls and are looking lay eggs on new shoots. As soon as bees are out of the planting, control sprays should be made for this pest. 

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