East Michigan fruit update – May 28, 2019

Robert Tritten, Michigan State University Extension - May 28, 2019

Bloom has ended for tree fruits in the past week and strawberries are finally in full bloom. Apple thinning is the challenge for the week and fire blight risk remains high.

Saskatoons are at fruit set. Photo by Bob Tritten, MSU Extension.

Weather

With a week of much warmer and more normal temperatures, growth in all our fruit crops has finally taken off. We also saw big additions to our growing degree day (GDD) totals for the week with the warmer temperatures, and many of our Michigan State University Enviroweather stations across the region added nearly 100 GDDs base 50 in the last week alone. However, our season is still running just over a week behind normal when looking at flowering stages and GDD totals for region.

Last Tuesday morning, May 21, we had several farms that saw low temperatures dip close to freezing. Some orchard frost fans turned on and strawberry growers needed to frost protect. Little to no ice formed in strawberry fields that were being frost protected. I have not seen any damage to fruit crops due to this cold event.

Most areas of east Michigan have received another inch of precipitation over the last week. Many for our MSU Enviroweather stations across the region received measurable precipitation in four to six of the last seven days.

Our soil moisture conditions have generally gone back to being wet. Most tree fruit blocks have been badly rutted this spring due to spraying operations that were done when our soils were so wet. While most fruit growers have finally finished planting, there are still a few trees and small fruit plants that need to be planted yet this spring. This has been one of the latest years growers can remember to get fruit crops planting.

With the extensive rains of this spring, weed growth has been lush. Further, many preemergent herbicides have been washed to deeply into the soil profile to be effective any longer.

East Michigan GDD totals for March 1 to May 27, 2019
Location	GDD42	GDD45	GDD50
Commerce (Oakland County)	559	428	256
Deerfield (Monroe County)	674	522	324
Emmett (St Clair County)	429	317	174
Flint (Genesee County)	619	482	300
Freeland (Saginaw County)	527	406	243
Lapeer (Lapeer County)	554	427	262
Pigeon (Huron County)	425	316	178
Romeo (Macomb County)	568	435	260

Tree fruits

Apple growth has been rapid over the past week, with many new leaves developing and a good amount of new lateral growth on branch tips. Apples in the mid-parts of our region (Ann Arbor through Flint) are mostly at 4 to 6 millimeters, with early apples being closer to 12 millimeters.

Most apple varieties have good fruit set on them. Over the entire region, there are three varieties that have short crop: Honeycrisp, Crispin or Mutsu and Northern Spy, and some Golden Delicious and Golden strains. This is not true for all blocks, but a generalization across the region.

Insect pest pressure has picked up again this week for the second week in a row. New apple pests to report this week include catching the first plum curculio of the season. Also, I had a report yesterday, May 27, of one grower catching four codling moths in traps. Last week we saw the first catch of San Jose scale males in traps, a few green apple aphids and a few potato leafhopper adults. More farms are seeing low numbers of oriental fruit moth adults being caught in traps in apples and other tree fruits. Also, a few obliquebanded leafroller larvae continue to be found in apple terminals at most farms. Redbanded leafroller and spotted tentiform leafminer trap catch has dropped back again this week for both.

More growers are finding a few apple scab lesions on some of the first of the season leaves. They were first seen on leaves on May 17 and 18. Apple scab spore release continued in wetting events this past week and from rains over night at my trapping location. Trap catch numbers are declining rapidly. Many growers are asking if we are at the end of primary apple season yet? The only thing I can say for certain is that at my trapping location, we are not at the end of primary apple season as of this morning. However, I suspect that with all the wetting events the two southern most tiers of counties have had this spring, we are either done or very close to being done with primary apple scab season. However, there is no way to tell for certain. Many apple growers have had three to four apple scab wetting events in the past week, with most growers having one to two infection periods. This has been a tough apple scab season.

The Enviroweather fire blight model EIP numbers were close to or over 100 for most growers over the weekend and are high for the next few days. So, keep an eye out for an infection event. Most apple growers have applied three to four streptomycin sprays this season. There is still ragtag bloom that needs to be protected in most apple blocks.

I believe I saw my first powdery mildew-infected branch tip of the season yesterday morning in my visits to apple growers. I will need another week to confirm this finding.

Pears are 7 to 13 millimeters in size. Pear psylla adult flight continues.

peach-leaf-curl-tritten — Symptoms of peach leaf curl on peaches. Photo by Bob Tritten, MSU Extension.

Peaches are mostly at early shuck split. Late last Wednesday, the first signs of peach leaf curl started to show up. In a few blocks, the infestation is severe. Since then, many growers have reported seeing signs of this disease. At this time of the season, there is no control.

Sweet cherries are 10 to 13 millimeters for the largest fruits. Most growers have a good crop of sweets coming along.

Tart cherries are 6 to 8 millimeters for the largest fruits.

Plums are at shuck split for European varieties and Japanese varieties are at fruit set. Many Japanese varieties have seen excessive fruit drop in the past week.

Small fruits

Strawberries are in full bloom at most farms across the region. There are a few thimble-sized berries at the ends of rows in a few early varieties. Leaf growth has continued to improve. A few growers needed to frost protect last Tuesday morning. It will be a late harvest start this season. I am planning at least one preharvest strawberry meeting this season, look for an announcement on the MSU Extension Fruit & Nuts page later this week.

Yesterday, I saw just a few flower petals that were fed on by strawberry clipper before the flower was open. The sightings were just a few and damage was light. Do a good job of scouting in the next few days for this pest. Most growers have not been able to apply all of the cover sprays this season for gray mold control due to wet soils.

Raspberry canes continue to emerge from the soil for both summer and fall raspberries. Most summer raspberries have newly emerging canes that are 15 to 20 inches in length and fall raspberries have the longest canes approaching 10 inches in length. Summer raspberries have flower buds emerging from the tips branched canes, but none are open yet. A few fall bearing blackberry growers have shared that they are not seeing any new canes emerging from the soil. Some of this might be due to winter injury.

Blueberries are at full bloom for Jersey. Some tips of more vigorous late summer growth canes are drying up due to winter injury.

Saskatoons are at fruit set to the largest size fruit being 4 to 6 millimeters.

Grapes are at early shoot growth; most have 6 inches of new growth.

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