East Michigan fruit update – April 17, 2018

The grip of late winter weather just won’t let go, continuing to hold back fruit crop development.

Weather

The much-below-normal temperatures have held back fruit development over the last week, almost to a standstill. Six of the eight Michigan State University Enviroweather stations that I list in the table below still have degree-day base 50 totals in single digits. Growers near Deerfield, Michigan, and south of the I-94 corridor have recorded almost twice the degree-days as growers to the north. However, even there, this spring is one of the latest growers have ever seen.

Our season is at least three weeks behind normal. That being said, if we get above-average temperatures late spring, we can catch up to more normal in a relatively short timeframe. Based on the short- and long-term weather forecast predictions, I predict we will have a very short spring this season.

A few peach, sweet cherry and blueberry varieties are showing signs of some slight bud swelling, but most fruit crops are still not showing signs of spring growth. Most of our region continues to have soils that are too wet to do any fieldwork, other than pruning activities in tree fruits, blueberries and grapes. I have not heard of any tree plantings.

It is still too early to determine the full extent of flower bud damage from winter cold temperatures in peaches and sweet cherries; this is mainly in orchards north of I-94. The coldest days of winter for most of our Enviroweather stations were recorded the mornings of Jan. 6 and 7, and for others the coldest morning was Dec. 28. Low temperatures ranged from -8 to -15 degrees Fahrenheit for the reporting stations on the list in the following table.

I continue to hear reports from fruit growers that their lowest recorded temperature this winter was -20 F. The weather last fall was relatively mild to the time between Christmas and New Year’s when we had a sudden drop in temperatures. Most of the damage to these stone fruit crops occurred at this time. It almost appears that the flower buds were freeze-dried. These damaged flower buds have been slowly dropping throughout the winter.

East Michigan GDD totals for March 1 to April 16, 2018

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

28

18

13

Deerfield (Monroe County)

51

34

18

Emmett (St Clair County)

28

13

 9

Flint (Genesee County)

31

19

 8

Freeland (Saginaw County)

24

14

 6

Lapeer (Lapeer County)

25

16

 8

Pigeon (Huron County)

10

 5

 2

Romeo (Macomb County)

29

18

 9

Tree fruits

Apples are mostly dormant, but a few early varieties are at very early silver tip. Most growers found a nice crop of flower buds when trees were being pruned this winter. Growers are pruning through this cold April.

I have set up my apple scab trapping equipment for the season and am catching a few spores with each wetting event. Many Enviroweather stations have recorded an apple scab infection period due to the very long wetting periods. It is unusual to see infection periods with temperatures being so cold, however there is no green tissue yet in apples, so these apple scab infection periods can be ignored.

Many growers are seeing higher populations of overwintering San Jose scale as they have pruned this winter. Dormant oil applications are being planned by many growers to help start the process of controlling these scale populations.

Pears are mostly dormant. Even though cold weather has continued, I am seeing a few pear psylla adults.

Peaches are showing some signs of flower bud scales cracking in a few early varieties. Most varieties are at bud swell. Hold off the beginning of pruning until flower buds become more visible to determine any possible crop loss from cold this winter. As was discussed in the weather section of this report, there has been some flower bud damage this winter.

Sweet cherries are at bud scale cracking on a few varieties, most are at swollen bud. As was discussed in the weather section of this report, there has been some flower bud damage in sweet cherries this winter.

Tart cherries are dormant to early bud swell.

Plums are still dormant for European types and at bud swell for Japanese varieties.

Small fruits

Grapes are dormant and pruning continues.

Strawberry leaves continue to very slowly emerge from the crown. Most strawberries are still covered with straw mulch. Straw removal may begin later this week when soils dry out to allow fieldwork.

Raspberries remain dormant. Most fall raspberries have been mowed off.

Blueberries are mostly dormant with a few varieties at bud swell. Pruning continues.

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