Southwest Michigan fruit regional report – April 14, 2015

Last week’s warm rain has greened up turf and plants are moving quickly.

Apricot flower buds at “red tip.” Photo credit: Mark Longstroth, MSU Extension

Apricot flower buds at “red tip.” Photo credit: Mark Longstroth, MSU Extension

Weather

Warm temperatures last week with high temperatures in the 50s and 60s and warm rains moved plants quickly. Low temperatures for the week were all above freezing. Heavy rains on Thursday, April 9, were infection events for early season diseases. This warm rain caused a quick green up of turf and the beginning to bloom for many spring bulbs.

Now is the time to apply dormant treatments to protect crops from overwintering insects and diseases.

Southwest Michigan GDD summary from Jan. 1 to April 12, 2015

Station

GDD 42F

GDD 45F

GDD 50F

Benton Harbor (SWMREC)

140

98

51

Lawton (Lawton)

130

90

47

Fennville (TNRC)

91

60

28

Average for the region

135

94

49

Tree fruit

Growth has jumped over the past week. Heat unit accumulation and fruit development is greater in southern Berrien County than in areas north. Fruit in Berrien County is more advanced than Van Buren County to the north and east. At this stage of development, it would require cold temperatures below 23 degrees Fahrenheit to cause significant damage tree fruit flower buds. See “Freeze damage depends on tree fruit stage of development” from Michigan State University Extension for more information.

Apricots are at red tip. More tender varieties are showing few viable flower buds, but crop potential is generally decent so far. Normal apricot bloom in southwest Michigan is about April 15, but it is likely we will be at least a week late.

Peaches are at swollen bud to green calyx. Winter-damaged fruit buds are dropping from trees. Some growers report significant losses and others report they still have more than enough flowers for a good crop.

Sweet cherries and tart cherries are at first green to green tip and show little obvious winter injury. Later as buds swell and burst, damage to the pistil will become more apparent. Some sweet cherries may be too advanced for copper materials for bacterial canker. Sweet cherries are sensitive to copper, so avoid spraying copper when green tissue is exposed. Tart cherries are very tolerant to copper and copper can be used throughout the season. Copper applications may be helpful in reducing bacterial canker in cherries.

Japanese plums are at green tip and European plums are at first green. Winter injury to apriums and plumcots is becoming more obvious as branch dieback and trunk gumming. Some varieties are showing significant cankering due to bacterial canker.

Some winter injury is expected in Japanese plums, which are less cold hardy than European plums. Little, if any, damage is expected in European plums, which are more winter hardy.

Apples of the early blooming varieties such as Zestar are at 0.5-inch green to early tight cluster in Berrien County, but most varieties are at 0.25- to 0.5-inch green. Tree development is ahead of where the growing degree day table in E-154 indicates we should be.

April 9 was a significant scab infection episode. Scab ascospore trap catches are higher than last year. We will soon leave the window for copper applications for scab control and fire blight management. We do not expect any winter injury in apples in 2015.

Pears are at bud burst. Pear psylla are flying.

Small fruit

Grapes have not yet begun growth. Winter injury to wine grapes varies between varieties and different vineyard sites. Initial assessments early in the winter indicated damage from the cold in January and growers have been warned to delay pruning until after they can carefully assess winter injury. Growers should also examine the trunks of vines as damage to the cambium just above the snow line has been found in many vineyards.

Blueberry flower buds are swollen and beginning to burst. As the plants green up, winter injury will be easier to assess. Leaf buds are just beginning to show green tip on the most advanced buds. Green leaf tissue is susceptible to mummy berry shoot infections. Warm, wet weather should have brought out mummy berry trumpets and growers should scout their fields for mummy berry infection to assess their risk.

In strawberries, new leaves are emerging from the crown. In southern sites, the flower truss is visible in the crown. Over-wintering mulches should be removed and raked between the rows.

Brambles are at green tip. Now is the time for lime sulfur treatments for anthracnose to be applied.

Upcoming meetings

Our next Monday fruit IPM meeting is April 20 at Fruit Acres Farms, 3452 Friday Rd., Coloma, MI 49038, at 5 p.m. Two Michigan pesticide applicator recertification credits will be given for these meetings.

The Van Buren County Blueberry Pre-bloom meeting is tentatively scheduled for Thursday, April 23 at Haven Harvesters in South Haven, Michigan. Look for more information soon in upcoming regional reports.

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