SW Michigan Fruit Update

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Southwest Michigan, June 2, 2008

Mark Longstroth, Bill Shane

Weather

Last week’s temperatures were warmer with highs in the 60s and 70s and lows near 40.  There were scattered frosts on Wednesday and Thursday mornings that caused little damage.  Friday was windy and cloudy and offered a little rain.  Rainfall totals varied from a trace to a third of an inch.  This was a disease infection period for some areas, depending on where the rains fell.  Soils are really drying out and shallow rooted berry crops will benefit from irrigation.  The weekend was warm.  Temperatures will be cooler for the next couple of days near 70’s, with a good chance of rain.  We expect hot temperatures at the end of the week with highs in the upper 80’s. Our GDD totals still lagging ten days behind normal. 

Southwest Michigan Growing Degree Day Totals March 1 through June 1, 2008				Grapes, from April 1
Location	GDD 42	GDD 45	GDD 50	GDD 50
Berrien Springs:	806	647	430	420
Scottdale:	792	634	417	409
SWMREC:	729	581	379	373
Bainbridge:	750	602	400	393
Hartford:	713	570	375	371
Lawton:	814	658	439	434
Grand Junction:	818	663	450	444
South Haven:	671	532	343	336
Fennville:	665	522	333	329

Tree fruit

Insect activity increased last week.  We are now in the treatment window for Oriental fruit moth.  Few fresh plum curculio egg-laying scars were found.  Leaf roller larvae are feeding on the leaves and are common in some orchards.  Codling Moth Biofix was set as May 26 for most of the region.  For a May 26 biofix we are at 100 GDD50.  We expect codling moth egg hatch at 250 GDD past biofix, about next Monday. 

Apricots fruits are about one to 1 ¼ inches in diameter.  Bacterial spot lesions have been found.

Peach fruit are 16 to 19 mm in diameter.  The peach crop looks lighter every week, although some blocks have a good crop.  No Oriental fruit moth shoot strikes have been reported.  Oriental Fruit Moth was biofixed at SWMREC on May 4 at 310 GDD45.  Egg hatch should end at about 646 GDD45 after biofix (956 GDD45).  Peach fruit needs to be protected from rusty spot (powdery mildew) until pit hardening.  Growers can consider trunk sprays for lesser peach tree borer or greater peach tree borers after hand thinning is done.  A post harvest spray for borers can be done instead.  Pheromone disruption of these pests is also effective and eliminates the need to balance hand labor in the orchard with pesticide sprays and restricted entry periods.

Sweet Cherry fruit are about 16 to 18 mm in diameter.  Sweet cherries are always susceptible to brown rot.  Brown rot requires warm, wet conditions, 5 to 6 hours of wetness at 70F.  We may see warm and wet conditions this week when it rains. The rain event Friday was cherry leaf spot in Central Berrien and Southern Van Berrien counties, depending on where it rained.  

Tart Cherry fruit are 12 to 14 mm and the pits are hard.  The tart cherry crop looks pretty good.  The crop is throughout the tree, with lots of doubles.  Few fresh plum curculio egg laying and feeding scars were found.  Friday’s rain was a moderate cherry leaf spot infection for some areas. 

Plums: Japanese plums are about 16 18 mm.  European plums are about 14-16 mm.  Growers still need to protect against black knot and plum curculio.  

Apples fruit size is generally in the 14 to 18 mm range.  King fruit are generally 15 mm or larger.  Apple scab symptoms are very common on unsprayed trees and have also been found in sprayed orchards.  The new symptoms are probably from the May 14-16 infection period.  Friday’s rain was a moderate scab infection in Central Berrien and Southern Van Berrien counties.  We are near the end of primary scab season.  Almost all the scab spores have been released.  We need a good rain to bring the last of the spores out.  Scab protection will be necessary at least through the next rain event.  Last week’s cool weather kept bacterial populations low, so Friday’s rains were not fire blight infections.  Some growers reported canker blight symptoms of systemic fire blight, wilting stems near overwintering cankers.  Other growers also reported blossom blight symptoms Sunday.  We do not expect to see blossom blight symptoms from the May 26 infection until Thursday.

A few southern Berrien County orchards biofixed for Codling moth on May 14 at 278 GDD50, more commonly other orchards in the region Biofixed May 23 at 284.  We are at about 140 and 112 GDD50 after biofix for those two dates on Monday June 2.  Codling Moth Biofix was set as May 26 for most of the region.  For a May 26 biofix we are at 100 GDD50.  We expect codling moth egg hatch at 250 GDD past biofix, about next Monday.  The application timing of control materials varies greatly (see the article on codling moth in last week’s Fruit CAT Alert).  Spotted tentiform leafminer sap feeders are out and will form leaf mines soon.  European red mites are moving about.  San Jose scale adults are flying.  Sprays for San Jose scale crawler should be targeted for 300 to 530 GDD50 after biofix (June 1). Due to the cooler weather this year, sprays for crawlers will be a week or two later than last year.

We can now see initial fruit set.  Side fruits are about 2mm smaller than the kings.  Many growers applied thinning sprays but fruit set is still heavy and the thinners do not appear to have been very effective in the cool weather.  We have had several short (2 day) warm periods offering good apple thinning windows.  Apparently growers have applied their thinners too early in the cool periods (50-60F) before these windows.  The wet and windy weather forecast means that we will not have another good apple thinning windows until Thursday when conditions are good for spraying.  Unfortunately, the temperatures will be very warm in the mid to upper 80’s.  We recommend a moderate thinning strategy using 1/2 to 2/3 rates due to the very warm temperatures, which favor over thinning.  These high temperatures will high thinner doses very effective.  Use aggressive rates only with large fruit size (over 18mm), with heavy set and are lots of fruits in the cluster. 

Pears fruit are 12 to 14 mm in diameter.  The crop is variable.  Pear psylla adults and nymphs can be found in unsprayed trees.  Leaf and fruit symptoms of pear scab have been reported.  Growers should continue to protect against pear scab, through the next rain.

Small fruit

Blueberry bloom is ending.  There is still bloom in most fields as well as green fruit.    Many growers irrigated for Wednesday and Thursday mornings freeze when temperatures dropped below freezing in cold areas, especially where the soils were dry.  There were losses in cold sites.  Overall it looks like we will have a very large blueberry crop.  Growers with trickle irrigation should be irrigating.  It is hard to catch up with trickle irrigation when you fall behind.  Rainfall has been spotty and soils are dry.  Blueberries cay use 0.2 tenths of an inch of water a day or more in June and July when the sun is up from 6 AM until 9 PM.  A full-grown plant needs 4 gallons or more of water a day during the fruit growth.  For light sandy soils, frequent light irrigations of about an inch of water twice a week will wet the root zone and avoid leaching fertilizers and nutrients below the roots.  Leaves are greening up with the warm weather.  Trap catches of cranberry fruitworm and cherry fruitworm have been spotty.  These pests lay their eggs in the calyx cup of the fruit and no eggs have been found yet but growers have been applying Confirm and BT formulations.  These applications are too early.  Cranberry fruitworm biofix was expected at about 350 GDD50 with egg hatch following at 85 GDD50 after biofix.  Only the warmest sites in the region have 485 GDD50.  Growers should scout for eggs in the calyx cup of fruit.  Sprays of bee safe materials are planned when the weather warms up if there is still open bloom and bees are in the field.  Post bloom fungicide sprays should target anthracnose.

Grapes growth increased dramatically with warmer temperatures.  Freeze damaged vineyards still look pretty raged.  Concord and Niagara shoots vary a lot; primaries are 16 inches or longer, secondary shoots are about 12 inches, sprouting from the base of primaries live primaries.  New shoots from the base of the canes are 4 to 8 inches long.  Many primary shoots have 3 clusters.  Shoots in mechanically pruned vineyards are shorter and generally only have 2 clusters.  Secondary and tertiary shoots have one or two flower clusters.  There has been no growth from nodes killed in the April 30 freeze.  Flower clusters on primary shoots are beginning to elongate and the flower clusters are separating.  Wild grapes are beginning to bloom and Concords and Niagara will follow as soon as the weather warms later this week.  Growers need to apply their prebloom fungicide sprays to control bloom infections.  The conditions generally have been too cool for powdery mildew and, downy mildew.  Friday’s rain was a black rot infection in many areas and also probably a good phomopsis infection too.  Phomopsis lesions have been reported at the base of this year’s shoots.  We are trapping grape berry moth, but controls can be delayed until the first post bloom spray.

Strawberry bloom is ending.  Primary fruit are an inch or more in diameter and starting to color. The secondaries have thimble-sized fruit.  Pre harvest fungicides should be applied to reduce fruit rots such as gray mold.  Early harvest may begin this weekend.

Raspberry flower buds are separating in the cluster.  Early varieties such as Prelude and Nova are starting to bloom.  In Blackberry bloom has begun in early varieties such as Washita.  Primocanes in fall bearing raspberries are 12 to 18 inches tall.

Cranberry shoots are elongating and flower buds are visible.  Active growth before bloom is time for a protectant fungicide spray to protect new foliar and reduce fruit rots.

Miscellaneous

The next Monday Fruit Update meeting will be, Monday June 9, at the Fruit Acres Farm in Berrien County.

There is a Blueberry IPM meeting this Wednesday June 11 at Cornerstone Ag. 01240 57th Street, north of Phoenix Road, west of Grand Junction. 

A series of twilight grape scouting IPM meeting will start in two weeks. The dates and locations are: June 19 at Tim Seppala's farm, southeast of Lawton; July 24 at Bob Dongvillo's farm, south of Scottdale; and August 28 at Lemon Creek Vineyards, west of Berrien Springs. These meetings start at 6 PM.  For more information on these meetings call Mark Longstroth at (269) 675-8313.