SW Michigan Fruit Update

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Southwest MichiganFruit, May 14, 2007

Mark Longstroth, Bill Shane, Greg Vlaming

Weather

Last week was pleasant with lows in the mid 40s and highs in the upper 60s and 70s.  We had thunderstorms and rain, Wednesday morning May 9, 2007, causing infection by most fruit diseases.  We had a long warm wetting event with fog and the next morning we had fog and heavy dew.  The resulting wet period spanned over 30 hours, with about 24 hours of leaf wetness and an average temperature of 60F.  Precipitation totals were about a third to a half inch of water. But windy conditions have dried the soils.  Monday, May 14, was warm, over 80.  Thunderstorms are possible Tuesday.  This week’s forecast is for cool weather with lows in the 40s and highs near 60 with cooler temperatures forecast for rest of the week.

Southwest Michigan Growing Degree Days (GDD) Totals March 1 through May 13, 2007				Grapes from April 1
Location	GDD 42	GDD 45	GDD 50	GDD 50
Scottdale	704	572	388	281
SWMREC	672	542	364	266
Bainbridge	666	541	365	264
Hartford	656	525	350	255
Lawton	738	607	421	284
Grand Junction	731	581	397	278
South Haven	609	484	327	234
Fennville	598	471	308	228

Tree fruit

The May 9 rain was an infection period for apple scab, cherry leaf spot, and brown rot in stone fruit.  Plum curculio egg laying scars have been found in stone fruit.  Plum curculio activity should fall off with the cooler temperatures this week and return with warmer temperatures.  Insecticide applications should be targeted for later in the week when temperatures warm back up.  We are catching American plum borer and lesser peach tree borer. 

Peaches are out of the shuck and fruit are up to 14 mm in diameter.  The peach crop looks better and better.  Large numbers of Oriental fruit moth adults are still being caught in pheromone traps.  Egg hatch began May 5, 2007.  No peach leaf curl has been reported.  Grower should protect susceptible varieties from peach mildew or rusty spot.  Tarnished plant bug damage can be found on fruit.  Pheromone disruption of LPTB also suppresses GPTB.  This tactic works best in large homogeneous blocks.

Tart cherries are out of the shuck.  Fruit are about 10 mm in diameter.  Now that the fruit is clearly visible the crop looks much better.  Growers need to protect against plum curculio.  Growers need to assess their crop and determine if the amount of cherries available warrants a full pesticide program or a reduced spray program to maintain the leaf canopy and suppress cherry leaf spot.  Conditions for plum curculio will be marginal after Tuesday until it warms up but with a light crop growers cannot afford to lose any fruit.  Copper is an effective protectant material to reduce cherry leaf spot but it needs to be applied before a rain and growers should avoid multiple applications without rain, which would lead to a build up of copper on the leaves and result in toxicity even in tart cherries.

Sweet cherries are out of the shuck.  Fruit are about 12 mm in diameter.  Growers need to protect against plum curculio.  Sweet cherries should be protected from brown rot from bloom until harvest and the possibility of warm wet rains exist this week.  Copper should not be used on sweet cherries.  .

Plum fruit are about 12 mm in diameter.  Growers should be protecting against black knot and brown rot. 

Apple bloom is ending.  Fruit are 8 to 12 mm in diameter.  Warm temperatures on Monday raised the bacteria population to high levels and rain Tuesday could cause fire blight blossom infections of open flowers.  We are updating our Code-A-Phones daily with fire blight conditions.  Blossom blight symptoms should begin to appear next Monday.  Streptomycin symptoms are appearing in susceptible apple varieties for last week’s fire blight spray.  Conditions this week will be too cool apple thinning.  Growers should assess their crop and be ready to thin when highs begin to rise this weekend or next week.  Apple scab symptoms can be found from the April 26 infection.  The Enviroweather website. http://www.enviroweather.msu.edu/ is forecasting that all the apple scab spores are mature but not all have discharged.  Growers should maintain fungicide protection through the next good rain.   Oriental fruit moth is being caught in good numbers in pheromone traps.  Egg hatch began May 5, 2007.  Codling moths began flying May 5, and were biofixed on Wednesday, May 9 in some locations, but the flight has been very spotty, light and variable. Unless you are sure you have biofixed with a sustained flight of moths you should wait to apply codling moth controls.  It is entirely possible that many orchards will not biofix until next week because of the cool evening temperatures.  Codling moths controls are applied at 100, (Rimon and Esteem, with residue under the egg) 150 (Proclaim Intrepid, Assail, Calypso, and Clutch, with residue over the egg) or 250 (Guthion, Imidan, Warrior etc., which are targeted for contact kill of the emerging larvae) growing degree-days after biofix.  See the Enviroweather codling moth page.  Obilquebanded leafroller larvae are feeding in shoot tips.  European red mites and rosy apple aphids are out and growers and scouts should be looking for sap feeding spotted tentiform leafminers and the first mines.

Pear fruit are 10 mm in diameter.  Very little bloom remains but growers should protect against fire blight.  Pear psylla nymphs are feeding in the axils of leaves.  Pear blister mite symptoms have appeared.  Pear scab is similar to apple scab and pear scab symptoms should appear this week as with apple scab.

Small fruit

Blueberries are at full bloom and bees are very active.  Mummyberry shoot strikes are appearing.  The May 9 rain was an infection period for mummyberry.  Growers should check the new Blueberry IPM Newsletter at the MSU Blueberry Site.  Both cranberry and cherry fruit worms were reported caught in pheromone traps. Obilquebanded leafroller larvae are feeding on fruit buds.

Grapes: Concord shoots are about 6 to 10 inches long and flower clusters are elongating.  Vinifera have 4 to 6 and French hybrids have about 4 to 8.  The rain we had May 9 was an infection period for powdery mildew, black rot and phomopsis in grapes.  Growers have been applying early season disease control materials.  This first fungicide spray is especially important for phomopsis control.  Growers should apply protectants before the next rain.  Large numbers of grape berry moth are still being trapped but no treatment is necessary at this time.  Check the MSU Grape website for scouting updates.

Strawberries are at full bloom.  Given the dry conditions growers should be irrigating and applying bloom fungicides.

Raspberries: Summer raspberry flower buds are visible.  Fall raspberry shoots are about 6 to 12 inches high.  Blackberries and summer raspberries are showing more decline due to winter cold and the Easter freeze.

Cranberry buds have burst and are elongating.  Now is the time for the first fungicide treatment.

Miscellaneous

Soils are dry and growers should irrigate if they can.  Some fruit plantings from last year look stressed this may be a result of the winter cold snaps.  Herbicides applied to dry soils or drought stressed weeds are less effective.

 

The Van Buren County MSU Extension Office is moving and there is a new number for the Paw Paw Code-A-Phone.
The new Code-A-Phone number is 657-8217.  
You can use the old office phone number 657-7745 to contact Mark Longstroth until it is changed.

The next Monday Fruit Update meeting will be Monday May 21, 5 pm, at the Fruit Acres Farm in Berrien County.  We will discuss apple thinning.  The next Grape IPM meetings are Thursday May 24.  The morning meeting will be from 10 AM to noon at the Cronenwett Farm Shop at 70123 28th Street east of Lawton. The afternoon meeting will be at 2 PM in the Berrien County MSU Extension Office at the Southwest Michigan Research & Extension Center.  These meeting are co-sponsored by National Grape Cooperative and MSU Extension and are open to all grape growers.  There are RUP credits available for both the Monday Fruit Updates and the Grape IPM meetings.