SW Michigan Fruit Update

Check the Index for earlier postings

June 5, 2006

Bill Shane, Mark Longstroth

Weather

Last week cooled off.  Highs fell from the 90s to the 70s (close to the lake) and 80s ( inland) early in the week.  Scattered rain fell Tuesday and strong thunderstorms hit the inland counties Friday. Topsoils are dry near the lake but with good moisture away from the lake.  Soil temps are in the 70s.  This week’s forecast is for warm weather with highs in the 70s and chance of thunderstorms, with a cooler weekend.  The GDD below are from the Enviroweather site.

 

Southwest Michigan Growing Degree Day Totals March 1 through June 5, 2006				Grapes, from April 1
Location	GDD 42	GDD 45	GDD 50	GDD 50
Scottdale:	1017	832	571	541
SWMREC:	982	789	506	474
Bainbridge:	1046	848	575	541
Hartford:	922	741	494	467
Lawton	966	803	567	552
Grand Junction:	1051	857	592	555
Fennville:	911	727	480	452

Tree fruit

Plum curculio egg laying scars became much more abundant this past on plums, cherries, nectarines and peaches. 

Rose chafer beetles appeared at numerous locations over the past week, approximately the same timing as the last two years

Apricot fruit are 1.8 inches in diameter.

Peach fruit are 1.25 inches.  Oriental fruit moth (OFM) trap catches are high but are expected to decrease with the end of the 1^st generation.  Flagging of peach terminal by OFM is still relatively minor so far but with more egg hatch to go could yet be a problem. Plum curculio and tarnished plant bug damage to fruit have become easier to find.  This can drive the bugs into the tree canopy to feed on the fruit.  We are catching lesser peach tree borer adult moths. Trunk spraying for borers is customarily done in June.  Rusty spot , which is caused by the same fungus that causes apple powdery mildew, is showing up as white circular spots on fruit.  Fruit are susceptible to new infections of this disease until approximately pit hardening.

Sweet cherries are 18 mm fruit and some varieties such as Summit are beginning to show color.  The crop has been self-thinning over the last few weeks. Plum curculio egg laying scars have become easy to find in some orchards.  Leaf spotting and water-soaked spots on fruit from bacterial canker are fairly common on susceptible varieties such as Schmidt and Hardy Giant.

Tart cherries are at 14 mm fruit.  Growers need to protect against plum curculio and cherry leaf spot.  Leaf yellowing, black spots and shot holing of leaves due to bacterial canker can be found in some sites.  These symptoms can be confused with cherry leaf spot symptoms which are relatively rare so far.   

Plumsare at 18 mm fruit and pit hardening has begun?  The crop has thinned over the last week and is quite light in many sites.  Growers need to protect against plum curculio and to maintain protection for black knot until new growth ceases.  Symptoms from black knot infection this year become obvious next year.  White apple leafhoppers are causing stippling of the leaves.

Apple fruit are 20 to 25 mm in diameter and there is a wide variation in size between varieties.   Significant fruit drop from thinners and natural abscission occurred in many SW orchards this past weekend.  The last opportunity for thinning is approaching fast.  Growers need to protect against plum curculio and tarnished plant bug.  Apple scab symptoms are very common on fruit and leaves in unsprayed orchards.  Our scab model predicts that overwintering primary scab spores are mature, but a final good rain may be needed to release these spores from the orchard floor.  Growers need to maintain scab protection if they find scab lesions in their orchards.  Growers should continue to protect against powdery mildew.  Fire blight symptoms and bacterial ooze can be found on blighted terminal shoots, probably due to infection from oozing cankers, rather than blossom blight.  Trauma blight could be a problem if we get severe weather in orchards with oozing shoots.  Oriental fruit moth catches are stable and codling moths trap counts are up.  A regional biofix for codling moth occurred on Thursday May 25 to May 29^th, depending on the site.  Codling moth Biofix at SWMREC was at 328 GDD base 50.  A few orchards had enough codling moth catch on May 10 or 11^th to biofix at that time.  You can monitor the GDD model for these pests at the Enviroweather site.  See the article on pesticides for codling moth in the Fruit CAT Alert.  Obliquebanded leafroller are being caught in the area.  Other regions are report high numbers of European red mites in some areas so growers should scout their hot spots.

Pear fruit are at 18 mm.

Small fruit

Blueberries are ending petal fall with prospects for a very good crop.  Many growers are reporting the collapse of shoot tips and flower clusters in some fields.  Suspected reasons are frosts or disease.  Phomopsis tip dieback and cane collapse have been identified as well as botrytis and anthracnose.  Frost is the likely candidate where only the flower petals or terminal flower clusters are affected and there is no disease movement. mummy berry and anthracnose fruit rots.  Cherry fruitworm and cranberry fruitworm are being caught in pheromone traps.  Eggs of these two insects are very common now.  See the article on these fruitworms in the Fruit CAT Alert.  Growers should be ready to treat for these pests at the end of bloom.  Post bloom sprays also control blueberry gall midge and blueberry tip borer.

In Grapes, The last two weeks have brought rapid growth of new shoots so that many vineyards are finally greening up.  Bloom on wild grapes was noticed this past weekend.  Bloom of Concords in commercial orchards is expected this week on primary shoots that escaped the freeze. Secondary and tertiary shoots are 6 to 8 inches long.  At least 75% of the new growth does not have flower clusters and it looks as if most of the acreage will have less than a ton per acre.  In addition these shoots are about a month behind the primary are may not mature before the fall frosts. 

Strawberries fruit are beginning to color and early harvest has begun. 

Raspberry and blackberry bloom is underway.  Growers should be scouting for leafrollers.

Cranberry buds are beginning to burst.

Miscellaneous

The next Monday Fruit Update meeting will be, Monday June 12, at the Fruit Acres Farm in Berrien County, at 5 PM.