Northern Michigan FruitNet 2002
Weekly Update
James E. Nugent      Gary E. Thornton       William M. Klein
NW Michigan Horticultural Research Station
Michigan State University

August 20, 2002

WEATHER

Much needed rain fell in NW Michigan during the past two weeks. Rainfall at the NWMHRS totaled 0.2" and 1.98" per week, respectively. Evaporation remained high for the same two week period at 2.13" and 1.61" per week. This past week was the first time rainfall has exceeded 75% of evaporation since the week ending 6/18 at the NWMHRS.

INSECTS & DISEASES
By Duke Elsner, EAA, Grand Traverse Co.

Cherry growers should find it easy to see adult cherry fruit flies (CFF) laying eggs in fruit in unsprayed, unharvested cherry orchards that have a source of adult flies. Some unsprayed blocks already have a very high percentage of the fruit currently infested by maggots or showing maggot injury. Expect heavy CFF pressure next year in blocks where some level of fruit was present in 2002. Blocks with no fruit present are likely to have very low CFF pressure next year. The same is likely to occur for plum curculio.

Last week’s big rain resulted in a heavy infection period of cherry leaf spot (CLS) fungus. Due to the toughness of old leaves, the symptoms of this infection will not likely appear until mid-September. From this point on it is probably not worthwhile to make any post-harvest treatments for CLS.

Apple growers need to be concerned about apple maggot (AM) and codling moth (CM). AM adults on traps have remained steady. Trap catches of CM have dropped off at the NWMHRS, but at certain orchards which are CM hot spots the trap counts are still well above threshold, and fruit damage is still a concern. The second generation of CM should end in the next few weeks. Spotted tentiform leafminer (STLM) trap catches are down, and new sap-feeding and some tissue-feeding mines are now present, but it seems that the numbers are light and there will be little need for control. A number of blocks in the area have sustained significant mite injury to the leaves, easily seen by simply driving by. Two spotted spider mite populations have gone up significantly in some blocks, but their normal fall drop in population should come in early September. European red mite numbers are high in some places. Watch out for these more, as they do not leave the trees in the fall – they will begin to lay eggs on woody tissues and in the calyx end of fruits soon. Green apple aphid is still common where there is active shoot growth, but the impact of predators is picking up. Keep a close eye on young blocks that might still have significant amounts of growing shoot tips. Pear growers should be checking for increased pear psylla populations, which have already appeared in a few blocks.

Peach and plum growers need to be on top of brown rot as harvest progresses. Brown rot threat increases rapidly as fruit ripening goes along. Post harvest quality of peaches is significantly improved by pre-harvest brown rot control materials. Plum growers also need to be concerned about apple maggot attack.

Grape growers are seeing the beginning of veraison in early varieties. So far, crop quality looks fairly good. Spider mites have increased to significant levels in some vineyards. Potato leafhopper numbers are down a bit, but this insect is still active and capable of impacting shoot growth, especially on young vines. Another threat to young vines are the giant caterpillars of sphinx moths– this is the season for finding the green or orange larvae with big white spots on their sides stripping the leaves from vines. Mature vines can tolerate a good deal of injury now, but vines in their first few growing seasons need to be protected from these caterpillars. 

THE TART CHERRY CROP

It’s time to close the record books on the 2002 tart cherry crop. Harvest (what little there was) concluded this past week in NW Michigan with the last of the Balaton. A harvest of 1 million pounds in NW Michigan goes into the records as the smallest crop since the keeping of records began in the 1920's. 

The significant short- and long-range impacts and implications of the record-low tart cherry crop will be presented and discussed in detail as part of the program for the Northwest Michigan Horticultural Research Station annual open house, Thursday, August 29^th. 

CIAB Weekly Raw Product Report

If you are interested in the CIAB weekly raw product report, it can be accessed at the following address:
http://www.cherryboard.org/prodrept.html

NW MICHIGAN HORT STATION OPEN HOUSE

This year's Open House will be held on Thursday, August 29^th beginning at 2:30 p.m. There will be no equipment show. The afternoon will begin with an hour-long program featuring the results to date of the studies on the effects of orchard floor management alternatives on cherry production. Discussion to include the influence of pests, beneficials, tree growth, yield, fruit quality and nitrate leaching. Starting at 3:45 there will be a section covering financial and other related information that is pertinent to this unique year with no tart cherry crop.

The program will be followed by a social hour and pig roast, sponsored by the Leelanau Horticultural Society. The pig was purchased and donated by the Paul and Frances Johnson Foundation. Cost for the dinner is $15 and tickets can be purchased at the door. The evening will wrap up with a short awards program.

WEEKLY EVAPORATION and PRECIPITATION REPORT
 

Please send any comments or suggestions regarding this site to: 

Bill Klein, kleinw@pilot.msu.edu
Last Revised: 8-20-02