WEATHER

Evaporation is up somewhat, totaling 1.09" over the past week at the NWMHRS. Last week's rainfall totaled 0.56". Evaporation exceeds rainfall by 5.35" for this growing season. 

GROWING DEGREE DAY ACCUMULATIONS as of June 6th at the NWMHRS

Year       2000      1999      1998      1997
GDD42    810        876         950        483
GDD50    391        465         518        210

GROWTH STAGES:
Apricot: Harcot -- 33mm
Plum: Stanley -- 12mm
Pear: Bartlet -- 16mm
Apple: Red Delicious -- 14mm
Sweet Cherry: Napoleon -- 12mm
Tart Cherry: Montmorency -- 12mm
Grapes: Chardonnay -- 4"-8" shoots

COMMODITY REPORTS

Some apple growers have already biofixed for codling moth, mostly in older trees with historically high numbers. Trap catches in the NW region range from zero to over 40 per trap. Green apple aphids are building on terminals. White apple leafhopper nymphs are present, as well as a few potato leafhopper adults. Plum curculio stings are common in unsprayed apples. European red mites are increasing in untreated blocks; some blocks are already treated. Predator mites are common. Apple scab has shown up in commercial orchards where spray schedules were light. Fireblight blossom blight is beginning to appear from earlier infection periods.

Pear psylla are now in the hard shell stage. Tarnished plant bug activity will pick up in peaches with the warmer weather.

Last week spurs and shoots on sweet cherries began collapsing in some lower areas of blocks. Heavy gumosis was common in the affected areas. The cause appears to be bacterial canker invasion of cold-injured tissue. This is a very unusual event that was induced by the combination of frost conditions followed by extended periods of cool, wet weather.

Cherry leafspot is common in untreated tart cherry orchards. Brown rot pressure remains low. Plum curculio stings are common in untreated stone fruits. For the postponed Insecticide Treatment Strategy (PTS) for tart cherry, we are currently at 216 DD base 50 after full bloom. According to the model, a spray is needed at 375 DD. This year growers are encouraged to be conservative and apply sprays early, due to the cool season. Insecticide sprays should go on by this weekend for the warmer areas of NW Michigan. Growers should also put out their cherry fruit fly traps. 

Necrotic ringspot virus (NRSV) is common in tart cherries this season, often appearing on 6-9 year old trees (slightly younger than normal). The symptoms include a stunting of growth with tattered, small leaves. This symptom is referred to as the "shock" symptom of NRSV, typically occurring on young bearing trees when it occurs. This was induced by an extended period of exceptionally warm conditions, which occurred during the period immediately before, during and slightly after bloom. Because of the timing of this heat wave, buds were beyond bud swell, so virtually no bud blast occurred this year. We often refer to the bud blast symptom as "red bud". Because of the lack of bud blast, we do not expect to see extensive die back, but limbs or trees affected are slow to begin growth and will not grow as well as normal. 

Miscellaneous

Please send any comments or suggestions regarding this site to: 
Bill Klein, kleinw@pilot.msu.edu

Last Revised:6-6-00