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

June 18, 2002

GROWTH STAGES
Apple: Red Delicious—12mm fruit
Pear: Bartlett –12mm fruit 
Sweet Cherry: Napoleon – 13mm fruit
Tart Cherry: Montmorency – 13 mm fruit
Plum: European type – 6 mm fruit
Grapes: Chardonnay – 10"-16" shoots

WEATHER

This past week was cool and wet, with rainfall occurring three or four days during the week. The wetting events in NW Michigan ranged from 53 to 127 hours, depending on location. Rainfall for the week at the NWMHRS totaled 1.81 inches.

COMMODITY REPORTS

Apples: Apple scab lesions are visible in unsprayed orchards. Last Friday and Saturday's heavy infection period marked the end of the primary season for apple scab. Growers who have scab present in blocks should maintain a protectant program to keep the scab off the fruit. Fireblight strikes are showing up from the rains that we had 15 days ago. Strikes should be cut out in young blocks, either by breaking them out or cutting them out and leaving a stub. Codling moth trap catches averaged three per trap at the NWMHRS. Some growers went over threshold early last week when the temperatures were warm. If growers are not trapping, they should plan on spraying for codling moth about June 26^th to control newly hatched larvae. Plum curculio is active in apples. Pressure may be higher in apples this year, as adult plum curculio adults search for ovipositional sites. Spotted tentiform leafminers are between generations. European red mites are above threshold in many blocks, and some growers have already applied miticides.

Cherries: It's hard to find tart cherry trees with enough fruit to justify harvest. Plum curculio is a threat in all stone fruit crops…where crops exist. If crops are non-existent, insecticides need not be applied. However, if trunk sprays for borers have not been applied where needed, they should be applied as soon as possible. Cherry leaf spot infections are common. This past weekend the rains resulted in a high infection period. Yellow leaves will start to show up next week from cherry leaf spot and sour cherry yellows. Be careful not to confuse the two. Leaves with cherry leaf spot will often have white mycelia on the under side.

Grapes should be getting a very important fungicide spray 10-14 days before bloom. This spray is important to control powdery mildew, black rot and phomopsis. Potato leaf hopper and rose chafer could show up anytime now.

Please send any comments or suggestions regarding this site to: 

Bill Klein, kleinw@pilot.msu.edu
Last Revised: 6-18-02