Northern Michigan FruitNet 2005
Weekly Update
NW Michigan Horticultural Research Station

Jim Nugent                   Nikki Rothwell                Bill Klein
        District Horticulturist           District Fruit IPM Agent         Farm Mgr, NWMHRS

    Duke Elsner                                                    Jim Bardenhagen
            Agricultural Agent                                              Leelanau Extension Director

July 19, 2005

WEATHER

There has been a few spotty showers in the area this week, but nothing that brought substantial amounts and some areas received none. The NWMHRS was under a small rain cell on Sunday afternoon and consequently received 0.34" for the past week bringing the total since June 1 to 1.31".   2005 will be remembered for the severity of the drought.

CROP REPORT

Apples: A bit of apple scab has been reported in the Benzie County area, but most incidences are spotty at best. Fire blight strikes are evident around apple orchards in northwest Michigan. Codling moth trap (CM) catches remain steady compared with last week: 5 moths/trap. At the NWMHRS, we are a little over 1000 GDD past biofix for CM; we predict second generation CM egg hatch at 1,200 GDD. We captured 7 oriental fruit moths/trap this week, and spotted tentiform leaf miner catches are at a trap average of 300. Obliquebanded leaf roller traps captured 4.5 moths/trap this week. We captured no apple maggot on the yellow boards this week, but the red sticky spheres were placed into the orchard this Monday.

Cherry: Cherry leaf spot infections are very low. American brown rot is still popping up in sweet cherries that have yet to be harvested. We are still seeing powdery mildew in tart cherries, especially on the inner leaves. American plum borers are at 17 moths/trap. Lesser peachtree borer numbers are still low this week, but greater peach tree borers remain high at 21 moths/trap. We have placed dogwood borer traps. Two-spotted spider mite numbers are still high in cherry orchards; we are monitoring the numbers throughout the season to have a better understanding of mite population under hot, dry conditions. Cherry fruit flies are still showing up in the entomology block at the NWMHRS, but we have still seen low numbers in commercial blocks. 

The combination of hot and very dry conditions has resulted in substantial injury due to Ethephon application. Symptoms include leaf yellowing and drop, and exudation of a clear gummosis. If the drought continues to worsen, the potential for injury from Ethephon will increase. If trees are under severe drought stress, I believe the wisest course of action is to not apply Ethephon. Substantial defoliation at this time of year causes the tree to be very susceptible to limb or tree death this winter. The cost of leaving some fruit on the tree could quickly be eclipsed by the cost associated with tree decline or death.
 
 

Seasonal Evaporation & Precipitation
Beginning May 1, 2005, at NWMHRS
Date	Evap/week (in.)	75% of Evap/week	Rainfall/wk at NWMHRS (in.)	Rainfall minus 75% of Evaporation
5/2	0.31	0.23	0.01	-0.22
5/9	1.08	0.81	0.07	-0.74
5/16	0.76	0.57	0.53	-0.04
5/23	1.00	0.75	0.87	0.12
5/30	1.32	0.99	0.07	-0.92
6/6	1.60	1.20	0.05	-1.15
6/13	1.90	1.43	0.12	-1.31
6/20	1.15	0.86	0.30	-0.56
6/27	2.02	1.52	0.03	-1.49
7/4	2.15	1.61	0.45	-1.16
7/11	1.82	1.37	0.02	-1.35
7/19	1.62	1.22	0.34	-0.88
Totals	16.73	12.55	2.86	-9.69

This issue and past issues of the weekly FruitNet report are posted on our website at: http://www.maes.msu.edu/nwmihort/faxnet.htm

Please send any comments or suggestions regarding this site to: 

Bill Klein, kleinw@msu.edu
Last Revised: 7-19-05