WEATHER
By Jim Nugent, District Horticulturist, MSU-E

For the second week in a row, a major storm came through early Monday night. Last night, rainfall in the Traverse City area was much higher than previous rains this year. Winds were again very strong. Rainfall at the NWMHRS last night was 3.30", and the total for the week was 3.57". The total rainfall for June was 2.97". 

Evaporation this past week was estimated at 1.44" (our evaporation pan overflowed last night, so Monday's evaporation was estimated). Evaporation total for June was 6.51", which is actually less than the 17 year June average by 0.46". This probably occurred because while the total precipitation was less than average for the same 17 year period by 0.44", we actually recorded measurable precipitation on 13 out of the 30 days, thereby reducing evaporation during those days of rainfall.

GDD 50: 1053; GDD 42: 1699

GROWTH STAGES

Apricot: Harcot – 36mm
Plum: Stanley – 23mm
Apple: Red Delicious - 42mm
Sweet Cherry: Napoleon – 20mm
Tart Cherry: Montmorency – 20mm
Grapes: Buckshot berries 

INSECTS
By Gary Thornton, District Fruit IPM Agent

Apple maggot - The first adult catch in the abandoned orchard occurred last week. It was also reported by a scout in a commercial block near abandoned apples. Growers who are not scouting have 7-10 days after first flight before they have to have an insecticide on their apples, as the apple maggot adults only feed during this time. By July 7 to 10 the adults should begin laying eggs and an insecticide should be on by then. If growers are scouting for apple maggot they should get their red spheres out ASAP. Alternate row applications of insecticides work very well in controlling apple maggot.

Codling moth - Trap catches are down this week. We are in between generations, although some orchards can still experience high catches. In approximately 2 weeks the second generation will start.

Two spotted spider mites continue to build. This week we are approximately 3.5 mites per leaf in the tart cherries at the station. Last night's rain probably washed some of the mites off the trees. The rain will help the groundcover to stay favorable for the mites, so they won't migrate to the trees. 

Cherry fruit fly adults continue to migrate into commercial orchards. Cherry fruit fly maggots have been found in untreated sweet cherries here at the NWMHRS.

Plum curculio larvae are mature and continue to drop out of the cherries to pupate. 

Apple leafminer - A new pest to me, but apparently it has been observed in scattered in NW Michigan. Mining was observed on apples and occasionally in tart cherries. The pupa is unique, in that it is suspended in silk on a lower leaf.

Spotted tentiform leafminer - tissue-feeding mines are now observed in apples.

DISEASES

Cherry leaf spot - a heavy infection occurred last week on Thursday, ending on Friday morning. Last night's rain resulted in a light infection period. Growers should be sure to continue to control diligently for cherry leaf spot, as it is only early July. There is an abundance of inoculum, and new growth is still occurring. The young leaves are the most susceptible to infection.

Brown rot is now very common in untreated orchards. Growers should be very concerned about this disease, with all the wind whip and damage that can be found in both tart and sweet cherries. Full cover sprays with an appropriate fungicide are advised in all blocks. Alternaria can also be found on sweet cherry, particularly on cracked fruit. Indar, Orbit and Elite do not protect against this fungus. Rovral would be the best choice if Alternaria is a concern. Beware of the 7-day PHI for Rovral.

ETHREL LOOSENER

Temperatures appear to be close to ideal in the next few days for applying loosener.  Ethrel has a 7-day PHI now.

NW Michigan Horticultural Research Station
Insect Trap Count Averages - 1999 
 

DATE	Codling Moth	Spotted Tentiform Leaf Miner	Lesser Peach Tree Borer	Greater Peach Tree Borer	American Plum Borer	Oblique Banded Leafroller	Grape Berry Moth	Dogwood Borer
5/18	0	660	8		30
5/24	0	88	1.3		14.3	0
6/1	.6	85	17		4.6	0	9
6/8	2	15	17.3		2.7	0	7.7
6/14	1	342	11	6	.3	7	4.3
6/21	.33	511	10	5	0	2.3	1
6/28	.75	455	6.3	1.6	.75	2.3	16.3	10.6
7/5	0	357	7.3	1.6	2.6	0.3	2.3	7

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

Last Revised:7-6-99