Mira Danilovich

Weather and crop development
Over the past two weeks weather has been very comfortable with high temperatures from the low 60’s to low 80’s and back into low to mid 70’s, and lows from the mid-40’s to low 50’s. There were a few showers at the beginning of the end of the two-week period. The National Weather Service is calling for possible scattered showers and thunder storms Tuesday night, July 14, and into Wednesday, July 15.

Sweet cherry harvest is underway and any rain at this time spells “trouble.”

Growing degree day totals from March 1 as of Sunday, July 12

Location	GDD 42	GDD45	GDD50	Rainfall last week	Rainfall for the period of April 1-July 12
Hart	1566	1271	904	0.13	12.54
Ludington	1438	1178	802	0.08	10.05
Bear Lake	1465	1211	844	0.12	10.21

The rain of July 1 resulted in moderate apple scab and cherry leaf spot infection periods in Oceana and Mason counties and heavy infections in Manistee County. The most recent rain of July 11 did not result in scab infection, however it did induce low cherry leaf spot infections in Manistee and Mason counties. Fire blight symptoms are scattered throughout the area with a higher degree of presence in southern parts of the district. Cherry leaf spot has been found sporadic but quite heavy in a few blocks. Powdery mildew could be found in many blocks.
In peaches, we are starting to find some of the “rusty” spots associated with powdery mildew. Upcoming rain is going to favor brown rot and alternaria development in sweet cherries particularly if fruit starts to crack.
Cherry fruit fly catch was reported on July 8. The cherry fruit fly was caught in a commercial block in Oceana County, just north of Hart. No reported catches elsewhere. This time of the season cherries need to be covered to prevent cherry fruit fly injury and “surprises” at the receiving dock. Rosy apple aphids and green aphids are still being found in high numbers.
Rose chafer and Japanese beetles are present and inflicting significant damage. No reported catch of apple maggot. Sweet cherries are being harvested and the tart cherry harvest is about five to seven days away. Keep the fruit protected. Lesser peachtree borer numbers have stayed unchanged since last week or about 50 percent fewer since two weeks ago. Greater peach tree borer numbers have dropped about 50 percent from a week ago. There was significant increase in codling moth numbers during the end of the week of July 4 and about 50 percent drop this week. They went from 3.8 to 5.2 per trap and down to 2.4 moths per trap. There has been accumulation of 659 GDD base 50 since the biofix in Hart and 557 GDD base 50 for the Ludington area. Since last week Oriental fruit moth trap catches have been decreasing from 1.77 per trap to 0.84 a week ago to 0.54 this past week. There has been a significant drop in obliquebanded leafroller numbers since last week. They have gone from 21.5 moths per trap to three moths per trap. Scouts report finding adult European red mites and eggs in moderate numbers. Pear psylla numbers are rising. There are reports of increased numbers of rust mites in both pears and apples. There is a healthy population of predatory insects (lacewings, lady bugs adults and larvae etc.) in the orchards throughout the area.