SW Michigan Fruit Update
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Southwest Michigan, August 11, 2009
Weather
The last two weeks were warm with highs near 80 and lows in the 50s. The weekend was hot with highs over 90 on Sunday. The passage of warm and cool fronts caused thunderstorms on Friday, Saturday and Sunday, which dropped from a third to over an inch of rain. Soils good moisture content and field crops look much better. We continue to lag about 10 days behind normal in heat units accumulated. Fruit crop development seems close to normal.
Southwest
Michigan Growing Degree Day Totals
|
Grapes, April 1 |
|||
Location |
GDD 42 |
GDD 45 |
GDD 50 |
GDD 50 |
2661 |
2282 |
1696 |
1646 |
|
2457 |
2090 |
1519 |
1493 |
|
You can find weather and IPM information for Southwest Michigan at the Enviroweather website.
Insects
Japanese beetle numbers have increased with hot weather and rain. We expect apple maggot and blueberry maggot numbers to increase after this weekends rain showers. Potato leafhopper damage is easy to find. San Jose trap counts at Trevor Nichols started increasing on July 27, (1257 base 50 from March 1), which is about the right time for the next generation. Crawlers are expected approximately 500 degree-days base 50 following this, or at about 1757 DD50 from March 1. There are probably already crawlers out in Southwest Michigan orchards.
Tree fruit
Peach harvest continues with the yellow flesh types Red Haven, PF11, Blazing Star, and Starfire. Red Haven harvest in Berrien County began on approximately August 6th, a few days later than the projected date of August 3rd. Fruit size on early varieties has suffered due to dry conditions in southern end of growing region. Fruit flavor is generally very good. Brown rot can be found sporulating on fruit, in mummies, and blighted twigs. It is important to remove these after harvest to reduce the inoculum for the beginning of next season. Fungicide treatments for brown rot are needed as fruit color. Bacterial spot symptoms continue to increase especially for susceptible varieties growing in sites exposed to wind-blown sand. Summer dews are conducive to bacterial spot. Oriental moth catches are low but fruit entries from this past generation are becoming more obvious. Oblique-banded leafroller larvae are causing shallow feeding damage on peach fruit. A trap catch increase last week indicates that next generation flight is starting. Watch for signs of western flower thrip on peaches. Thrip damage appears as light brown fuzzless spots up to 1 inch in diameter usually on the blush region.
In Plums,Vibrant, Castleton, and Early Italian harvest is underway. Ripening plums should also be protected from brown rot. Pitting and gumming is fairly common on some European plum fruit varieties due to bacterial canker in early June. Apple maggot is a problem in ripening plums and we can expect a strong flight following the weekend rain. Scout for leafhopper damage from white apple or potato leafhoppers.
Apple fruit size and quality still look good. Zestar, Chenango and Dandee Red harvest to start this week. Paula Red harvest should begin in about 10 days. Fireblight is not spreading due to the dry conditions. The second generation of codling mothis flying, and should peak in mid August. Oriental fruit moth trap catches are low. Apple maggot flies are out and we expect a strong flight following the rain. Obliquebanded leafrollertrap catch increased last week indicating the start of the next generation flight. Apple aphids are easy to find. Bronzing due to mites is fairly common. The treatment threshold for European red mite in July and August is more than 7 mites per leaf. Young tree growth has been hampered by dry conditions.
Pears are over 2 inches in diameter. Pear Psylla populations are building in some blocks causing sooty appearance and honeydew symptoms on leaves near veins. European red mites are causing black leaves in some blocks. Growers should protect against the second generation of codling moth, which emerges in late July through August and attacks pears just before harvest.
Small fruit
Blueberry harvest continues with hand and machine harvest of Jersey. Fruit size and quality are good in irrigated fields. Blueberry maggot numbers have increased after this weekend’s rain. Anthracnose and alternaria fruit rots are fairly common. Growers should maintain protection against alternaria fruit rot and blueberry maggot. Phomopsis cane collapse is common. No treatment is effective at this time. These should be pruned out and removed from the field. For more information look at the Michigan Blueberry IPM Newsletter posted by Paul Jenkins at the Berry Entomology Lab.
Grapeswill probably benefit the most from this weekend’s rain and warmer weather. Veraison has begun in early varieties. Generally there were few disease infections since bloom. The window for treating black rot and phomopsis has passed. Phomopsis lesions are easy to find on stems and clusters in some vineyards. Powdery mildew has been found on wine grape varieties. The diseases of greatest concern now are botrytis and downy mildew. Botrytis symptoms can be found in scouted vineyards. Morning dews are good for the spread of downy mildew, so fungicides against downy mildew are required during the summer season when there are morning dews. Grape berry moth eggs are hatching and stings and tunnels can be found on the fruit. Japanese beetles numbers are up following this weekend’s rain. See the most recent copy of Grape IPM Newsletter at the MSU Grape current conditions webpage.
Strawberry growers should control potato leafhoppers to prevent stunting of new growth.
Fall raspberry harvest has begun in early varieties. Green June beetles and Asiatic garden beetles have been reported in raspberries. Morning dews can cause fruits rot problems such as Botrytis gray mold, so fungicides are needed when there are morning dews.
Meetings
The last grape IPM evening meeting of the season is this Thursday evening, August 13 at Lemon Creek Winery, 533 East Lemon Creek Road, east of Berrien Springs. There is no cost for the meeting. The meeting begins with dinner at 6:00pm followed by a tour of the IPM plots in the vineyards. The meeting will wrap up around 8:30pm. One RUP credit is available for the meeting.
