SW Michigan Fruit Update
Check the Index for earlier postings
Southwest Michigan, June 9, 2008
Weather
Summer arrived last week. Temperatures rose into the 80s with lows in the 60s. Heavy storms passed through the region Friday, Saturday and Sunday. These storms brought heavy rains and high winds, blowing down trees causing local flooding and erosion. Hail also fell in many areas. Rainfall totals from these storms varied from a one to three inches. Allegan County received much more rain (almost 7 inches) than areas to the south. Most of these rains were disease infection periods. Heavy rains wash off protectant pesticides so growers need to reapply protectants or switch to systemic materials. The rains also restored soil moisture levels. We expect cool temperatures for a couple days. Expect warmer temperatures Thursday and Friday with highs in the mid 80’s and lows near 60. Our GDD totals are about 10 days behind 2007, 3 or 4 days behind average.
Southwest
Michigan Growing Degree Day Totals
|
Grapes, from April 1 |
|||
Location |
GDD 42 |
GDD 45 |
GDD 50 |
GDD 50 |
1032 |
851 |
600 |
590 |
|
1020 |
841 |
589 |
581 |
|
952 |
782 |
545 |
539 |
|
972 |
803 |
566 |
559 |
|
926 |
761 |
532 |
528 |
|
1030 |
852 |
599 |
594 |
|
1039 |
863 |
615 |
609 |
|
887 |
727 |
503 |
496 |
|
868 |
705 |
480 |
476 |
|
Tree fruit
Deer browsing has been severe in some young and newly planted blocks of trees. Insect activity increased last week with the warm temperatures. Fresh plum curculio egg-laying scars were found. Leaf roller larvae are feeding in some orchards. Potato leafhoppers arrived with the south winds from the weekend storms. Tarnished plant bug feeding damage has been reported in apples and peaches. Rose chafer and Japanese beetles are emerging. Obilquebanded leafroller adults were trapped Monday, indicating the flight of the overwintering generation. We are catching lesser peach tree borer. Trunk sprays or pheromone disruption are recommended for borer control.
Apricots fruits are about 1.5 inches in diameter. Bacterial spot lesions have been found.
Peach
fruit are about one inch in diameter. The peach crop looks better as fruit drop has
ended and the remaining fruit are clearly visible. Some varieties will need hand
thinning and others such as Red Haven have a light crop. Peach growers should
consider trunk sprays for lesser
peach tree borer or greater peach
tree borers after hand thinning is done. Pheromone disruption of these pests is
effective and eliminates the need to balance hand labor in the orchard with pesticide
sprays and restricted entry periods. Oriental fruit moth shoot strikes
have been reported. Egg hatch for the first generation of oriental fruit moth should
end this week. Peach fruit needs to be protected from peach scab and rusty spot
(powdery mildew). Peach fruit become resistant to rusty spot at pit hardening.
Sweet Cherry fruit are about 20 mm in diameter and early varieties are yellowing and showing red color. Bacterial canker symptoms, yellow leaves with large black spots, sunken hard cankers on the fruit and gumming from the bark are apparent in some orchards. There are no effective controls in sweet cherry this late in the season. Copper can be applied in the dormant season. The warm wet weekend was probably a good brown rot infection. Brown rot requires warm, wet conditions, 5 to 6 hours of wetness at 70F such as we had this weekend. The rains were also cherry leaf spot infection in some areas. Sweet cherry trees also need to be protected from the peach tree borers.
Tart Cherryfruit are 16 mm in diameter. The crop looks good. The weekend storms caused some damage in tart cherries where trees were blown down in older orchards. The rains were moderate to heavy cherry leaf spot infections. Bacterial canker symptoms can also be found on tart cherry leaves and fruit. Tart cherry trees also need to be protected from the peach tree borer complex.
Plums: Japanese plums are about 20 mm with good crops in some varieties and poor crops in others. European plums are about 18 mm. The crop looks good. Growers still need to protect against black knot and plum curculio. Plum trees also need to be protected from the peach tree borers. Thiodan or pheromone disruption are the only registered controls in plums.
Apples are growing vigorously and king fruit are 18 to 26 mm in
diameter. Fruit drop over the last week has been heavy and it is easy to see which
apples will fall. Some growers applied thinning sprays late last week to take
advantage of the hot weather. Generally drop has been heavy and in some varieties
the crop is very light.
The weekend storms marked the end of the primary scab season. Apple scab symptoms can be found in sprayed orchards. Growers with active scab should continue to protect against scab infection. As the young fruit becomes waxy it becomes more resistant to scab. Last week’s hot weather revealed fire blight infections. Growers reported blossom blight symptoms before the weekend storms, which were trauma events that could spread fire blight throughout the region as in 2000. Some varieties are losing their spur leaves. These leaves were damaged in the April 30 freeze and are being shed. We are also seeing frogeye leaf spot. This is a foliar infection caused by black rot.
Trap catch for codling moth increased. We are now in the treatment window for codling moth. Regional orchards biofixed for codling moth from May 14 to May 26. We reached 250 GDD50 for the last biofixes and egg hatch should be underway throughout the region. Spotted tentiform leafminer will form leaf mines soon. European red mites are moving about. San Jose scale adults are flying. Sprays for San Jose scale crawler should be targeted for 300 GDD50 after biofix (June 1), about June 20. .
Pears fruit are 18 to 20 mm in diameter. The crop looks good. Other than pear psylla there are few insect pests of pear. The second generation of codling month often attacks pears before harvest.
Small fruit
Blueberry bloom has ended. Small green pea-sized fruit cover the bushes. We have a very large blueberry crop. Controls for cranberry fruitworm and cherry fruitworm have been applied to many fields. Post bloom fungicide sprays should target anthracnose. Last week we found many examples of collapsed blossom clusters. We thought this was freeze injury but we see the damage only in low vigor Jersey bushes. We believe these are phomopsis infections of the flower clusters. Most of the fields had good fungicide programs that should have reduced the disease. Shoestring virus and mosaic systems are easy to find. There is no cure for these diseases and infected plants should be removed to reduce the spread of these diseases.
Grapes bloom has begun. Concord and Niagara began to bloom late last week in southern Berrien County and trace bloom was seen near Paw Paw Monday. Wine grape flower clusters are elongating and beginning to separate. Heavy rains over the weekend would have washed most prebloom fungicide sprays off the vines. Growers should consider using systemic materials such as the SI materials, such as Nova, Elite and others and alternating with the strobilurins Abound or Flint. Phomopsis leaf and cane lesions easy to find. We are trapping grape berry moth, but controls can be delayed until the first post bloom spray.
Strawberry harvest has begun. Hot temperatures and rain have moved the crop rapidly. Some growers have applied copper to reduce angular leaf blotch.
Raspberries and Blackberries are blooming. Bloom fungicide sprays will reduce fruit rots. Primocanes in fall bearing raspberries are 12 to 18 inches tall.
Cranberry flower buds are visible and bloom should begin when we get a few hot days. Active growth before bloom is time for a protectant fungicide spray to protect new foliar and reduce fruit rots.
Upcoming Meetings
The next Monday Fruit Update meeting will be, Monday June 16, at the Fruit Acres Farm in Berrien County.
There is a Blueberry IPM meeting this Wednesday June 11 at Cornerstone Ag. 01240 57th Street, north of Phoenix Road, west of Grand Junction.
There is a twilight grape IPM meeting June 19 at Tim Seppala's farm, southeast of Lawton at 6 PM.
