SW Michigan Fruit Update
August 9, 2005
Weather
Last week’s weather was hot and dry with highs in the upper 80s and lows near 60. There was no significant rain. Drought stress symptoms are wide spread throughout the region. Soil temperatures are in the 80s. This week’s forecast is for cooler weather with occasional chances for rain.
Southwest Michigan Growing Degree Day Totals
|
Grapes
|
|||
Location |
GDD 42 |
GDD 45 |
GDD 50 |
GDD 50 |
2931 |
2572 |
2015 |
1993 |
|
No data since August 1 |
||||
2751 |
2397 |
1849 |
1829 |
|
2975 |
2615 |
2056 |
2031 |
|
2764 |
2414 |
1872 |
1852 |
|
Tree fruit
Trap catches were down last week, following high trap catches the last week of July which was a cool week with rain on the 26th We are catching more apple maggot and blueberry maggot. Japanese Beetles are still common in some areas. Aphid and mite numbers are high in many crops. The second generation of Codling moth and the third generation of Oriental fruit moth are flying. Obliquebanded leafroller trap catches are up. Redbanded Leafroller trap catches are down.
Peach harvest continues with Red Haven harvest. Oriental fruit moth trap catches are up indicating the start of the third generation. We set Biofix as July 27 at 2259 GDD base 45 at SWMREC. Treatment is timed for 8 to 10% egg hatch at 150 to 170 GDD base 45 after Biofix about 2410 to 2430 GDD and egg hatch will continue to about 3200 GDD base 45. Brown rot is showing up here and there. Two spotted spider mites are a problem in some peach blocks.
Cherry growers should protect against cherry leaf spot. Some growers are pruning cherries. Japanese Beetles are common in cherries and causing damage in young planting. European chafers have also been reported in cherries???
Plum growers should protect against apple maggot and brown rot.
In Apples, we are catching more apple maggots. August is usually the month for this pest. See the Fruit CAT article on apple maggot monitoring and control. At this time most growers are applying pesticide sprays every two weeks. We biofixed on codling moth July 20, at 1581 GDD base 50. We are now at 2015 GDD. Many growers treated last weekend and trap catches are down. Trap catch for Obliquebanded leafroller was down last week. We expect the next generation to emerge this week at about 2935 GDD base 42s. Redbanded Leafroller flight is low. See the article on summer leafroller control in the June 21, 2005 Fruit CAT Alert. Oriental fruit moth trap catches are up indicating the start of the third generation, see the notes under peaches. European red mite numbers are exploding and many growers have applied one or more treatments. If you have seven mites per leaf you should control European red mite. Late season pyrethriods, such as Danitol, can reduce mite numbers but also knock down predators and almost always result in heavy mite pressure late in the season and a large overwintering population of mites. The mines of the second generation of Spotted Tentiform Leafminer are showing up. Growers should be scouting for white apple leafhopper nymphs. Examine 50 leaves from 10 different trees and treat if the average is more than one nymph per leaf.
In Pears, European red mites and pear psylla numbers are building. Growers should be protecting pears from the second generation of codling moth.
Small fruit
Blueberry: Growers have harvested the third picking of Bluecrop and second picking of Jersey. Elliot harvest has begun in the south. In non-irrigated fields harvest has ended early due to poor fruit size and quality. Blueberry maggot and Japanese Beetles are out. Tussock moth larvae are a problem in some areas. Rufus Isaacs had an article on blueberry insecticides in the June 28 Fruit CAT Alert. Blueberry aphid numbers are low. Harvest fungicides should target Alternaria fruit rots. See the article in June 14 Fruit CAT Alert.
Grape veraison has begun in early varieties and
early sites. Grape berry moth
flight and egg laying increased sharply last week indicating the beginning of the third
generation flight. Insecticide sprays to control egg hatch should be applied. See the
article in the July 26 Fruit CAT alert on “Controlling mid-season grape berry
moth.” Disease pressure this dry summer has been light. We have found powdery mildew symptoms on Concord fruit but
not much downy mildew. Downy mildew is
the disease we are worried about at this time. See Annemiek Schilder’s article on late season grape disease control
in the July 26 Fruit CAT Alert. The timing
for controls of phomopsis and black rot has passed. Fruit rot symptoms of black rot have been found but the fruit is
becoming more and more resistant as we approach veraison.
Strawberry growers should protect against leaf diseases and potato leafhopper.
Summer Raspberry harvest is ending. The fall raspberry, Autumn Bliss is being harvested. Blackberry harvest is underway and some growers are reporting white druplets from the heat.
Miscellaneous
Now is the time for tissue sampling to determine fertilizer needs in fruit plantings.