Southeast Michigan fruit regional report – August 12, 2014

Strong apple maggot catch on red sphere traps finally arrives for most apple growers, and spotted wing Drosophila trap catch continues to rise in raspberry and blueberry plantings.

Weather

Heavy, slow-moving rainstorms moved over the region Monday, Aug. 11, bringing much needed precipitation for most fruit growers and too much rain for some. Rainfall totals varied across the region with lows around 0.6 inches, most receiving close to 2 inches and a few areas receiving 3 to 4 inches. Rain over 2 inches can cause rapid shut down of root systems of shallow-rooted fruit crops like strawberries and raspberries. More details to follow in those sections of this report. There were no reports of hail in these storms.

Our season remains slightly behind normal to normal for growing degree day (GDD) totals for our region and ahead of normal in terms of beginning of harvest of our fruit crops. Although with the total loss of our peach and plums crops that would normally be harvested at this time, it is a bit difficult this season to determine the beginning of harvest of our wide variety of fruit crops we grow across this region.

Soil moisture supplies are now adequate at most farms from yesterday’s rain storms. Prior to this rain event, growers had been irrigating on a regular basis for the last three weeks.

East Michigan GDD totals for March 1 to Aug.11, 2014

Location

GDD42

GDD45

GDD50

Commerce (Oakland)

2,464

2,109

1,564

Emmett (St Clair)

2,494

2,140

1,600

Flint (Genesee)

2,761

2,348

1,785

Lapeer (Lapeer)

2,505

2,151

1,612

Petersburg (Monroe)

2,664

2,300

1,745

Pigeon (Huron)

2,329

1,991

1,473

Romeo (Macomb)

2,617

2,255

1,700

Tree fruits

Apples continue to have good fruit size this season, although sizing seemed to have stalled in the past week with many soils on the dry side until yesterday’s rains. Apples have put on a good amount of color over the last two weeks. Apples in the Flint, Michigan area are mostly 2.625 to 3 inches in size. Harvest of Earligold, Pristine and Paula Red will begin soon at farms with early maturing sites. We are approximately three weeks away from Gala harvest. Growers using Retain need to begin to schedule some applications three to four weeks prior to the beginning of harvest. Apples appear to be developing faster than we predicted in the predicted apple harvest dates published earlier in the season. The actual dates may be closer to normal or average. Summer pruning of apples continues. Leaf tissue samples for nutrient analysis need to be collected this week as the proper collecting window is closing in mid-August.

Apple maggot catch on red sphere traps finally started late last week and early this week at most farms – almost a month later than normal first trap catch. Growers have a week to cover for this flight, so I expect a good number of apple blocks will be covered this week. Trap catch numbers of codling moths have just started to decline a bit in conventional blocks and are near zero in most pheromone disrupted blocks. Oriental fruit moth trap catch is also starting to drop for the second generation adult flight. Many apple growers are finding a few fruit infested with codling moths and feeding damage from obliquebanded leafrollers this season compared to most seasons.

The mite hotspots seem to be greening up well as predators have controlled them nicely. I continue to find a few woolly apple aphids on terminals and fruit; these will need to be watched closely for the rest of the season. Japanese beetles continue to be seen in generally low numbers in all fruit crops. Predators are abundant this season, feeding heavily on mites and lately on green apple aphids.

Heavy rains yesterday may have washed off any fungicide residue, so recovering may be necessary. I have not seen any symptoms of sooty blotch and fly speck diseases. Blister spot in Crispin (Mutsu) continues to show up at more farms.

Pears continue to size well, with most being around 2.375 inches.

Tart cherry leaf drop from cherry leaf spot is continuing, with many yellowing leaves dropping to the orchard floor. Michigan State University Extension advises growers to apply a post-harvest fungicide to control this disease.

Plum harvest of both Japanese and early maturing European varieties continues for the few growers with a crop this season.

Small fruits

Grapes are continuing to fill the clusters for Concord and Niagara varieties. A few grape berry moths are continuing to be caught in traps and I continue to see a few Japanese beetle adults.

Strawberry leaves continue to enlarge and fill out the rows. Most new fields have now filled out their row. Growers that had more than a few inches of rain yesterday need to monitor soil moisture closely to be sure fields drain as quickly as possible, as plants with submerged roots or waterlogged soils can develop black root rot disease very quickly in these conditions. Growers may need to do some hand trenching to drain wet spots in fields. Signs of black root rot can begin to show quickly, as plants will suddenly collapse at the first signs of any stress, such as heat or drought stress.

Raspberry harvest for fall-bearing varieties continues. As with strawberries, growers that had more than a few inches of rain yesterday need to monitor soil moisture closely to be sure fields drain as quickly as possible; here again plants with submerged roots or waterlogged soils can develop black root rot disease very quickly in these conditions. Growers may need to do some hand-trenching to drain wet spots in fields. Signs of black root rot begin to show slower than in strawberries, but plants will suddenly collapse.

Trap catch of spotted wing Drosophila (SWD) continues to rise at most farms in the last week. This means that control measures need to be taken now and continue through the end of harvest. Consult recommendations in the “Spotted Wing Drosophila Management Recommendations for Michigan Raspberry and Blackberry Growers guide at the MSU Spotted Wing Drosophila website for details. Japanese beetles continue to be found in low numbers.

Blueberry harvest continues across the region. No blueberry maggots have been caught in traps. It seems very late for this to take place. I am not sure why I have not seen any blueberry maggot trap catch yet this season, but it is expected soon. Trap catch of SWD continues at most blueberry farms in the last week. This means that control measures need to be taken now and continue through the end of harvest Consult recommendations in the “SWD Management Recommendations for Michigan Blueberry Growers guide at the MSU Spotted Wing Drosophila website for details. A few Japanese beetles continue to be found in blueberries.

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