Southeast Michigan fruit regional report – July 29, 2014

Summer apple harvest is underway with blueberry and raspberry harvest continuing across the region. Second generation codling moth and oriental fruit moth are flying.

Weather

A line of thunderstorms moved over the central part of the region late in the day on Sunday, July 27, bringing strong winds and, for a few growers, severe hail. Winds from this storm toppled some trellis systems in apples and grapes and caused some apples trees to snap at the graft union. The winds seemed to come from all directions, which appear to be most stressful on the graft union resulting in breakage on dwarf apples. Some sharp and raged hail was reported, but most reports were of smooth, round, marble-sized hail with a few farms reporting enough hail to cover the ground. I counted an average of 18 hail stings on many apples in the worse areas hit. Summer red raspberry and blueberry fruit was knocked to the ground from a combination of strong winds, driving rain and hail.

Precipitation totals are all over the board this past week, with most areas receiving around 0.5 inches. Some farms had 1.5 inches of rain in the Sunday storms. Soil moisture supplies have continued to dry at most farms, with only a few farms having adequate soil moisture. Many growers have been irrigating in the past week. Most growers have been surprised at how quickly soils have gone from too much to too little moisture.

East Michigan growing degree day (GDD) totals for March 1 to July 28, 2014

Location

GDD42

GDD45

GDD50

Commerce (Oakland)

2,121

1,809

1,335

Emmett (St Clair)

2,140

1,828

1,358

Flint (Genesee)

2,344

2,019

1,526

Lapeer (Lapeer)

2,162

1,849

1,383

Petersburg (Monroe)

2,308

1,987

1,503

Pigeon (Huron)

1,990

1,695

1,246

Romeo (Macomb)

2,251

1,932

1,446

Tree fruits

Apples have sized well this season. Apples in the Flint, Michigan area are mostly 2.25 to 2.5 inches. Harvest of Transparent and Lodi apples started last week for some and is ongoing for others. Harvest of Jersey Mac is expected next week. Summer pruning continues as terminal buds have set for the season.  According to Michigan State University Extension specialist Eric Hanson, leaf tissue samples for nutrient analysis can be taken now.

Trap catch numbers of codling moth and oriental fruit moth are both on the rise this week, later than in other parts of the state. Both are what I believe are the start of the second generation flight. Many apple growers are finding a few fruit infested with small codling moth larvae feeding tunnels or frass from the first generation. Some fall webworm webs are being found for the first time this week, mostly of the edges of apple blocks.

Apple maggot trap catch has been low at most farms this season, although southwest Michigan trap catch numbers have risen sharply in the last week. A few mite hotspots continue to be found in most blocks. I am finding three species of mites in these isolated hotspots in a few apple varieties: European red mites, two-spotted spider mites and apple rust mites. Lastly, I am seeing a few more woolly apple aphids on terminals and fruit in the past week. Green apple aphids continue to be seen in the last few weeks. Japanese beetles continue to be seen in generally low numbers in all fruit crops; it appears that we will not see high numbers of this pest this season.

Other than these pests, there has not been much insect pressure in apples in the last two weeks. Predators are generally abundant this season, feeding heavily on the late-appearing green apple aphids these last few weeks.

Blister spot in Crispin (Mutsu) is a new disease to report in apples this week. The fire blight strikes that were reported several weeks ago are now very visible in the last week. I have not seen any symptoms of sooty blotch and fly speck diseases.

Pears have not sized much in the past two weeks; most are 1.75 inches in diameter.

Peach growers are continuing to remove dead trees and pruning less severely winter-damaged trees.       

Sweet cherry pruning is continuing; generally, this post-harvest window is less invigorating than late winter or spring pruning. Trees that have filled their space can be modestly trimmed in the post-harvest to early August window with less risk of bacterial canker than the traditional delayed dormant pruning time. Cherry fruit fly trap catch continues in low numbers.

Tart cherry leaf drop from cherry leaf spot is continuing to be seen with a new set of yellowing leaves being found in most blocks in the last few days. It is early in the season for this leaf drop to begin. Growers need to apply a post-harvest fungicide to control this disease.

Plum size increased in the last week with European plums mostly 1.25 inches and Japanese varieties close to 1.75 inches. Most growers have very few plums this season. Harvest of some early maturing Japanese plum varieties would normally be taking place this week.

Small fruits

Grapes are continuing to fill the clusters for Concord and Niagara varieties, with a wide range of fruit development stages this season. Wine grape shoots continue to emerge from latent buds on the winter-damaged trunks. The shorter and weaker shots can be pruned off at this time. A few grape berry moths are continuing to be caught in traps. A few Japanese beetles and grape berry moths are being found in grapes.

Strawberry renovation is complete and leaf growth is starting to be seen at most farms. Many growers have seen much quicker regrowth of leaves this season.

Raspberry harvest continues for summer red raspberry varieties. Limited harvest of fall-bearing varieties continues on a few shorter interior canes, harvest of the earliest fall fruiting types is expected in the next week or so. Fall-bearing varieties are growing very well this season with very long canes at most farms; some are approaching 6 feet in length. This could make harvesting operations difficult at farms that do not trellis their berries.

There has been no catch reported of spotted wing Drosophila (SWD) in traps placed in fields, but trap catch is generally continuing in fence rows adjacent to raspberries. I believe that there is such an abundant crop of wild hosts available this season that the SWD are feeding on these other fruits. When these alternative food sources are gone, I expect SWD to quickly move into cultivated berry crops. Fruit will need to be protected when first trap catch occurs in traps in fields. 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 in both summer and fall raspberries.

Blueberry harvest continues across the region. Demand for pick-your-own blueberries has been very strong so far this season. No blueberry maggots have been caught in traps yet, but are expected soon. A few Japanese beetles continue to be found in blueberries. Spotted wing Drosophila infestations are a threat to blueberries as well as raspberries. See the raspberry section of this report for details on SWD trap catch and recommendations. Consult recommendations in the “SWD Management Recommendations for Michigan Blueberry Growers” guide at the MSU Spotted Wing Drosophila website for details.

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