Southeast Michigan fruit regional report – July 9, 2013

First apple maggot trap catch for the season and harvest continues for sweet and tart cherries and summer raspberries.

Weather

It seems like the rain just does not want to stop at most southeast Michigan fruit farms, with some fruit growers getting another 1 to 2 inches of rain in the last two days. Rainfall totals for the last week have been extremely variable across the region, ranging from 2 to 7 inches. This being said, I know of a few fruit farms that have only seen a few tenths of an inch of rain over the past two to three weeks. It is from this latter group of growers that I keep hearing of these slow moving thunderstorms that keep moving around them. Soil moisture supplies are more than adequate at most fruit farms.

Our season is running behind normal again in terms of growing degree day (GDD) totals, but is almost normal when I look at growth stags and the start of harvest of our fruit crops.

East Michigan growing degree day totals for March 1 to July 8

Location             

GDD42

GDD45

GDD50

Commerce (Oakland)

1665

1422

1053

Emmett (St Clair)

1655

1416

1051

Flint (Genesee)

1840

1588

1207

Lapeer (Lapeer)

1694

1453

1086

Petersburg (Monroe)

1839

1582

1189

Pigeon (Huron)

1595

1362

1009

Romeo (Macomb)

1616

1382

1022

Tree fruits

Apples have sized very quickly over the past week in areas that have received rain – most are approaching 2 inches in the Flint, Mich., area. June drop is now complete in all blocked checked yesterday (June 8). More and more apples continue to show up. Hand-thinning continues in apples, and a few growers are considering going back into some high value apple blocks that were thinned a few weeks ago to do some more touch up work if time permits.

I caught my first apple maggot for the season last Wednesday (July 3) and a second one at another farm on Thursday (July 4). More have been caught since then. All were caught on yellow sticky cards. Upon apple maggot adult emergence there is an eight to 10 day period before female flies begin to lay eggs. During this time, they are searching for nutritional sources needed to become sexually mature. After female flies complete this pre-oviposition period and have mated, they will seek out fruit for egglaying. So, now is not the time to start to control it.

Monitoring adult apple maggot flight is key to effective management of this pest. Adult activity can be monitored using yellow sticky boards with ammonium bait and red sphere traps covered with an adhesive and baited with synthetic fruit volatile. The yellow trap is most useful during the pre-oviposition period when newly emerged females are actively feeding. The red sphere trap mimics the ripening fruit that flies are attracted to during egglaying and is effective throughout the season. Traps should be placed on the south-facing side of trees in perimeter rows because most flies are expected to be immigrating from wild hosts outside the orchard. Optimally, traps should be checked twice weekly until the first fly is captured, then once a week thereafter to indicate the end of the flight.

Codling moth trap catches rose sharply mid-last week and early this week after having no trap catch for several weeks. Some traps had 10 to 25 moths per trap since checked the prior week. I believe this is the end of the first generation ‘B’ peak adult flight and not the start of the second generation adult flight. Let’s keep an eye on trap catches in the next week to see if this trap catch is sustained.

Obliquebanded leafroller larvae have been found in a few apple blocks. Potato leafhopper adults are being seen in most apple blocks, especially on younger trees. Green apple aphid populations have been controlled in most blocks. Apple rust mite bronzing has been seen at a few more farms. Wooly apple aphid populations continue to move from the tree trunks to the terminal branches. There continues to be high numbers of predators being seen this season.

I continue to see a few fresh fire blight shoot strikes at many farms in the past week or so, and am finding just a touch of leaf and fruit scab in most apple blocks. Many apple growers are frustrated to find this much scab. Twig infections of powdery mildew continue to be seen, mainly on susceptible varieties.

Pears are 1.375 inches at most farms where growers have a crop. All stages of pear psylla continue to be present. Growers need to remove suckers to help bring the population into check.

Peaches are 0.5 inches in size. Fruit, twigs, branches and trunks continue to ooze from bacterial spot infection. X-disease continues to be seen. Harvest of some of the earliest varieties is expected to begin in a week to 10 days.

Sweet cherry harvest is complete at some farms, mostly ones that had a short crop, and will continue at others for another week or so. Fruit size is improving at most farms. I am very surprised not to see more fruit cracking this season. Cherry fruit fly trap catches have risen sharply in the last week; most growers should be finished with harvest before they are a problem. A post-harvest application may be required to reduce populations for next year.

No spotted wing Drosophila have been trapped in any fruit crop in southeast Michigan this season. Brown rot is starting to be seen at most of the few farms hit with hail in the last three weeks. Cherry leaf spot disease symptoms are being seen in many blocks. Birds are continuing to feed in most sweet cherry blocks.

Tart cherry harvest is underway at most farms. Tart cherry fruit size continues to be a problem. Cherry leaf spot disease symptoms are being seen in most tart cherry blocks, with yellowing leaves dropping to the orchard floor. Brown rot is starting to be seen at most farms where hail was observed in the last three weeks. No spotted wing Drosophila have been trapped in any fruit crop in southeast Michigan this season.

Plums remain 1 inch in size for European types, and Japanese types have put on a swell of growth and are now mostly 1.25 inches in size. Japanese types are starting to color.

Small fruits

Strawberry harvest has wrapped up at all farms. It was a very short and disappointing season for most strawberry growers, mostly due to weather-related challenges. A combination of temperatures that were either too cold for ripening or too hot, and excessive rainfall toward the mid-season, resulted in poor berry quality. Demand for pick-your-own, ready picked and wholesale strawberries was overwhelming this season and outpaced supply for most growers.

Growers need to get started with renovation. However, where fields are wet, growers need to delay beginning the renovation process so as to not destroy or harm their soil structure. I want to refer strawberry growers to a good weed control at strawberry renovation article written by MSU’s Bernie Zandstra and published last year (2012) on the Michigan State University Extension website to review this topic.

Potato leafhopper feeding and leaf curling is being seen in most new plantings. Newly planted berries are runnering well.

Raspberry harvest continues for summer red and black raspberries. Canes of fall-bearing types are about 36 inches tall. Some farms have an abundance of lateral canes or “bud berries” this season that are beginning to bloom. These early berries are not a part of the main crop. We see this phenomenon more some years than others.

Growers need to keep an eye for early spotted wing Drosophila infestations on these early bud berries. Japanese beetles are just starting to be seen in low numbers in a few raspberry fields. Leaf curling from potato leafhoppers is being seen in both new and established raspberry plantings. No spotted wing Drosophila have been trapped in any fruit crop in southeast Michigan this season.

Blueberries are starting to color with harvest expected to begin in the next few days on early maturing varieties. Most of the main season varieties are just now starting to color. No blueberry maggots or spotted wing Drosophila have caught in traps this season.

Grape cane growth continues at a rapid pace. Concord types are at berry touch and French hybrid types are at marble size fruit. Japanese beetles are just starting to be seen in low numbers in a few grape plantings. Grape berry moths have been caught in traps in commercial plantings in the last two weeks.

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