Southwest Michigan fruit update – Sept. 3, 2019

William Shane<shane@msu.edu>, Michael Reinke<reinkem3@msu.edu> and Mark Longstroth<$authorEmail>, Michigan State University Extension - September 04, 2019

Plum, pear and apple harvest is underway.

Bin full of apples — Apple harvest is beginning in southwest Michigan. This is a bin of just harvested Sweet Tango. Photo by Mark Longstroth, MSU Extension.

Weather

The last two weeks have seen a gradual cool down. Highs two weeks ago were near 80 degrees Fahrenheit with lows dropping from the 60s into the upper 40s. Last week saw highs generally in the 70s and lows in the 50s. The only significant rain in that period was a rainy day on Monday, Aug. 26. Labor Day weekend was cool and dry.

Rainfall totals for the last two week ranged from 0.3 to 2.3 inches. Rainfall totals for the season are 16 to 23 inches since April 1. The average is almost 20 inches. The potential evaporation for the season since March 1 is about 21 inches of water. The dry conditions in July and August have left many sandy soils dry, and these sites need irrigation.

We are seeing color change in the leaves of drought stressed and weak trees. Plants that lose their leaves early, such as five-leaf ivy, are also changing color. The forecast this week is for rain Tuesday and cooler temperatures with highs near 70 and lows around 50.

Southwest Michigan GDD summary from March 1 – Sept. 1, 2019
Station	GDD 42 F	GDD 45 F	GDD 50 F
Benton Harbor (SWMREC)	3267	2836	2175
Lawton	3300	2868	2200
Fennville (TNRC)	3061	2642	2004
Average for the SW region	3267	2835	2175

Check out the animated weather forecasts from Jeff Andresen at the weather tab in the Michigan State University Extension Fruit & Nuts Page. Articles and other regional reports can be found at the Fruit News page. There is no weather report this week.

Tree fruit

Trap catches for many late season moth pests remain high. Oriental fruit moth trap catches are still high in many orchards. The third generation could continue for several weeks. Obliquebanded leafroller trap catch is actually up in many orchards. Codling moth numbers are up or down depending on the orchard being trapped. A few brown marmorated stink bug adults are out. Brown marmorated stink bug can cause significant damage late in the season. Growers treating for other orchard pest will want to be sure they include materials that will also control brown marmorated stink bug.

Peach twigs with OFM damage — Without fruit in peaches, oriental fruit moth will attach the shoot tips where the larvae burrow into the shoot tip killing and deforming it. Photo by Mark Longstroth, MSU Extension.

Peaches are showing leaf discoloration and early fall color on trees with chronic winter damage and nitrogen deficiency. Gummy terminal branch tips due to oriental fruit moth entry are turning black. Phomopsis infection of these areas provide an overwintering site for this disease.

In cherries, post-harvest chlorothalonil applications help reduce late season cherry leaf spot buildup. Cherry leaves are always susceptible to leaf spot, but due to the dry conditions and post-harvest sprays most cherry orchards still have a good canopy of leaves, but a few orchards are nearly defoliated.

In plums, Stanley plum harvest is underway. Brown rot was a problem in some orchards this season. Knocking off rotted fruit before the fruit dry on the branches helps to reduce the carryover problem for next year.

In apples, Zestar harvest is underway. Macintosh harvest will start soon, as will Gala. Some growers are already picking these apples for the market and the harvest of processing apples is underway as well. Recent cool weather has improved fruit color. Sandy sites are showing effects of recent dry weather.

Estimated harvest dates for apples are approximately six to eight days later than normal and about eight days later than last year. Dry weather will increase tendency of apples to drop. ReTain applications for harvest management (stop drop), are generally recommended at 30 and 14 days before harvest. The Enviroweather apple maturity app can be used to estimate predicted harvest dates for your area.

Normal and predicted 2019 peak harvest dates for apple varieties in central Berrien County in southwest Michigan based on weather data at the Southwest Michigan Research and Extension Center, Benton Harbor, MI.
Variety	Normal date	2018 Predicted peak harvest date	2019 Predicted peak harvest date
Paula Red	Aug. 22	Aug. 20	Aug. 28
Zestar	Aug. 22	Aug. 20	Aug. 28
Gingergold	Aug. 20	Aug 18	Aug. 26
McIntosh	Sep. 10	Sep. 8	Sep. 16
Gala	Sep. 8	Sep. 6.	Sep. 14
Early Fuji	Sep. 3	Sep. 1	Sep. 10
Honeycrisp	Sep. 13	Sep. 13	Sep. 20
Empire	Sep. 19	Sep. 23	Sep. 26
Jonathan	Sep. 22	Sep. 24	Sep. 30
Jonagold	Sep. 22	Sep. 24	Sep. 30
Golden Delicious	Sep. 25	Sep. 27	Oct. 1
Red Delicious	Sep. 28	Oct. 1	Oct. 7
Ida Red	Oct. 5	Oct. 8	Oct. 15
Rome	Oct. 5	Oct. 8	Oct. 15
Fuji	Oct. 20	Oct. 22	Oct. 28
Braeburn	Oct. 20	Oct. 22	Oct. 28
Goldrush	Oct. 26	Oct. 28	Nov. 3

We will begin our apple maturity reports this week.

Bitter rot symptoms on apple fruit are showing up both on leaves and fruit. Codling moth, oriental fruit moth and obliquebanded leaf roller are all threats to fruit now. All three of these pests are flying and laying eggs. Apple maggot numbers are down but we are still catching this fly. This is a pest of sandy soils and it often emerges after a rain.

Small fruit

Concord late veraison — Concord is one of the few grape varieties unscathed by the frigid winter temperatures with a good crop in southwest Michigan. Concords are nearing the end of veraison but are not very sweet. Harvest is about a month away. Photo by Mark Longstroth, MSU Extension.

Spotted wing Drosophila (SWD) trap catches continue to be high. In some areas, trap counts are down as the number of fruit available has really declined. This pest’s population builds to very high numbers into the fall. It breeds on wild and commercial berries. It only takes 10 to 14 days for the fly to go from egg to egg laying adult. Growers and scouts should monitor for this pest in the field and the edges of the field and protect ripening fruit.

Grapes are finishing or past veraison for most varieties. We have heavy dews every morning and under these conditions downy mildew can spread quickly. Botrytis and sour bunch rot of the berry clusters are a concern (see “Late season cultural and chemical options for diseases in grapes—don’t wait!”)

Grape berry moth trap catches are declining in most vineyards but we are still trapping this pest and egg laying continues. See the MSU vineyard IPM scouting report for Aug. 28, 2019 for more information.

Blueberry harvest is winding down. Some growers are still harvesting late varieties such as Elliott and Aurora. The primary pest concern is controlling SWD. Growers should be protecting their fruit. Spray coverage needs to be maintained until harvest is finished.

new blueberry flower buds — Flower bud development in blueberries is at the tips of this year’s shoot growth. Flower buds enlarge and become noticeable in September. Photo by Mark Longstroth, MSU Extension.

Maintaining good plant water relations in this dry season is important. With the shorter days, plants are using less than 0.1 to 0,05 inches of water a day. Blueberry fields should be kept moist in September. Fruit bud development is starting and expanding buds are visible. Drought conditions can reduce next year’s crop potential by reducing flower bud numbers.

Strawberries are growing well. The fields need be irrigated to maintain good plant growth. Include fungicides to protect the leaves from foliar diseases. See Protect strawberries from foliar diseases after renovation for more information.

Fall raspberry harvest is underway. Raspberries and blackberries are very attractive to SWD and fruit needs to be protected from this pest. One effective way to reduce SWD is to shorten the harvest interval to two days and pick all ripe fruit. Sort out the soft berries and destroy them away from the field. In summer raspberries, old floricanes should be removed to increase sunlight and air flow in the planting reducing disease.

This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).