Southeast Michigan fruit update – April 11, 2023
Print
EmailEmergence from dormancy in a wet spring.
Welcome to the second in-season fruit article update for southeast Michigan for the 2023 season. Throughout the season, these updates will include information about the weather in the past week and the upcoming week, a fruit-by-fruit guide to current conditions with appropriate pest and disease updates, and other relevant observations.
General observations
After last week’s storm events we have seen fair, dry, and warm weather and those trends should continue through Friday.
This is likely the last week or so to get delayed dormant sprays on your crops. Once you see open unfurled leaves or half-inch green, you start to risk phytotoxic damage with sprays. This is also the time to finish the pruning on tender apple cultivars and stone fruits. Based on RimPro models, we are expecting the potential for apple scab infection over the weekend. The risk of economic loss due to scab is highest early in the season because it is a disease that will recur and intensify with successive generations. See the latest weekly fruit meetings for southern Michigan on MSU’s Kaltura Media Space (these may take a few days to upload after the Monday meetings).
The trap line monitoring has started at the Trevor Nichols Research Center in Fennville, MI. The season’s typical first emergent pest, the green fruitworm, is still the only pest that has been trapped there so far this year. Plans are being made for the southeast Michigan trap line to start later this spring. I have reached out to a few growers already, but I am still looking for a site with cherries (sweet or tart) somewhere north of Flint, MI, so please contact me if you have any.
Fruit-by-fruit conditions
Apples: Even though we are still behind our average degree day accumulation, 0.25-inch green has been reported in apples near our warmest Enviroweather station at Deerfield, MI. Further north in Novi, MI, we are mostly at green tip with a few later cultivars still in silver tip. In Fenton, MI, on Monday the apples were primarily at silver tip. Scab sprays should be applied at the next opportunity as we break dormancy. RimPro is currently reporting a risk of a scab infection event over the weekend. Powdery mildew season starts with half-inch green and rust season starts around pink, so it is wise to use scab-specific products for early sprays.
Blueberries: We have seen swollen buds in blueberry plantings in Fenton, but there is still time for lime sulfur dormant sprays. This is the primary risk period for mummy berry. Canes can be mulched in or burned.
Brambles: We are seeing some bud scale separation in raspberries in Washtenaw County as well as in southwest Michigan. There is still time for lime sulfur dormant sprays.
Cherries: Bud swelling to side green has been seen in Novi and Fenton. Copper sprays aren’t recommended past the pre-bloom stage because of phytotoxicity.
Grapes: No movement yet. Dormant sprays are still effective.
Strawberries: Some movement seen in southwest Michigan with new leaves emerging from crowns. Flowers can be killed by 10 degree Fahrenheit temperatures while still in the ground at 20 F temperatures once emerged. Early season fungicides should focus on controlling leaf spot.
Peaches and nectarines: Peach leaf curl can be kept under control with a fungicide application either in the late fall or just before bud swell, but not when leaves are present. Peaches in Fenton are at the swollen bud stage.
Pears: Pears in Novi are at the swollen bud stage. Some pear psylla has been spotted in west central Michigan.
Plums: European plums observed in Fenton are at the swollen bud stage. Prune out black knot and dispose of the knots by burning or removing from the orchard. Sanitation is an important step in managing this disease. The critical periods for most fungal control is for petal fall to late June, but for brown rot specifically the critical times are during bloom and later on at fruit coloring.
Insect conditions
Oriental fruit moth: It is time to think about mating disruption before emergence.
Pear psylla: Can be controlled early with a good coverage of dormant oil. Later on, control requires reducing vegetative flushes and hand-removing suckers.
Rosy apple aphid: Check for colonies in fruit clusters when we get to the pink stage. If necessary, use a pre-bloom insecticide for control.
San Jose scale: Early season dormant oil applications before they produce their waxy shell are an effective way to control the insect. The next opportunity to control them is during their crawler stage around the second cover in apples.
Seasonal weather update
After last week’s rain and storms we have experienced primarily fair weather and those warm and dry conditions should continue through Friday this week. The weekend will bring clouds and precipitation, even with the possibility of snow on Sunday. We are experiencing a wetter than average start to the year. Soil moisture is near normal to start the season after being dry through most of last year.
|
Degree Day Accumulation Mar. 1 - Apr. 10, 2023, Forecast from Apr. 10-Apr. 16, 2023; issued Apr. 10 |
|||||||||
|
Station (County) |
Degree Days Base 42 F Current |
Degree Days Base 42 F Average (5 Yr.) |
Degree Days Base 42 F Forecast |
Degree Days Base 45 F Current |
Degree Days Base 45 F Average (5 Yr.) |
Degree Days Base 45 F Forecast |
Degree Days Base 50 F Current |
Degree Days Base 50 F Average (5 Yr.) |
Degree Days Base 50 F Forecast |
|
Commerce (Oakland) |
71 |
104 |
208 |
43 |
75 |
161 |
19 |
41 |
106 |
|
Deerfield (Monroe) |
107 |
135 |
243 |
71 |
98 |
188 |
32 |
56 |
119 |
|
Emmett (St. Clair) |
59 |
93 |
194 |
35 |
68 |
151 |
14 |
39 |
99 |
|
Flint (Genesee) |
88 |
122 |
227 |
54 |
88 |
176 |
25 |
49 |
116 |
|
Freeland (Saginaw) |
59 |
88 |
193 |
35 |
62 |
151 |
16 |
34 |
101 |
|
Hudson (Lenawee) |
90 |
118 |
219 |
57 |
86 |
169 |
27 |
50 |
108 |
|
Lapeer (Lapeer) |
81 |
111 |
218 |
50 |
80 |
169 |
23 |
45 |
111 |
|
Pigeon (Huron) |
50 |
73 |
150 |
31 |
51 |
113 |
15 |
28 |
67 |
|
Romeo (Macomb) |
73 |
105 |
212 |
44 |
74 |
164 |
17 |
40 |
107 |
|
Average of stations in this region: |
75 |
105 |
207 |
47 |
76 |
160 |
21 |
42 |
104 |
In the short term, we can expect highs in the upper 70s through the end of the week. This should include relatively warm overnight lows, which will contribute to continued phenological progression in the field. These highs will cool back into the 40s and 50s over the weekend with lows dropping into the 40s or the 30s in more northern areas.
In the medium term, we are looking at both the mean temperatures and precipitation dropping back to normal and possibly below normal. The long lead outlooks are still calling for warmer and wetter than normal conditions for the late spring and summer seasons.
Our regional average growing degree day (GDD) accumulation for the season so far is behind the 5-year average by 30 GDD at 42 F, 29 GDD at 45 F and 21 GDD at 50 F (see table below). Degree days accumulate when average temperatures for the day exceed the base temperature of the model. So, even though we have seen a warm winter, the temperatures have consistently stayed below the those needed to gain many degree days. Read this Michigan State University Extension article to learn more about degree days: Understanding growing degree-days.
Watch Jeff Andresen's Biweekly Agricultural weather forecast reports.
More information and reports on normal weather conditions and departures from normal can be found on the NOAA Climate Prediction Center website, NOAA U.S. Climate Normals website, NOAA Climate Normals Quick Access Page (which may be searched by region), and Midwest Regional Climate Center website.
