Southwest Michigan fruit update – March 28, 2023
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EmailThis is the first fruit scouting report of the season.
Winter
The winter of 2022-2023 was warm. Temperatures seldom dropped below 10 degrees Fahrenheit. An early cold event on Dec. 23-24 saw low temperatures close to 0 F for much of the region. Low temperatures from near freezing to the mid-teens for the month before acclimated the fruit crops before this event. No significant damage was reported in the region. Another cold event on Jan. 31 – Feb. 1 resulted in temperatures around 5 F. At that time, the most tender fruit crops grown in the region would have required temperatures below zero to see measurable cold damage.
Winter precipitation was near to slightly above average. Much of this precipitation came as rain. Early ornamental plants started showing signs of movement in late February and early March. Some fruit crop buds are just starting to swell now.
Below are the growing degree days (GDD) for the Southwest Michigan Research and Extension Center (SWMREC) near Benton Harbor, Michigan, for the last 15 years. Compare the 2023 numbers to the average for the last 15 years and you can see that we are below average. Note, 2012 was an extremely warm winter and has affected the long-term average. We are closer, but still behind average when the bias of 2012 has been removed.
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.
|
Year |
Base 42 F |
Base 45 F |
Base 50 F |
|
Average |
107 |
75 |
40 |
|
Average: without 2012 |
88 |
58 |
27 |
|
2023 |
52 |
25 |
5 |
|
2022 |
109 |
74 |
36 |
|
2021 |
137 |
101 |
57 |
|
2020 |
88 |
55 |
19 |
|
2019 |
49 |
28 |
10 |
|
2018 |
78 |
49 |
18 |
|
2017 |
226 |
161 |
85 |
|
2016 |
163 |
115 |
60 |
|
2015 |
37 |
24 |
12 |
|
2014 |
13 |
5 |
0 |
|
2013 |
41 |
25 |
8 |
|
2012 |
392 |
324 |
228 |
|
2011 |
51 |
31 |
14 |
|
2010 |
88 |
55 |
21 |
|
2009 |
138 |
98 |
48 |
|
2008 |
53 |
35 |
16 |
March weather
Temperatures have been steady for most of March. Much of the region has seen high temperatures in the upper 30s to upper 40s for most of the month, and low temperatures near freezing. At this time, most fruit crops would need to see temperatures near zero for significant damage. Comparing the degree day table for March below to the numbers from the table above, the majority of the degree days accumulated so far this year were from the warm January and February.
|
Southwest Michigan GDD summary from March 1 through March 26, 2023 |
|||
|
Station |
GDD 42 F |
GDD 45 F |
GDD 50 F |
|
Benton Harbor (SWMREC) |
20 |
8 |
1 |
|
Lawton (Lawton) |
19 |
7 |
1 |
|
Fennville (TNRC) |
15 |
5 |
1 |
|
Average for the SW region |
21 |
8 |
1 |
The forecast for the upcoming week is for lows near freezing and highs in the 40s. The one exception is Friday when a quick moving low-pressure system will bring some warm, wet weather for the day with highs near 60 and up to an inch of rain. Slight chances of scattered rain/snow mix are forecast for Wednesday through the weekend as well.
The medium range forecast for the first half of April is for cooler than average temperatures and higher than average chances of rain. Longer range forecasts fare for average temperatures and precipitation the rest of April.
Tree fruit
The past winter was relatively mild, with the only somewhat significant dips on Dec. 23 and 24, down to -1 F in the southeast part of the region. Tree fruit crop prospects are still excellent. Cool temperatures in March have slowed development. In general, temperatures in the teens now would likely cause some damage.
Dry conditions for the last month allowed growers to make good progress pruning. Check blocks for evidence of San Jose scale on branches to determine the need for oil sprays.
Apricots fruit buds are swollen with tips slightly separated.
Peach and nectarine fruit buds are showing signs of swelling with the tips light gray. If not already done, peach and nectarine should be protected against peach leaf curl infections. Infections require 10-plus hours of wetting with temperatures in the range of 46 to 55 F. Treatment now can help suppress additional infections when these weather conditions occur even past bud swell. Low levels of copper also suppress bacterial spot populations.
In cherries, no movement has been seen in the cooler areas of this region. Copper sprays can be safely applied to cherries. Copper applications may reduce bacterial canker in cherries.
In plums, Japanese plum fruit buds are visibly swollen with green tips on some, with European plum lagging behind. 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.
Apple early varieties Zestar, Macintosh and Jonathan are at silver tip in Berrien County. Green tip on early varieties like Macs and Zestar is expected approximately 110 degree days base 42 from Jan. 1. The degree-day 42 summary on March 27 was approximately 74 for the south to 44 at the more northern Fennville Enviroweather station. Rough guess for first green tip for early varieties under continued cool temperatures is around April 6 for the southern end of the region. Scab sprays will be needed to protect against future rains as green tissue emerges. Copper sprays can provide early scab control and fire blight suppression. Protectants are preferred over systemic fungicides at this time of year for scab control.
Pear buds are slightly swollen. Bud scales are starting to separate.
Small fruit
Grapes show no movement.
Blueberry growers still have time to apply copper, Sulforix or lime sulfur products to suppress early season diseases.
Strawberries have greened up and new leaves are starting to emerge from the crown. Overwintering mulches should be removed and raked between the rows. Some growers are putting out floating row covers. Growers are looking at early season herbicides to control overwintering weeds. When selecting an herbicide, check the pre-harvest interval (PHI). We are getting to the part of spring where some herbicide PHIs are cutting it close to predicted harvest dates.
Many bramble growers are dormant pruning. In summer bearing raspberries, last year’s primocanes should be headed (cut back) to the desired height and any remaining floricanes from last year should be removed. Fall bearing raspberries should be cut or mowed to the ground. Lime sulfur treatments for anthracnose can still be applied.
Upcoming meetings
Our regular southwest Monday fruit IPM updates will once again be a hybrid format. The meetings will be held in-person with virtual attending also available online. Our first meeting is Monday, April 10, at 5:30 p.m. You need to register to receive the Zoom link and password for these meetings. The webinars are free and one pesticide applicator credit is available for each meeting. The same Zoom link will be used with all the Monday meetings—you only need to register once.
Join the MSU Extension blueberry team the morning of April 5 for our first spring blueberry webinar! Sign up here.
This work is supported by the Crop Protection and Pest Management Program [grant no 2021-70006-35450] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.
