Michigan’s fruit crop may be at risk if the occasional warmer weather persists. However, the upcoming colder temperatures could potentially save the crop.
When the average temperature for a day exceeds 42 degrees, fruit tree development can be observed. This increase in temperature prompts the trees to experience growth.
Nick Schweitzer, a fruit grower at Schweitzer Orchards in the Sparta area, is starting to feel anxious about the unusually warm weather we have been experiencing. Schweitzer Orchards, a long-standing family-run orchard, has been a part of Alpine Township since the 1850s. Today, it is operated by fourth and fifth-generation growers.
Schweitzer’s fruit trees are currently in the early stages of bud development, known as green tip. At this stage, the buds are fully formed and you can start to see the green vegetation peeking out from the tips. Fruit trees are quite resistant to cold temperatures until they reach the green tip stage. However, as the buds continue to develop into full flowers, they become more susceptible to colder temperatures.
According to MSU, they have a chart that illustrates the different stages of apple fruit buds and the level of cold each stage can withstand. It is interesting to note that as the bud development advances, higher temperatures actually cause more damage.
Michigan fruit growers, including Schweitzer, have a different perspective on the weather than most people. Instead of hoping for a warm spell, they actually desire a cooldown. This is because a drop in temperature would help to slow down the growth of fruit buds.
Fruit growers may find the upcoming chilly spell over the next few weeks to be a much-needed relief from their worries.
Fruit bud development can be monitored by measuring the accumulation of Growing Degree Days (GDDs). GDDs are calculated when the average temperature for a day reaches or exceeds 42 degrees Fahrenheit. Once a fruit tree reaches around 130 GDDs, it breaks its winter dormancy. Currently, in most of the fruit growing area of southwest Lower Michigan, we have accumulated 140 GDDs due to the recent pleasant spring temperatures. If the weather continues to be warmer than usual, it will further stimulate the development of fruit buds.
Fruit trees at the green tip stage can withstand temperatures in the teens without significant harm. Among fruit trees, apples exhibit the highest tolerance to cold, while peaches and apricots are more susceptible.
According to the chart provided, it can be observed that the apple blossom becomes susceptible to damage at a temperature of 24 degrees when the pink color of the blossom is just starting to appear. Additionally, a temperature of 25 degrees can lead to the death of 90% of the fruit blossoms on the tree once they have fully opened.
Fruit growers, unlike many of you, actually prefer daily temperatures to drop back to the 30s and 40s in order to halt bud development. In the next few days, as temperatures reach the 50s, bud development will slow down, but then cold weather is expected to arrive this Sunday. Throughout next week, overnight and early morning temperatures are likely to be in the 20s, while the afternoons will range from the 30s to 40s. This significant drop in temperature will effectively slow down fruit bud development. It is worth noting that the next critical stage, known as tight cluster, occurs at around 240 GDD’s. However, with the upcoming cold weather next week, this bud stage will be delayed until around April 1. It is important to remember that apple buds are vulnerable at 21 degrees during the tight cluster stage.
If warmer than normal weather returns in early April, there is a possibility of the freeze concern resurfacing. It would be devastating for Michigan’s fruit crop and growers if the temperature drops to 25 degrees as the fruit blossoms reach full expansion.
In 2012, Schweitzer vividly recalls a sudden shift in weather that wreaked havoc on his family’s orchard. It was March, and the temperatures soared into the 80s, causing the fruit trees to burst into full blossom much earlier than usual. However, the promising sight was short-lived. A cold morning in late April brought temperatures plunging into the low 20s, mercilessly snuffing out the hopes of a bountiful fruit harvest in Michigan. The devastating frost killed off most of the fruit, leaving Schweitzer’s family orchard with a meager yield of only 2,000 bushels of apples. This was a stark contrast to their usual harvest of 100,000 bushels.
Michigan’s various fruits have varying levels of tolerance to late season cold. For instance, blueberries typically blossom later in the season, which helps them avoid damage from freezing temperatures during April mornings.
