Weather stress is showing with early fall tree color
In recent years, it hasn’t been uncommon to see fall tree color begin at the end of October, but this year tree color and leaf drop started in some trees during the last week of August. The change isn’t due to cooler temperatures, it’s happening for a less pleasant reason.
“We are heading into that time of year where colors change,” said Steven Courtney, Manager of Hidden Lake Gardens “but my opinion is that the trees are stressed.”
Courtney explained the trees are stressed from not only the severe summer drought, but also the extremely warm temperatures through most of the summer. Michigan trees are not used to having repeated 100 degree days for an extended length of time. The exact same species of tree in Atlanta would not find the higher temperatures stressful because that is the norm in the southern part of the United States.
“One big rain doesn’t make up for three months of no rain,” Courtney said. “This long period of hot dry weather is very hard on trees. Even trees that were watered this year, they’re still fried, because they just could not handle the daytime heat stress.”
To cope with the weather-related stress, the tree begins to reduce its food supplies so it can survive the winter, according to Courtney. “Many of these trees have been through stress before and will be just fine,” he said.
Trees that are very young are most vulnerable to dying after experiencing stress. Courtney suggested that stressed trees in the landscape can be helped by applications of a balanced 12-12-12 granular turf fertilizer in the very late fall or early spring.
“You do not want to be fertilizing at this time of year,” said Courtney. The danger is that if the weather warms up for any period of time in the late fall, it would spark new growth in a fertilized tree and that new growth likely would not survive winter.
Heat stress is more noticeable in decidous trees as opposed to conifers. Courtney said, “Decidious trees don’t have the same water-saving abilities as the conifers.”
However there isn’t much advance notice when a conifer is stressed to the point of dying. “Conifers don’t tend to give you much warning,” said Courtney.
Because the trees have had a tough year during this growing season, there may be a lot of seed pods next spring. “They want to be able to continue their lineage, so if there is a stressful situation many times they will produce more seed the next year,” Courtney said.
For those considering adding trees to the landscape, fall is still a good time to plant deciduous trees. The key for a newly planted tree is lots of water. “They need to be as hydrated as possible to go into the winter,” said Courtney.
The method for watering is as important as the water itself. Courtney said, “I like a slow trickle. Put your hose trickling on the top of the root ball and let it run.”
For those with a heavy clay soil base, Courtney suggested the water should drip for about an hour. Those with a very sandy soil should let the water run for a longer time, trickling overnight is good if the water bill isn’t a consideration.
Weather stress has also had an impact on trees at Kapnick Orchard, according to co-owner Scott Robertello. Because of the early warm temperatures in the spring followed by freezing temperatures, there are smaller tree fruit crops this fall. The heat and drought damage from the summer are creating a different problem.
Robertello explained that fruit buds for the next year set in the summer. All the fruit buds were very much affected by the drought this summer, and may die in the winter or not have enough energy to develop good fruit next year.
Robertello said it isn’t clear right now how much damage has been done. This fall’s smaller crop will save the trees, because the focus of the tree is to reproduce itself in the fruit. Too much fruit on a stressed tree will kill the tree.
“It might be two or three years down the road before the fruit trees recover,” said Robertello. “The biggest concern is a smaller crop next year.”
For years Michigan was a perfect region to grow apples because the freezing of the Great Lakes in the winter meant a cooler spring with a slow and steady warm-up. These weather patterns are changing, and it is affecting the way Robertello looks at his crop.
“The extremes are more extreme every year,” he said. “There’s not a pattern, it just goes from one end of the spectrum to the other.”
One adjustment Kapnick Orchard plans to make is planting apple varieties with a later harvest. Pink Lady apples usually ripen in the middle of November, and now that the temperatures are warmer longer in the fall, it is an option for the orchard.