The plants didn’t like it either!

Fall is finally here, and the air has been crisp and clear recently. Leaves are starting to change to beautiful hues of red and gold. The normally scenic drive I take to work each day is improving every day, creeping ever closer to that classic New England postcard of autumn foliage.

Fig. 1: A maple tree outside a house I pass on my way to work is heralding what will hopefully be a dry and temperate fall.

It has been so refreshing that one can almost forget the deluge of water the northeastern states have received this summer. Unsurprisingly, I’ve received several emails and calls recently about plants in distress. I figured a blog post would be a great opportunity to describe some of the common (and less common) symptoms associated with stress caused by excessive water.

First, many trees are dropping their leaves early (the invasive Norway Maple, Acer platanoides, has been illustrating this in particular). Many trees are also dropping their leaves without first changing colors as one would normally expect. This is a common and, in and of itself, harmless symptom associated with an extended period of water stress. The bark of some trees is even splitting after the cyclic swelling after frequent rains followed by full sun exposure and warm temperatures.

Reduce irrigation if present and monitor the plants closely in the spring to see if leaves flush out normally. If they do, there is likely no need for alarm.

Naturally, roots can be severely damaged by prolonged exposure to water. Diseases caused by root rot pathogens like Pythium, Phytophthora, and Fusarium species have been very common this year. Even when a tree appears healthy aboveground, root damage and disease can prove fatal to the tree and may cause it to topple unexpectedly (see fig. 2). Homeowners with large trees near their houses should be particularly careful to not provide too much water to their trees after the wet summer we’ve had here in Connecticut.

Fig. 2: A tree on Horsebarn Hill toppled after a heavy rainstorm. Note the small and damaged root ball at the base of the plant.

Trees are not the only plants that have been adversely affected by the excessive rain! Bushes, herbaceous annuals, and even water-loving grasses have been stressed. Not only have grasses been more susceptible to fungal diseases as well, but they are being damaged by the sun more quickly due to the more frequent mowing and general stress associated with the heavy rain.

Fig. 3 The grass at the UConn Avery Point campus looks mottled and sad after being cut. These symptoms appear more frequently when the grass is stressed!

Not sure if your plants are receiving too much water? Simply perform the “knuckle test”. Place your finger in the soil near the roots of the plant in question. If you can reach damp soil before your first knuckle (1 to 2 inches), do not water! Very few plants actually need to be watered every day, and most require less water as the weather starts to cool down. Even the most water-loving plants will let you know when they are thirsty. When their leaves start to droop and the soil feels dry to the touch, give them some water. Until then, let them enjoy the dry, crisp fall weather too.

Nick Goltz