By Joe Zeleznik, Forester

NDSU Extension

My friend Karen teaches college-prep math at our local high school. As a gift for her graduates this year, she bought them water bottles with printing that read, “English is important. Math is importanter.”

I laughed my head off.

Of course, she’s just poking a little fun at her colleagues in the language arts, while emphasizing her own field of expertise. But the wording raises a challenge I face every day: how do we communicate what’s “normal” in nature?

The meteorologists discuss this all the time. “Normal” and “average” are two very different things. Usually, only a deep discussion of statistics actually clears this up for me. As I understand it, “normal” includes all the variability we see every year. It includes the extremes, whether they’re high or low, even when those extremes don’t occur very often.

Here’s an example. I once was asked, “Is it true that trees produce one single growth ring each year?” I replied that, in this part of the world, yes, it’s mostly true.

Did you catch how much I waffled?

“In this part of the world.” In temperate climates, not tropical climates, trees generally do put on one growth ring per year. During extremely dry years, conifers might not add a ring at the bottom of the tree. But that ring might be fully formed at the top of the tree.

The waffling: “might.” The qualifier: “top, but not bottom.”

Is a missing ring on conifers “normal”? During an extremely dry year, yes, it is. Is a missing ring on conifers “average”? Not at all. It’s not common.

Let’s look at another example. Late last summer, lilacs were blooming across the state. It was weird, and a lot of people were worried. Would their shrubs survive the winter? Was this part of a long-term decline? Was there a new disease or insect pest of lilacs?

Nobody asked, “Is this normal?”

And I understand that. Lilacs don’t usually bloom in fall! They bloom in the spring and early summer. Even “late lilac,” also called Villosa lilac, should be done blooming by the end of June.

In 2025, across much of the state, late spring and early summer were pretty wet. Conditions were perfect for fungal diseases of tree and shrub leaves. Lilacs throughout the region lost much of their foliage, and the shrubs went into a type of dormancy early.

The lilacs set their flower buds, but once growth conditions improved in the fall, with cooler temperatures, the lilacs blossomed. And while the timing of flowering was uncommon, the whole process was normal.

The same situation occurred with lilacs in 2024 in eastern North Dakota. Wet conditions caused leaf damage, which shut down plant growth. Flower buds set but opened up in the fall.

Normal? Yes. The disease that causes this issue is called Pseudocercospora, and it’s widespread. It does infect some lilac leaves every year. Usually, though, it’s not to the point that the trees go dormant.

So, was this situation “normal”? Yes. Was it average? Absolutely not.

Nature is pretty variable. From one location to another, from one year to the next, weather conditions are different. And how they affect plants, and the pests that harm them, can be incredibly variable.

And communicating that variability is pretty challenging. I wonder if the meteorologists will tell me I got it wrong.

NDSU Agriculture Communication – June 9, 2026

Source: Joe Zeleznik, 701-231-8143, joseph.zeleznik@ndsu.edu

Editor: Dominic Erickson, 701-231-5546, dominic.erickson@ndsu.edu