Tree planting emerges from COVID into hot, dry spring

Additional threat of gypsy moth has foresters on edge as tree planting booms

Gypsy moths can defoliate trees if in large enough numbers.

Administrators of many tree-planting efforts across Ontario are striving in 2021 to make up for ground lost during the early days of the COVID-19 pandemic in 2020.

However, they now face a perfect storm of dry weather and widespread gypsy moth infestations.

Why it matters: Tree-planting for such purposes as windbreaks, shelterbelts and buffer strips are recognized agricultural best management practices for soil and water quality as well as species-at-risk protection.

“Survival (of newly-planted seedlings), I can almost guarantee, is going to be terrible,” said Upper Thames River Conservation Authority (UTRCA) Forester John Enright, the day before the conservation authority’s final planned 2021 planting on May 28 at the Southern Ontario Butternut Seed Orchard near Innerkip.

UTRCA crews typically plant tens of thousands of trees each spring, with additional seedlings and larger-stock trees picked up from the conservation authority and planted by landowners themselves. This year was the highest ever and trees sold out. 

The reason was twofold. Many of those trees replaced those that didn’t get planted in 2020 thanks to COVID-19 work slowdowns at supplying nurseries, conservation authorities and other planting agencies.

The UTRCA trees program gets support from Forests Ontario and Ontario Power Generation and funding allocated through its Clean Water Program.

“We had to defer a lot of projects,” said Hayley Murray, forestry operations co-ordinator for Forests Ontario. But this spring, with safety protocols — including personal protective equipment for workers, regularly sanitizing equipment and tools, minimizing planter density and staggered start times — there was full return to planting. Forests Ontario Forests Ontario aimed to oversee the planting of approximately 2.8 million trees across the province through a variety of partners including conservation authorities.

Secondly, as with many other do-it-yourself outdoor pursuits during the pandemic, planting trees rose sharply in popularity since March 2020. 

“We saw the demand for trees start to increase (last spring) with landowners contacting us at the last minute to see if we had any surplus trees available,” Enright said in a post on the UTRCA website. “That demand has continued to this day. I believe it is definitely COVID-related. More people are at home, with more time on their hands, looking to improve their properties by planting trees.”

At the nurseries, pandemic-related labour issues weren’t as severe as in 2020 but they did persist this year to some degree — enough to hamper efforts to keep up with the record-breaking demand. “Not only were we sold out but our supplying nurseries were sold out as well. This demand for trees is province-wide,” Enright wrote.

So once again this year, some landowners and planting partners were left deferring their plans until next year.

It’s possible, though, that deferring might end up being the best option. That’s because dry — and intermittently unseasonably hot — weather during the 2021 planting season left foresters fearing the worst for the newly transplanted trees. 

Enright’s family has a farm near Peterborough so he is well aware the dry, hot conditions persisted across southern Ontario.

“When we get a year with a drought in July or August, if the trees went into the ground in good shape, hopefully, they can establish some good roots to get them through,” he said. “But we don’t often get this kind of dry weather this early.”

According to Murray, this year’s planting season “started out well, when we were getting rain and cool weather.” But temperatures rose and rains disappeared far too soon across the province, and now she agrees the newly-planted trees face “a perfect storm.”

And the other major front of that storm is the gypsy moth. “Last year was a bad year (for gypsy moth) and it looks like this year is going to be as bad or worse.”

According to Enright, the most common hosts for gypsy moth infestations are red oak, sugar maple, poplar, birch and willow. Adult moths lay eggs on the bark and caterpillars emerge in May and climb into the foliage to devour the leaves. The caterpillars begin pupating in mid-June or early July, and emerge as adult moths in August — so the cycle can begin again.

“But when the population is this high, they’ll eat pretty well anything.”

Severe infestations have been noted, Enright says, from the southwest through to eastern Ontario, and north into the Muskokas.

The UTRCA forester takes some comfort in hoping the current gypsy moth explosion follows the four-year cycle observed with previous infestations. Last year, when landowners in certain parts of southern Ontario saw serious and widespread defoliation, was the third year. This year it’s quite possible that a naturally occurring fungus will cause a significant decline in gypsy moth numbers before the end of summer 2021.

A cool, wet spring might have hastened the arrival of that fungus, Enright explains. As it stands, though, “there’s going to be a lot of damage before we see that collapse — if it happens.”

According to Murray, if a healthy mature woodlot gets severely defoliated by gypsy moth caterpillars, it can usually recover. But it can also be temporarily at higher risk of longer-term damage due to additional stressors such as drought or an ice storm.

As for newly planted seedlings, they’re at less risk of infestation because they don’t host eggs. But given the stress of hot and dry transplanting conditions, there’s still reason to worry.

“I had one (participating) landowner who had watered 2,200 seedlings twice since we planted them,” he said. “And now he sent me a picture of gypsy moth (caterpillars) eating the leaves.”

About the author


Stew Slater

Stew Slater operates a small dairy farm on 150 acres near St. Marys, Ont., and has been writing about rural and agricultural issues since 1999.



Stories from our other publications