This article is a follow up to Carl Mansfield, tree consultant for MLF farm visit on September 7, 2019.  On June 22, 2020,  Deb Pella Keen, Executive Director, MLF visited the MLF farm with Ken Jewett, founder of MLF.   We again observed the Lymantria dispar dispar or LDD moth (also known as European Gypsy Moth) larvae feeding on several trees, and one unusual host tree, a larch. Digging in the internet we found some interesting information on LDD moths.  There are now two known species of LD moth invaders in North America: the LDD moth introduced to Canada over 130 years ago and now the Lymantria dispar asiatica / LDA (aka Asian Gypsy Moth) which while not known to be established in Canada, was first recorded in 1991 in North American at the port in Vancouver, BC according to the US Department of Agriculture (see PDF).

Although in many ways similar to the LDD, the discovery of the LDA moth in Canada has raised new concerns. According to Health Canada, the LDA prefers coniferous trees, is better adapted to colder climates, and the female is able to fly longer distances. These traits make the LDA moth a serious threat to Canadian forests.

The spread of the LDD moth has been largely attributed to the movement of firewood, as well as outdoor recreational and household articles.  Knowing how to detect, report and manage LDD moth could significantly reduce and limit the spread of LDD moths to new areas.  So if you find LDD moth larvae (caterpillars) this summer, do your part for citizen science and download this app (EDDMapS Ontario) and report your finding. 

EDDMapS is a web-based mapping system for documenting invasive species and pest distribution. It was developed by the Center for Invasive Species and Ecosystem Health at the University of Georgia, and since its launch in 2005 has now expanded to include the entire US and Canada. As of June 2020, EDDMapS had over 4.9 million records.

We did our part in reporting our finding of LD moth larvae at the MLF farm and while it is highly unlikely (we certainly hope!) that the moth we found was an LDA, it is important that we all learn more about these destructive invasive species.

For more information on LD moths in Canada and how you can control and prevent their spread see these links:

• forestinvasives.ca/Meet-the-Species/Insects/European-Gypsy-Moth
• www.canada.ca/en/health-canada/services/pest-control-tips/gypsy-moths.html

In the later fall and winter, when other food sources are scarce, voles, mice and rabbits eat the bark and underlying tissue of young trees. Voles frequently girdle a tree by removing a continuous strip of bark and cambium around the circumference of the tree, usually within 30 cm of the base of the tree. Trees do not recover from this girdling and usually die during the following year.

Some commercially available repellents used by fruit growers can effectively  discourage voles, rabbits and deer from feeding on trees. SKOOT and other brand name repellents contain Thiram, a distasteful but harmless fungicide that discourages animals from taking a second bite. With a paint-like consistency, the repellent can be painted onto the tree’s bark from below the original soil line to a height of 150-175 cm to discourage deer browsing, and feeding by rabbits and voles.

Before applying the fungicide, the bark mulch and a few centimetres of soil is removed from the base of the tree to allow the property manager to paint the trunk of the tree from below soil level to a height of 150-175 cm with the repellent to discourage feeding by voles, rabbits and deer.

Ensure complete coverage when applying the repellent and follow the  package directions.

Where there is a known threat of vole and rabbit damage, a galvanized hardware cloth cylinder with a 6-8 mm square mesh can be set in place around the base of the tree and buried to a depth of 5 cm into the soil.

The soil and mulch is then returned to its original form and depth, covering a few cm of the painted trunk at the base of the tree before three 15-20 cm wire staples are used to fix the cylinder in place, centrally around the trunk of the tree. Short pieces of poly-coated wire secure the cylinder to a 125 cm stake, driven at least 25 cm into the soil.

Individual Tree Wraps and Tree Guards may be more effective where vole and rabbit damage is concerned, in areas where there is a low deer population and minimal risk deer browsing.

Rabbits and voles gnaw the bark of young trees, consuming the outer and inner bark, exposing the inner wood. If the chewing extends more than half way around the trunk, the tree may not survive.

Protect the tree by wrapping a soft, flexible plastic tree wrap around the trunk. Starting at the bottom, bury at least 5 cm of the wrap below soil line and work your way upward. Be sure to wrap beyond the typical snow line. Remove the wrap in the spring.

In areas where deer may be a problem from browsing or rubbing their antlers against the tree trunk, use a tree guard 100-125 cm in length.

Tree guards also offer some protection from winter sunscald

Many different tree wraps and protectors are available from garden centers and farm supply outlets. A flexible plastic tree wrap is shown above on the left. A ventilated, corrugated tree guard is shown on its right.  We used both of these tree protectors to protect the native maples that were planted recently. Both installations include the use of a hardware cloth cylinder supported by a sturdy stake.

More information available at:

Protecting Trees from Animal Damage: http://www.agr.gc.ca/eng/science-and-innovation/agricultural-practices/agroforestry/diseases-and-pests/protecting-trees-from-animal-damage/?id=1198877618448

Newly planted trees (those planted within the past three years) require regular watering and care throughout the annual growing season. The first few years are the most critical to their long term survival and growth.

A 200-250 cm sugar maple sapling that was planted as a bare root tree in mid-May 2018. Note the hardwood mulch placed around the base of tree and the tree-watering bag set in place. The bag capacity is 65-70L when full with a draining time of  6-8 hours, but the bag content can be reduced when used for watering smaller sized trees.

Deep watering to a depth of 30-40 cm keeps the tree’s root zone moist (but not wet) and encourages rapid root regeneration that is essential to the tree’s reestablishment in its new environment.

MLF’s woodlot manager, Mike Fisher has been watering the 200-250 cm sugar maple saplings regularly, partially filling the tree-watering-bags with  40-45 L of water weekly. The trees were watered more frequently during the hot dry weather we experienced in June and July. The water soaks into the soil over a period of 4-6 hours, saturating the tree’s root zone.

It’s a year later and the sapling has grown to 20-25 mm stem caliper. The tree-watering-bag is in place, wrapped around the base of the tree and partially filled with water (40-45 L).

Note: This particular tree was planted in a more exposed location and required a stake to keep it upright while it grew new roots to support the tree. The stake will be removed in spring 2020 if the tree is well “anchored”.

On well-drained soils, 40-45 L per 25 mm of stem diameter/week should be enough water. Don’t overfill the bag as too much water can damage the roots by keeping the soil too wet. Water the trees every 4-5 days during hot, dry, drought-like conditions. 

Above: You can also use a DIY tree-watering-bucket,  an economical alternative to the commercial tree-watering-bag that is shown in the background. Capacity of 20 L. Fill twice to provide the 40-45 L required for each watering. Alter the location of the bucket placement relative to the tree trunk by 90 degrees as you water the sapling during the growing season, to encourage uniform root development around the tree. The duct tape flap covers the “fill hole”, preventing small birds from entering the bucket to get a drink.

The consequences of failing to adequately water recently planted maples – drought stressed leaves as the tree slowly dies.

Year four and after:  you can relax a bit on tree watering in later years but be prepared to water during long periods of drought.