Dealing with invasive species

According to Sam Schultz, terrestrial invasive species coordinator with the state Department of Environmental Conservation’s Partnership for Regional Invasive Species Management (PRISM), one of the best ways to battle invasive species is with a hand tool called the hand grubber.

In her work in managing invasive species, she refers to it as a “best friend.” Schultz and Colleen Lutz, assistant biologist with the New York Natural Heritage Program, delivered a lecture on invasive species at the Copake Grange Saturday, March 2.

Lutz began the presentation with this definition: “Invasive species are non-native plants, animals and pathogens that cause harm to the environment, the economy or human health.”

She and Schultz discussed a few invasive plants and insects. Japanese barberry, Oriental Bittersweet, multiflora rose, tree of heaven, and autumn olive are all invasives present in New York state. They were introduced to the United States in the mid to late 1800s to use as a hardier substitute for native plants, as ornamental plants or, in the case of the multiflora rose, to use as root stock for ornamental roses and for stabilization of soil.

Invasive plants tend to “grow anywhere” and quickly, and “out-compete” native plants. Unfortunately, Lutz said, most of the invasive species like the “warmer, earlier spring weather” that climate change is causing and that they have “increased growth due to increased CO2.”

Schultz contributed that Oriental bittersweet is known as “forest killer” because its vines climb trees, and the weight pulls the tree down.

Lutz moved on to invasive insects and talked about the hemlock woolly adelgid, spotted lanternfly, jumping worm and emerald ash borer.

The hemlock woolly adelgid is “like an aphid,” said Lutz. “It sucks into the needle of hemlock trees and sucks the nutrients out and makes the hemlock weaker and more susceptible to disease.”

Spotted lanternflies were first seen in Pennsylvania in 2014. They are known for eating crops, particularly grapes, and “love the tree of heaven,” another invader.

Lutz moved on to the jumping worm. They “excrete coffee ground-looking” castings and “jump around and act crazy.” Jumping worms deplete soil of nutrients, which kills plants. They can be identified by a milky white band and their erratic behavior.

They are spread through compost and plants from nurseries. Lutz and Schultz suggest checking compost brought to a property for these worms before spreading it and also heating it by putting black plastic over it and letting it reach a temperature of 104. This would kill the eggs, which are too small to be seen.

She also said to check and rinse all plants brought in down to the roots and to throw away the dirt: “Wash boots off with a hose so that eggs clinging to them are not spread to other properties.”

Of the spongy moth, Lutz said, “They will go after 300 species of trees, but have 150 primary host species that they prefer to eat,” oaks being the most favored.

Lutz explained how the Heritage Program classifies invasive species with a tier system, with Tier One aimed at prevention of invasives, Tier Two aims at eradication. At Tier Three, the aim is to contain the invasive and at Tier Four, it is here to stay, and the focus turns to long-term management.

This system allows program biologists to “decide which species are here and not here and how impactful it is.” They then share their information with the PRISM so that a plan can be made to manage invasive species.

Oriental bittersweet, Japanese barberry, tree of heaven, multiflora rose, and autumn olive are all Tier Four. Also in Tier Four are the emerald ash borer, hemlock woolly adelgid, spongy moth and jumping worm.

Schultz began her part of the presentation by describing methods to combat the invaders. She explained Integrated Pest Management (IPM), which uses an “adaptive ecosystem- based approach exploring multiple control options targeting invasive species.”

The methods used, she explained, come “from a range of manual, mechanical, cultural and biological control methods with the goal to maximize effective control and minimize negative environmental, economic and social impacts.”

She listed mechanical methods as “hand-pulling, grubbing, girdling, grazing, hoeing, mowing and/or excavating.”

At this point, she introduced, with a flourish, a hand tool which she called a “best friend”: the hand grubber. She extolled its virtue of getting roots out.

Cultural controls “are practices that reduce pest establishment, reproduction, dispersal and survival, and limit exposed soil with restoration.” This is as simple as tamping soil down so seeds can’t easily grow and monitoring for regrowth. She recommended planting native species in places where invasive species have been removed so that any seeds left can’t take hold.

Biological controls involve realizing and encouraging natural “predators, parasites, pathogens and competitors to feed on or disrupt an invasive species.” Schultz assured the audience that these “predator species were researched for 10 or more years so they know they won’t hurt the environment.”

She gave the example of the release of the silver fly, which feeds on the woolly adelgid. The silver fly, however, has had problems thriving in the cold winters in New York.

Chemical control, Schultz said, is a last resort and must be used carefully while following label instructions. She suggested using a small paintbrush to apply the herbicide to the cut stem or stump of invaders. The herbicide is absorbed by the plant and kills it.

Schultz said control plans are prioritized. It is best, she said, to “start with low-density satellite populations” and then go “into the core of the infestation.” She said this prevents the satellite infestations from spreading seeds and becoming more populous.

She said it is important to implement any of the strategies that are “most effective before seed” and it is important to “attack the root ball and deal with the seed bank” when using the digging-and-pulling strategy.

The mowing, cutting and grazing methods will weaken the root systems and cause them to die out. They must be done repeatedly and must be done before the plants go to seed.

Another method is to cover the plant with a “contractor’s black trash bag,” which will kill it and its roots. “Make sure none creeps out,” she said.

Invasive trees can be girdled all the way around, exposing the inside to disease and pests, which will eventually weaken and kill them. They can also be drilled or cut, and herbicide placed inside to kill them or painted on the girdled bare space.

For the hemlock woolly adelgid and the ash borer, a tree can get a basal bark application. The bark at the base of the tree is sprayed all around the base and the spray is then taken up by the tree and goes up into it and keeps the insects away for a year or two. With spongy moths, Schultz suggested using burlap to wrap around trees, particularly the oaks that they favor, to discourage the larvae from climbing into trees and eating foliage.

She said to dispose of invasive plants after pulling or cutting by “solarizing” them, which means to bag them and put them in the sun for two weeks. For woody plants, she recommends mulching, chipping or burning if allowed. She said that “non-fruit-bearing trees can be propped against or suspended” with “their roots exposed to decompose or arranged into brush piles for wildlife habitat.” If chemicals are used, plants should not be touched for two weeks.

Schultz and Lutz concluded by saying people could help with invasive species by joining the iMapInvasives network at www.imapinvasives.org to report any that they find, and go online to New York Natural Heritage Program at nynhp.org or Capital Region PRISM at capitalregionprism.org for more information.