Environmentally Friendly Pest Reduction

November-December 2006

I DON'T KNOW ABOUT YOU but I’m feeling a little ripped off about the autumn this year. It seems like most weekends came with showers, cloudy skies and cooler temperatures. And as for that gorgeous Thanksgiving weekend, I missed most of it as I was nursing a very bad cold.

Autumn is by far my most favourite month, its bliss for the eyes and the nose and the lack of biting insects can lead to carefree adventures in the woods. Although the cool, wet weather hasn’t done much for retail sales of ornamentals (or my personal enjoyment), its been great to ensure transplant success and establishment of new specimens in the landscape. October and November are major root growth periods. Yes, 2006 was an excellent growing season. Although we had our share of heat and humidity, we seemed to get timely rains which almost eliminated the need for supplemental irrigation. If you take a good look at nursery stock this fall, you will see full foliage, excellent colour and a plethora of white, fibrous roots that are growing like gangbusters.

Of course, the “timely rains” did give us a little more than our fair share of diseases. And in late spring, we seemed to be battling a large onslaught of insects and mites. As maintenance activities and installations projects are finishing up, you may want to review some of your pest management practices and programs and plan for 2007. What worked? What didn’t?

As many service providers move towards more environmentally friendly means of pest management and general plant health care, consider some of the alternatives that exist in Canada and ask your colleagues about their experiences with these products.

I’ll always remember how one landscape professional was using repetitive insecticidal applications for magnolia scale and having poor results until he tried a fall and spring application of dormant oil. Since then I have heard many professionals talk about the merits of this product and how successful it has been for scale insect management in the urban landscape. Here’s a review of some of the products that have no (or low) toxicity to us but can be very effective against pests when used according label directions.

Horticultural Oils
This is a highly effective, non-toxic product. The effectiveness can be enhanced greatly with its proper use. Rule #1. It has to come in contact with the insect’s body or egg. It works by smothering the spiracles (breathing holes on the abdomen) so it can’t breathe. This means getting right in there, spraying the undersides of foliage and stems (where most insects like to hide and feed). Target pests include spider mites and other open-feeding mites, scale crawlers and nymphs, adelgids, some young caterpillars (e.g. leafrollers) and their eggs. Landscape Oil now includes many summer uses on the label, which extend the usefulness of this great product.

Insecticidal Soap
These are salts of fatty acids that kill insects by disrupting the organization of their outer membranes. So it works well on soft-bodied insects like aphids, mites, adelgids, scale crawlers and young caterpillars. The soapiness of the mixture can be greatly depleted by the alkalinity of the water it is applied in. If a few drops of insecticidal soap in a half litre of water don’t make a nice sudsy mixture when shaken, the water isn’t suitable for carrying insecticidal soap and you should find an alternate source (it’s likely too hard).

Bacillus thuringiensis subspecies kurstaki
Also known as DipelTM or ForayTM. This is a bacterium solution that when ingested by a caterpillar (Lepidoptera: moths and butterflies only), will produce toxins inside the larvae’s gut and kill it. After a few days, you will see dead, black caterpillar bodies around the foliage of the infested plant (which can be very satisfying). It is most effective against young, newly-hatched caterpillars (around 15 mm long or less). Spray the foliage (undersides too) and watch those canker-worms, gypsy moth and leafroller caterpillars die.

Fermentation Products of Microorganisms
Believe it or not, this is referring to a pest management product that is registered in Canada. SuccessTM is a natural compound, created from the fermentation process of a bacterium (we don’t know much more than that). It functions by attacking the nervous system of insects. It works very well against many types of larvae (Lepidoptera: moths and butter flies; Hymenoptera: wasps and sawflies; Coleoptera: beetles). It also seems to be effective on all instars (ages) of larvae. Visit www.bayercropscience.com for the Success label in Canada.

Entomopathogenic Nematodes
You know these guys, the microscopic nematodes that swim into the natural openings of insect larvae. Once inside they deliver the pathogenic bacteria that kill the larvae. The nematodes then feed on the dead larvae and multiply inside the body. Note the word “swim.” They need soil moisture in order to swim to their host, so keep the soil/media moist (not sopping wet) at least two weeks following application of these nematodes. They are not hardy in Ontario. They will need to be re-applied in the spring and are generally active when soil temperatures are above 10°C. Products such as Nemasys are lethal to root weevil larvae (black vine weevil, strawberry root weevil). Nemasys F are effective against larvae of fungus gnats. There are other nematode products being developed for boring insects (e.g. peachtree borer) and white grubs (European chafer).

Predators and Parasites
There are a wide variety of predatory insects and mites that will feed on insect and mite pests. There are those that are parasitic, they will lay their eggs into the body of insect pests (which will then eat them from the inside out). Now you know where all those crazy B movies came from in the 70s! There are many distributors of these organisms in Ontario and Canada (e.g. Plant Products, Koppert, etc.). More and more frequently, we are seeing information that will allow more attraction, retention and reproduction of biologicals in outdoor production settings. Most of these beneficial insects are attracted to flowers. They require pollen and nectar sources to supplement their diet and reproduce. So by planting ornamentals that serve this need, you can attract and propagate many species of beneficial insects in the landscape. Some examples of flowers that provide the needed pollen and nectar sources include: Alyssum, Aster, Chrysanthemum, Cosmos, Daucus, Rudbeckia, Solidago, Spiraea, Tansy, Yarrow and Zinnia.
Note. Most pesticide labels can be found on the electronic database of the Pest Management Regulatory Agency’s website: http://www.eddenet.pmra-arla.gc.ca/4.0/4.01.asp. Always read the label before applying any pesticide.

Contact Information

This column is written by Jen Llewellyn, Ontario Ministry of Agriculture and Food and Rural Affairs (OMAFRA) Nursery Crops Specialist

P: 519-824-4120 ext. 52671 • F: 519-767-0755
E: jennifer.llewellyn@omafra.gov.on.ca

OMAF website: http://www.omafra.gov.on.ca/scripts/english/crops/agriphone/index.asp

Nursery Landscape Agriphone: 1-888-290-4441

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