Dr. Curtis E. Swift

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May 24, 2012
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SWIFT: Make sure you use the right pesticide for the right pest

I spread imidacloprid next to the fence that separates my lawn from my neighbor just the other day. I also spread this insecticide under my hackberry tree. This systemic neonicotinoid insecticide will prevent leafhoppers from destroying the leaves on the Virginia creeper that covers the fence and will help control the gall insects that are disfiguring my hackberry.

The ground around the hackberry should have been treated last fall or earlier this spring, but even though the leaves are already damaged by these insects the recent treatment will help slow the disfigurement of any new leaves yet to emerge and help keep these insects at bay for next year.

This is the same product available for use to control white grubs, the insect that causes damage to lawns, and was the insecticide used in Palisade to eradicate the Japanese Beetle Infestation in that community. Imidacloprid is an amazing chemical derived from nicotine. Carrying a caution label, this insecticide is used as a soil drench on many of the crops we eat to include most vegetables and herbs. It is highly effective in controlling aphids, thrips, leafhoppers, plant bugs, and whiteflies as it moves through the plant tissue, poisoning insects feeding on the plant. It is very effective on soft scale insects such as the European Elm Scale. It is not, however, effective on hard or armored scale such as oyster shell scale that feeds on the bark of aspen, or lecanium scale. The latter scale has been showing up in large numbers on oak and even peaches.

Imidacloprid also is not effective on peach tree borer, lilac/ash borer, or other moth larvae. For the hard scales and moth larva we now have another neonicotinoid, dinotefuran, sold under the names Safari, Scorpion, Venom, etc. Black pine leaf scale is a pest of Austrian pine especially when they are drought stressed. Since this is a hard scale, imidacloprid is not effective. Dinotefuran, however, is a very effective treatment for this killer of pine trees.

More highly systematic than imidacloprid, dinotefuran can be applied as a trunk spray, foliar spray, or soil drench. The product I used for the leafhoppers on my Virginia creeper was a combination product containing both imidacloprid and dinotefuran.

I also spread this product around my asparagus to eliminate the asparagus aphids causing distortion and witches' brooming of the ferns. When asparagus is spindly and each spear takes on the appearance of a small bush instead being tall and leafy, the most likely cause is the asparagus aphid. A systemic neonicotinoid will kill these aphids and correct the improper growth characteristics of the spears. Even though these chemicals have a low mammalian toxicity and are applied to many of the vegetable crops you and I eat every day, each has a specific number of days you should wait between application and when the fruit or vegetable is harvested. Always read the product label before using one of these materials to be sure you are following the directions.

If you have peach crown borer in your ornamental plum tree or have a peach or nectarine with this insect problem, you could use Steinernema nematodes to attack and kill the insect larvae or you could use a product containing dinotefuran with peaches listed on the label.

Brant Harrison, an organic fruit grower in Palisade, uses Steinernema feltiae to control the peach tree borer larvae in his orchard. Applied at the base of the tree, these nematodes enter the soil and hunt out and prey on the larvae feeding on the root system and base of the tree. Nematodes are living creatures affected by the pH, salt level and moisture content of the soil, so care must be taken to ensure they are kept cool prior to applying them to the soil. Even then, they may not be as effective as a spray of dinotefuran.

About now one should be asking why I have been using the chemical names instead of a brand name. The main reason is the confusion brand names create. Products containing imidacloprid are sold under numerous brand names, and the manufacturers change the active ingredients in their named products as new chemicals or combinations become available.

In other words, the brand named product you buy this month may contain different chemicals a month from now. Reading the small print on the label that lists the active ingredients is best way you can ensure you are purchasing the proper product. You do that when you want a specific apple; you read the label stuck to the apple, so why not do that when you purchase an insecticide or other pesticide.

Dr. Curtis E. Swift is the area horticulture agent with the CSU Extension. Reach him at Curt.Swift@mesacounty.us, visit WesternSlopeGardening.org, or check out his blog at http://SwiftsGardeningBlog.blogspot.com.

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The Post Independent Updated May 24, 2012 08:41PM Published May 24, 2012 05:47PM Copyright 2012 The Post Independent. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.