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Pesticides – What are you recommending?

The entire pesticide situation for gardeners is in a state of flux as
older products are banned from the marketplace yet few new ones are
available.

The entire pesticide situation for gardeners is in a state of flux as older products are banned from the marketplace yet few new ones are available. 

In southern Ontario at least two relatively new pests are now very bad on rose bushes – the Japanese beetle (Popillia japonica) and the rose midge (Dasineura rhodophaga). Japanese beetles have been around, especially in the Niagara area, since 1939. Fortunately, they have not yet been found in Alberta or British Columbia, or for that matter, neither have they appeared in Atlantic Canada except for a very limited area in Halifax County. In B.C. the Canadian Food Inspection Agency (with the active support of the B.C. government) actively monitors for them with traps.

While various insecticides work well, most of those that do are either gone from or about to be gone from the marketplace – malathion, diazinon, chlorpyrifos and dimethoate (Cygon). One that does work, and is still available is Merit, but it is only available to commercial applicators. The old organic insecticides rotenone and pyrethrum also work, but there is no long-lasting affect.

One U.S. garden writer recommends a ‘home remedy’ – in a cup of water add two ounces of sugar, a mashed banana and a package of yeast. Place in a tub next to your roses and the beetles will want to drink this concoction. They fall in the tub, and you can remove them later.

Though traps are available the known fact that only about 3/4 of the beetles attracted by any trap actually go to it, means that the other 1/4 that are attracted to the plants, so they can be considered a negative. If traps are used, they should be placed at the perimeter of the garden, away from prize plants.

Now, thinking about the rose midge, let’s look at some recent research conducted for Doktor Doom, specifically their House & Garden Spray, containing 25 per cent Permethrin as regards its effectiveness on rose midge, and other associated insect, and as compared to other generally recommended (presently) insecticides. The work was carried out last year for Ultrasol Industries by Janice F. Elmhirst and Tanya J. Fletcher of Elmhirst Diagnostics and Research in Abbotsford, B.C.

 “Doktor Doom® House & Garden (0.25 per cent permethrin) applied every two weeks as a light aerosol mist over the plant foliage resulted in a 70 per cent reduction in buds damaged by rose midge compared to the untreated check, with negligible phytotoxicity. The number of damaged/infested buds was significantly less than in the untreated check or the Orthene T & O (acephate) standard.  Since the plots were not enclosed with screens, some damage could have been due to adult midges migrating into the trial area and between plots within the trial however a similar influx may occur in landscape gardens and nurseries during the growing season.

Monthly mist applications of Doktor Doom H&G  reduced midge damage by approximately 40 per cent.  Monthly soil applications of Doktor Doom H&G suppressed midge damage by 50 per cent compared to the check and provided effective control of aphids.

While the label of Doktor Doom House & Garden does not presently include mention of its use on rose midge, the Pest Management Regulatory Agency have given Doktor Doom a minor use label amendment to their House & Garden product to include rose midges. Obviously this is a product you can safely recommend for use this fall on the horrible rose midge.