The convenience and effectiveness of the relatively new insecticide imidacloprid, the active ingredient in the products Admire 2F and Provado 1.6E make it appear to be the proverbial 'magic bullet' for Colorado potato beetle (CPB) control. In just four or five years, this chemical has reduced the regional population of this menacing vegetable pest to a fraction of what it once was. A single application can be so effective and convenient when compared to continuous scouting and multiple applications with other materials that even at $612/gallon (1998 price from a Connecticut supplier), it now dominates the market and has driven several other CPB products out of production.
However, let us not forget the hard lessons this pest has taught us in the past. This beetle can become resistant to any chemical it is exposed to continuously for six generations. At two generations per year since imidacloprid's release, we may start to see resistance problems in 1999. This material is already starting to lose its effectiveness in some potato fields on Long Island. (See the photo of CPB feeding on eggplant.) To preserve the effectiveness of this tool, we are going to have to practice resistance management. Another lesson has been learned. In the long run, multiple control techniques, Integrated Pest Management or IPM, will always outperform a strict reliance on a single tactic. Finally, we have learned to minimize the amount of pesticide used, to lower the risk from both obvious and hidden side effects (e.g. high price tag, pollution, toxicity, secondary pest outbreaks, etc.).
MINIMIZE THE AMOUNT OF PESTICIDE USED (COST ANALYSIS)
The in-tray or in-flat transplant drench technique is described on the Admire 2F label for tobacco and has been tested on and recommended for eggplant and tomato by Extension specialists and researchers at the University of Maryland and Rutgers University. It seems to be legal based on the general directions for use under chemigation that calls for applying Admire 2F "only through low-pressure irrigation systems."
Soil application at low label rate
The lowest dose that is recommended on the Admire 2F label for eggplant and tomato via various types of soil applications is 16 ounces per acre. This low rate has been shown to control 99.9% of the pests in an experiment where untreated eggplant had more than 27 beetles per plant. The cost of applying 16 ounces per acre is $76.48 at $4.78/ounce ($612/gallon).
Transplant drench at 1/2 ounce per
At a 42-inch row spacing and plant density of 6,270, it would take approximately 3.15 ounces per acre, at a cost of $15.06 to apply Admire with a standard watering can to transplant trays. Larger eggplant varieties such as 'Florida Highbush' may be planted at a density of 3,500 to 3,700 plants per acre so the costs would be proportionally less (around 1.75 ounces = $8.36/acre). Dr. Gerry Ghidia at Rutgers recommends applying the material in one pint of water per flat (1.7 to 2.6 gallons water/i 000 plants, 72 or 48 cells per tray) after allowing the plants to harden off properly. He has experienced a slight problem with phytotoxicity in some years, but not others, when plants were not acclimated to outside conditions. Transplants should be rinsed with straight water after application to wash the material from the foliage into the root zone and avoid delay of chemical uptake.
How long can you go? Maryland researchers maintained control (98%) and yields with a rate of just one ounce per acre after applying the diluted solution to individual transplant tray cells (plants) with a pipette (Dively et al. 1996). But wait, can we go lower?
Transplant drench at 1/2 ounce per
1,000 plants only in 10 border rows surrounding 10-acre field
You would have to treat 4,090 plants with 4.1 ounces of material to surround the perimeter of a 10-acre field with a barrier of protection (4.1 ounces per 10 acres = 0.41 ounces per acre at a cost of $1.96 per acre). Now your biggest problem may be that it may take you half a lifetime to use up a gallon of this stuff, especially if you do not have 10 acres of eggplant and tomatoes! This 'perimeter' treatment strategy has been successfully used in large potato, tomato and eggplant fields in Maryland and New Jersey for the past few years.
USE MULTIPLE CONTROL TECHNIQUES (IPM)
The bottom line. Use IPM, lower rates and resistance management and save money or return to the bad old days when nothing seemed to control this beast!
* Bacillus thuringiensis, rotenone and Kryocide
products work only on larvae. Best results are achieved when applied
just after egg hatch during warm temperatures.
**Other growers have recommended using this product prebloom only.
SELECTED READINGS AND REFERENCES
Dively, D.; J. Linduska; \ M.Ross;D. Baumann; C. Cain and M. Boltz. 1997. Colorado potato beetle control with transplant drench treatments of Admire to bedding trays of eggplant. 1996; Arthropod Management Tests. Vol. 22. p. 132.
Ferro, D. and R. Hazzard. 1990. Managing the Colorado Potato Beetle inNew England. Unpublished. pp.3.
Ghidia, G. 1998. Insecticide Resistance Management of the Colorado Potato Beetle on Eggplant in New Jersey. Rutgers Cooperative Extension. F5842. pp.4.
Olkowski, W.; N. Saiki and S. Daar. 1992. IPM options for Colorado potato beetle. The IPM Practitioner. Vol. XIV, No. 9. Sept. pp. 1-21.
T. Jude Boucher, Vegetable Crops IPM Program Coordinator, University of Connecticut Cooperative Extension System
Originally published: Yankee Grower, University of Connecticut Journal for Profitable Horticulture. Volume 1, Number 2 March/April 1999, p.7-9.
This information was developed for conditions in the Northeast. Use in other geographical areas may be inappropriate.
The information in this material is for educational purposes. The recommendations contained are based on the best available knowledge at the time of printing. Any reference to commercial products, trade or brand names is for information only, and no endorsement or approval is intended. The Cooperative Extension system does not guarantee or warrant the standard of any product referenced or imply approval of the product to the exclusion of others which also may be available.All agrochemicals/pesticides listed are registered for suggested uses in accordance with federal and Connecticut state laws and regulations as of the date of printing. If the information does not agree with current labeling, follow the label instructions. The label is the law.Warning! Agrochemicals/pesticides are dangerous. Read and follow all instructions and safety precautions on labels. Carefully handle and store agrochemicals/pesticides in originally labeled containers immediately in a safe manner and place. Contact the Connecticut Department of Environmental Protection for current regulations.The user of this information assumes all risks for personal injury or property damage.Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Kirklyn M. Kerr, Director, Cooperative Extension System, The University of Connecticut, Storrs. The Connecticut Cooperative Extension System offers its programs to persons regardless of race, color, national origin, sex, age or disability and is an equal opportunity employer.