To develop an accurate economic threshold and alternative non-chemical control techniques to manage European corn borer damage in potatoes

Project code: PRR03-400

Project Lead

Christine Noronha - Agriculture and Agri-Food Canada

Objective

To establish an accurate economic threshold for European Corn Borer (ECB) infestations of potato and to investigate the use of mechanical methods to control the pest

Summary of Results

Determination of the economic threshold for initiation of chemical management of the European corn borer. In collaboration with provincial extension personnel, local farmers, and commercial producers, systematic trials have been carried out over a three year period to establish an accurate economic threshold for the European corn borer. This was done by artificially infesting potato trial plots with known numbers of insects, and then correlating these numbers with damage and yield loss. Field plots were set up at Harrington farms in PEI. Egg masses of European corn borer were used to established different infestation levels within these plots. At the end of the season the number of holes, tunnels and larvae on the plants were counted. Tubers were harvested and the yield was determined for the different grades of potato tubers according to the Canadian standard. Results show a significantly higher number of holes and tunnels and larvae per plant at the high infestation levels in both Russet Burbank and Shepody potatoes. Infestation levels corresponding to between 20 and 35% of plants infested showed no significant increase in the number of holes and tunnels, however, at 40% of plants infested or more, the number of holes and tunnels significantly increased. The number of holes in a plant could have serious consequences for potato producers, as a site for entry of disease organisms or leading to stem breakage during a wind storm. Results from this study indicate that growers who now use a 20% infestation level threshold could actually increase it to 30% or 35% without any significant increase in the number of holes per plant. In addition, the study shows that yield of small tubers increases at the 40% and above infestation levels; this is especially true in the long season Russet Burbank varieties. This pattern was not detected in the shorter season Shepody variety indicating that this variety may not respond negatively to high infestation levels mainly because tuber formation occurs early in the season when the larvae are still small and their impact is not as severe. Thus, thresholds could be increased from 20% to 30%-35% without any negative effects on yield for the long season varieties such as Russet Burbank, and to 40% for the short season varieties such as Shepody.

Development of the "ECB Crusher", a mechanical device to reduce ECB populations:
Researchers developed, tested, and conducted demonstrations of the efficacy of a mechanical device which crushes the potato stalks at harvest, thereby destroying the ECB larvae inside them. Reducing the over wintering population of ECB was demonstrated to reduce the colonizing population for the following year and is expected to help potato producers reduce the number of spray applications required, and their operating costs.

The device was tested on two potato varieties. Between 80-88% of the larvae inside the stalks were crushed, and more than 95% or ECB larvae failed to over winter and emerge as moths the next year.

The Crusher consists of two brushes and two metal rollers attached to a harvester just below the conveyer belt that discards the potato stalks back into the field. As the stalks come off the belt they are guided onto and pass through the two rollers before falling to the ground. The tension on the rollers is set to crush the stalks and in the process kill/crush the corn borers inside the stalks. The flexibility of the design of the crusher makes this device easy to build and attach to any harvester by simply adjusting the length of the brushes and rollers. It also allows a grower to harvest and control the insect simultaneously, thus eliminating the need for re-entry into the field to control this insect. All parts for this device are easily available for purchase, and blueprints are available from the research team upon request.

Factsheet on European Corn Borer Crusher for Potatoes

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