Grasshopper infestations in the upcoming 2005 growing season for the Weyburn region should range from very light or light to patches of severe infestation, according to the forecast map released by Saskatchewan Agriculture and Food.

The predictions were based on a survey of adult grasshopper populations observed by crop insurance staff, with data collected from over 2,400 sites to produce the map.

Most of the province will be very light to light for 2005, with only a few patches of severe infestations. The environmental conditions were not favourable to the development of grasshoppers, but the actual severity of an infestation will depend on the weather this spring, combined with the level of last summer's infestation in a given area.

In the survey, a population of 12 to 24 grasshoppers in a square meter rates as severe.

In the Weyburn region, a severe patch is forecast for the eastern half of the RM of Griffin and the southern two-thirds area of the RM of Tecumseh, along with the northwest corner of the RM of Cambria touching the RM of Souris Valley.

Moderate infestations, which is a count of eight to 12 grasshoppers in a square metre, are forecast for the RM of Benson, the west half of the RM of Cymri and the northern half of the RM of Souris Valley.

The forecast for a light infestation (4-8 hoppers per square metre) includes the RM of Fillmore, the west half of the RM of Griffin and the south half of the RM of Lomond.

Grasshoppers are forecast to be very light in the RMs of Weyburn, Brokenshell, Norton and the north half of the RM of Lomond. The RMs of Scott and Laurier are forecast to range from none to very light (2-4 hoppers per square meter), The Gap will range from very light to light, and the RMs of Lake Alma and Surprise Valley is forecast to be very light for grasshoppers.

A variable to the numbers of hoppers per square meter is that various crops have a different level of tolerance of how many grasshoppers can live there before severe damage begins, known as a crop's economic threshold.

In many cereal crops, the threshold is eight to 12 grasshoppers per square metre, while higher-value crops like high-quality durum can only handle about eight grasshoppers per square metre. For flax, their critical stage is the green boll stage, when the threshold is only two grasshoppers per square metre, likewise lentils in the flowering and pod development stage.

Canola is generally not a preferred crop for grasshoppers, and the threshold is more than 13 grasshoppers per square metre.