The 2003 grasshopper forecast for the Weyburn region shows a range from light to severe infestations, but the true picture of the grasshopper population won't emerge until spring, says the local extension agrologist.

Saskatchewan Agriculture and Food released its forecast for the province, with the southern and west-central regions expecting to have the most severe infestations in the coming year.

"For most of this area, the forecast indicates there may need to be spraying for most districts. There may be some variations due to specific cropping patterns on individual fields. Where there were peas or oats, for example, the survival of eggs is lower," said agrologist Elaine Moats.

She, along with the province's other extension agrologists, compiled data from 2,100 sites around the province to come up with the forecast map.

On the map, the RM of Weyburn area will have moderate to severe grasshopper numbers; the RM of Griffin is light to moderate; the RM of Lomond will range from light to severe, with a small patch of very severe; the RM of Wellington is mostly moderate with a patch of light and of severe; and the RM of Brokenshell is moderate, with a patch of severe infestation in the southeast corner of the municipality.

In the RM of Fillmore, grasshoppers should be moderate, with a severe infestation in the northwest corner; in the RM of Scott, the bottom half of the area is moderate, and the top half should have a light infestation; the RM of Norton will have an small area of severe infestation in the middle, and the rest of the area should be moderate; The Gap will be light in the top one-third area, and moderate to severe in the southeast corner; the RM of Laurier will have a moderate infestation in most of the area with an area of severe infestation in the northeast section; and in the RM of Cymri, they will have moderate infestation with an area of severe infestation along its western border.

According to Sask. Ag and Food, a light infestation is four to eight per square metre; moderate is eight to 12 per square metre; severe is 12 to 24 per square metre; and very severe is more than 24 per square metre. The economic threshold of grasshopper numbers also depends on the type of crop.

For most cereal grains, the threshold is eight to 12 grasshoppers per square metre, but for lentils in the flowering and podding stages, the threshold is two. For canola, studies show the economic threshold is more than 13 grasshoppers per square metre.

A number of factors will determine what the actual infestation will be, including weather and tillage practices.

If there is a cool, wet spring, egg hatching will be delayed and grasshoppers will develop more slowly. These conditions favour the development of diseases, and as Moats noted, a fatal fungal disease began to be very prevalent in area grasshoppers in late August and early September. The extent of this disease won't be fully known until spring. "If there's high humidity in the spring, there's a good chance the young grasshoppers will pick it up," said Moats. "Tillage is also a factor, where tillage exposes pods to feeding by birds or cracks the pods. They tend to dry out if the pods get cracked; otherwise the eggs are very well preserved," said the agrologist.

Female grasshoppers tend to lay eggs in areas with green growth. When hatching begins in the spring, farmers will need to check not only the main field areas, but field margins, fence lines, road sides and crops grown on stubble.