Grasshopper concerns ahead for fall-seeded fields
By Tim Kalinowski
Grasshopper numbers may be tipping toward outbreak next year in southern Alberta, but much will depend on the kind of weather we get over the next six months, say the experts.
“Generally, it’s not real bad throughout southern Alberta, but we have kind of a hotspot we have been watching northwest Lethbridge County, the southern portion of Vulcan and over into Willow Creek,” confirmed Alberta Agriculture and Forestry insect management specialist Scott Meers. “That’s seems to be where the grasshoppers have built up. That’s the big problem area, but it does go quite a ways east and even a little bit into the north side of the MD of Taber. There are also possibilities elsewhere— we’re seeing on little red (hotspot) dot in 40 Mile.”
The types of grasshoppers are also a concern in this instance. In Carmangay and elsewhere in the general area, Meers confirmed four known major pest species were involved in the surge: Two-striped, Packard’s, clearwing and lesser migratory.
For historical context, migratory grasshoppers were associated with the grasshopper outbreaks in the 1930s. Packard’s, migratory and two-striped were all involved with the major outbreak in 1985-1986. Clearwings were the main culprit during the last major recorded outbreak in Alberta in 2002-2003.
Meers stated some farmers with vulnerable crops like lentils are already taking pre-emptive action in potential outbreak areas.
“We are seeing right in that really dry part near Carmangay we are seeing severe to very severe numbers,” confirmed Meers. “So it would be in the 20 plus range of grasshoppers per square metre. That’s getting up there quite high. “I have been warning any producers that are growing lentils to be particularly aware of their grasshopper numbers, because lentils seem to be unable to withstand feeding activity. They damage the pods and clip the pods off in lentils; so I have talked with farmers who are already moving ahead with spraying in their lentils because of that situation even though the grasshoppers may not yet be established in bigger numbers like we have seen in other parts of southern Alberta.”
University of Lethbridge entomologist and leading Canadian expert on grasshoppers, Dan Johnson, said while there is cause for concern, that concern must be kept in context.
“It is not a huge outbreak yet,” Johnson stated. “It is small and patchy, but it probably indicates something coming in the future. I wouldn’t say we are having a (widespread) outbreak right now, but we are teetering on the beginning of one if the weather promotes it.
“I am not concerned for this year,” he added. “I think there will be spot problems, but nothing like we have seen in the past.”
Meers agrees with Johnson’s assessment.
“In much of the area actually development in the adult grasshoppers is quite delayed this year,” he explained. “Their wings (as of the end of July) had not yet come out in lot of places and they are usually out and fully adult by the stage of the crop year.
“If they are late becoming adults then they lay fewer eggs. That affects the next year as well. That’s a positive we can take out of this current situation.” Johnson said it was also important to understand the different species of grasshoppers out there. Thanks to the weather, numbers are surging in some areas for more beneficial grasshoppers too, and it was really only those four pest species one has to be concerned about.
Farmers shouldn’t go around spraying willy nilly until they have identified the species they are seeing, Johnson said.
He also stated he was really more concerned for next year in terms of these problem species, and much of that concern is contingent on a mild winter followed by a dry, mild spring.
“They do the math,” he explained, referring to the four problem species. “They put out so many eggs that if they drop down to low numbers and conditions become really good for them— if a female lays 100 eggs and even if they only have 50 per cent survival; that’s a big jump, right? Then the following year, if they get 50 per cent again?
“For them it is a matter of math, and they are the kind of insect that lays a lot of eggs. Some of those species may lay 45 eggs in a pod, and lay three pods; so it is a fair number.”
Adding to Johnson’s assessment, Meers stated he also has some concerns for fall-seeded crops this year.
“That’s the only green thing around so the grasshoppers all congregate on those crops and makes it difficult to establish them in the fall,” he explained. “You can spray them out, but how many times can you spray? They are very mobile in the fall once they are winged.”