Posted: June 28, 2010

Adult female grasshopper. Courtesy: Dan Johnson

High moisture across many parts of the Canadian prairies has slashed the risk of grasshoppers becoming a significant crop pest in the region this year.

In a typical spring, the eggs of pest grasshoppers complete their growth and hatch around June 1, but only if the soil temperature is above about 15 C, says Dr. Dan Johnson, a professor of environmental science at the University of Lethbridge. "The rain and continued cold we have had this year has kept them waiting, and greatly reduced the potential. Normally, they would be out by now, but so far less than 10 percent of the eggs have hatched."

Some grasshopper eggs in areas yet to experience enough dryness and warmth are dying off but there is still a window for a portion to survive, he says. "Some of the rest of the eggs will die waiting, and the rest will hatch in July, if it warms up."

It's important to remember only a small portion of the vast population of grasshoppers pose a significant risk as a crop pest, says Johnson.

"There are around 80 species of grasshoppers on the prairies, but only about six are significant pests at the moment. The pest species tend to be the ones that lay large numbers of eggs when warm weather allows them to be active, hatch in the spring, and feed on emerging vegetation including crops. Some species feed on sage or thistle only, and they would never be 'pests.'" An integrated pest management approach that includes awareness of economic thresholds is key to sustainable grasshopper management, he says.

The eggs of the pest grasshoppers overwinter about an inch in the soil, so they are almost never killed by cold, says Johnson. However if there's a long day before temperatures warm up in the spring, as in the case this year, many do not hatch.

The impact of rain is all in the timing. "A little rain actually helps them, but only if it comes either the previous late summer, or in the spring before hatching. If it rains after they hatch, then a fair proportion of those new hoppers are killed off as well."

Johnson, previously a research entomologist with a strong focus on grasshoppers, has long been involved with the development of annual grasshopper forecasts and other grasshopper related information resources.

Recently, he assisted in the development of a manual for producers, titled "Grasshopper identification and control methods," which is available for free download on his website.

Posted: June 28, 2010

Dr. Dan Johnson

There will be reduced grasshopper risk this year through much of the Canadian prairies but a heightened importance on later scouting, says Dr. Dan Johnson, a professor of environmental science at the University of Lethbridge.

"The rain and cold in 2010 has reduced the early grasshopper risk to crops, pastures and grazing, and moved it to later in June and July," he says.

With this change-up to the grasshopper schedule, there have been some questions from producers about how to recognize the immature stages when grasshopper larvae return at that time. To help, Johnson has taken some photographs for those producers who want to be able to recognize the major pests, particularly the clear-winged grasshopper - pest of cereal crops, pasture and range - and the two-striped grasshopper, which is a risk to cereals, lentils, and pasture.

Here are Johnson's pics, along with some color commentary:

Focus on the key species. As a starting point, Johnson notes that larger grasshoppers found early in the spring, those with wings before mid-June, or any which make sounds, are not pests. "The focus of producers should be to recognize the immature stages of the key grasshoppers that actually threaten crops, which are the clear-winged grasshopper and the two-striped grasshopper. The key to successful scouting is to recognized the immature stages of these key grasshoppers."

Get digging. Producers can find eggs of the pest types by digging in the top two inches of soil, says Johnson. "The eggs look like brown rice."

Play detective. To identify the stage of development of the eggs, Johnson advises producers to first soak several of the eggs in one part bleach, two parts water for 10 minutes, which will clear the 'brown rice' look. "If you see dark eyes (photo to the left below ), they will hatch after a few days of warmth. If the egg and the embryo visible inside are white or clear (photo to the right below), they have weeks to go before hatching."

Dark eyes. Courtesy: Dan Johnson

White or clear. Courtesy: Dan Johnson

Zero in on 'instars.' Grasshoppers in the immature stages are called "instars," says Johnson, which come in five stages - first, second, third, fourth and fifth. "We call the newly hatched hopper a 'first instar,' or 'a first-instar grasshopper.' The first instar has no wing bud, since this has yet to grow, or ridge on the back. The second and third instars have a small ridge.

"The first-instar clear-winged grasshopper is black with a white, vertical stripe. The first instar of the two-striped grasshopper is light tan at first, and then darker brown by the second day (left and right photos below). The grasshoppers at the first instar stage are all about 1/8th inch in length."

Light and tan. Courtesy: Dan Johnson

Darker brown. Courtesy: Dan Johnson

The first-instar clear-winged grasshopper molts after a few days of heat, and moves through instars two, three, four and five, all of which are brown, not black-and-white like the first instar. "The black-and-white appearance is a signal that the hatch is recent and/or in progress," says Johnson.

Determine if control is needed. When pest species are identified, an integrated pest management approach that includes awareness of economic thresholds is key to sustainable grasshopper management, says Johnson.

A complete guide to the scouting process and related integrated pest management approaches for grasshoppers is available in a manual for producers, titled "Grasshopper identification and control methods." This is available for free download on Johnson's website.

Posted: June 28, 2010

CropLife Canada is among the groups taking advantage of the G8 spotlight to call attention to key issues – in this case, food security.

As leaders of the G8 nations meet in Toronto, CropLife Canada is calling for clarification and a reiteration of the G8 pledge to address food security made in L'Aquila, Italy, last year.

"In the year since the G8 committed to addressing food security and sustainable agricultural development through a US$22 billion dedicated fund, little clarity has been given on how much new funding is actually being committed," says CropLife Canada in a news release. Details are also lacking on how the funds will be used to make a difference to "the one billion hungry today, and the food and nutrition needs of the coming decades."

Among specifics, CropLife Canada wants the G8 to ensure that its action addresses the need to foster innovation, which it views as critical to food security. "The plant science industry is working to address this issue by providing farmers with tools to produce a safe, affordable and abundant food supply," says Lorne Hepworth, president, CropLife Canada. "In order to fully solve this global issue, it requires additional commitment and dedicated effort by governments around the world."

View the full CropLife Canada release.