RED DEER — The potato psyllid, which is responsible for spreading zebra chip disease, has been found in southern Alberta but so far has done no harm.
Researchers led by Dan Johnson of the University of Lethbridge found the insect in the potato growing regions of Coaldale, Grassy Lake, Taber, Vauxhall and the Blood Reserve.
Zebra chip makes potatoes unsuitable for frying because the flesh is marked with brown spots and stripes.
It was first documented in the mid-1990s in Mexico and has made its way north. Similar symptoms were reported by 2007 in potatoes grown in Nebraska, Colorado, Kansas, New Mexico, Arizona, Nevada, and California.
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Researchers also checked fields for eggs on the leaves of plants, but did not find any. About 80 percent of the insects were male, Johnson told Potato Growers of Alberta’s annual meeting held in Red Deer Nov. 18-19.
“To me that shows there is not a huge migration,” he said.
There are 30 types of psyllids, but this one has white ridges on the back and abdomen and sculpting on the back. Adults have triple branching of the wings.
Researchers suspected that in-sects found in Alberta would be the same as the Idaho varieties, but it appears they are the same as those found in Texas. That similarity leads to the conclusion that the insects may have been in the province for a long time.
“I think we have had potato psyllids here without the disease agent,” Johnson said.
Alberta producers do not spray many insecticides, which has allowed 20 natural enemies to flourish in potato fields.
“I think this parasitic community is keeping them out,” he said.
Johnson thinks the populations are higher than previously thought and wants more sampling. Getting a handle on the problem also allows growers to develop control strategies before trouble starts.
