Dr Eugenia Banks, potato specialist working with the Ontario Potato Board in eastern Canada, yesterday took a video of one of several spore trap devices in operation in the region. Click on the picture below to watch the short video (30 seconds).
Earlier this week Dr Banks reported in her regular email newsletter that most of the fields in central Ontario that were planted in early May are filling the rows, and she said tuber size is good so far.
Poor potato emergence was noticeable in a few fields. Banks suggests that possible causes of poor emergence are crusted soil, differences seed vigour, cold temperatures and frost damage. In mid-May parts of Ontario saw temperatures drop below freezing on some nights, prompting frost concerns for many vegetable farmers. In other jurisdictions, Banks says, glyphosate carry-over in seed is being investigated as the cause of poor emergence in fresh market potatoes.
More Colorado potato beetles seen by scouts
In her newsletter, Dr Banks mentioned that more Colorado potato beetles (CPBs) than usual are observed by potato scouts in Ontario. She asks: “if insecticide resistance is ruled out, what could be the reason for seeing more CPBs this season?”
“A possible explanation is that pre-cutting seed is more common than before,” Banks says. “When the seed is pre-cut and treated with an insecticide, it remains in storage for about two weeks until it’s planted.”
Banks says potato seed usually emerges three weeks after planting, and a week after emergence, CPBs may start infesting plants. “Thus, six weeks (42 days) after the seed treatment, the insecticide has lost some activity and CPBs are exposed to [a potentially] sub-lethal concentration of the insecticide,” Banks explains. “Something to think about.”
What does summer has on the agenda?
Dr Banks wrote in her newsletter: “A grower told me: ‘Whatever summer will bring to potato production is in the hands of Mother Nature’. I guess we can all agree on that!” She included a table outlining the potato diseases and physiological disorders (PD) that are likely to develop depending on the weather, noting that early blight is an endemic disease; it develops every year regardless of weather conditions.
|Cool and wet||Warm and dry|
|Late blight||Alternaria Brown Spot|
|Aerial Stem Rot||Black dot|
|Botrytis gray mold (PD)||Toxic Seed Piece Syndrome (PD)|
|White mold||Second growth (PD)|
|Phytophthora nicotianae||Fusarium Wilt|
Source: Dr Eugenia Banks
Photo: Example of “leaf burn” on a potato plant | Dr Banks