Frequent rains in May and June have soaked many Manitoba potato fields and made it difficult to finish hilling and weed control herbicide sprays, especially in poorly drained fields. Vikram Bisht, plant pathologist, Manitoba Agriculture, reports that cumulative rains from May 1 to July 2 were 170 to 226 per cent of the 30-year normal. From June 24 to July 2, there was 37 to 100 mm rainfall in potato growing areas of Manitoba.

In general, most fields appear to have good stand and plants are more than 24 inches tall in early planted fields. Most fields are nearing row closure; two to three protectant fungicide applications have been done in many fields.

Tuberization is at different stages, from initials to more than three-inch size.

The late blight risk forecast model suggests low to moderate risk if the pathogen was present. No late blight spores were detected in the 14 sites with passive spore traps; but nearly all sites were positive for early blight spores. Early blight has been reported in western parts of Manitoba.

Colorado potato beetles are active and multiplying in most of Manitoba, but more in the southern potato growing areas of the province. The aphid count in the aphid traps continues to be low in the second week of reporting; buckthorn aphids were found in two of the three sites. More aphid samples are expected in the coming week. More incidences of potato mosaic virus symptoms are appearing in a few fields. There is a forecast of scattered showers or rain from July 6 to 8. 
 

Source:  Manitoba Potato Report July 5, 2024