By Kathryn Carter, Dr. Wendy McFadden-Smith and Amanda Green, OMAFRA


The hot weather has continued to push degree day accumulations (GDD) forward and as of May 25, 2020 the GDD from this year are now ahead of last year’s growing degree day accumulations. The GDD accumulations for 2020 (base 5 °C) for the Niagara Parkway South area are 365 GDD, as compared to the 6 year average (2014-2019) of 411 GDD.

Day time high temperatures over the past week have ranged between 16 to 31 °C. Currently the long range forecast for Niagara is calling for June to have normal temp and precipitation except a bit hotter and drier next week. July is expected to have normal to slightly hotter temperatures with normal precipitation. August is expected to have normal temperatures and precipitation.

Tender Fruit and Fresh Grape

Hail damage

Storms on Tuesday June 2 resulted in heavy rains and hail damage in some crop growing regions. Hail damage is expected to be less in the Vineland and Jordan areas. However, there are reports of more significant damage in the Fonthill area where the hail was more severe. The extent of the hail damage has yet to be determined.

Crop Development:

In Niagara and southwestern Ontario apricots, plums, peaches and nectarines are sizing up nicely with the warm weather we have been having. We are seeing some strange pigmentation in peaches and nectarines that likely is a result of the cold temperatures/frost experienced in May (Figure 1). Pears have set fruit, but there is some rat tail bloom in orchards. Fresh grapes range from 30-40 cm of growth.

Pruning and planting of tender fruit trees continues. For orchards that have experienced significant crop loss due to frost, it may be of benefit to delay pruning, to help mitigate the excessive vigour caused by the reduction in crop. However, in orchards where structural damage occurred (ie. due to the cold temperatures in November), it would be of benefit to prune injured trees earlier, to allow adequate time for regrowth and training the replacement structure.


colour pigmentation peach

Figure 1 Peaches with different colour pigmentation (Courtesy of Joe Dutchyn)

Pear Thinning and Size Enhancement

Applications of 6-BA (active ingredient in Cilis Plus and MaxCel) can be applied now for size enhancement and at 5-14 mm diameter for fruitlet thinning. The MaxCel and Cilis Plus labels are slightly different from each other for pear thinning and size enhancement.

  • With MaxCel for fruitlet thinning, sizing and enhanced return bloom, apply 50-200 ppm at 8-14 mm fruitlet diameter and do not apply more than twice per season.
  • With Cilis Plus for fruit size enhancement, apply 2-4 applications of 10-50 ppm starting at petal fall continuing at 3-to10-day intervals. For fruitlet thinning apply 1-2 applications of 50-200 ppm at 5-10 mm in fruitlet diameter.

Diseases/Pest Management

Fire blight risk was high for hail injury following a week of extreme risk for blossom infection. Fire blight strikes showing up now.

Wine Grapes


Storms on Tuesday June 2 resulted in heavy rains and hail damage in some crop growing regions. Hail damage has been reported in Vineland, Jordan and the Fonthill area. The hail occurred pre-bloom, and the extent of the damage is expected to be minimal.


Crop Development

Vitis vinifera cultivars in range from 10-20 cm of growth with clusters apparent on many varieties (Figure 2). Vineyard planting is continuing and shoot thinning and suckering has begun.




Figure 2 Marquette, Simcoe, ON June 3, 2020 (Courtesy of Steve Buehner)


Pest management

Erineum mite and Phylloxera are starting to show up in Vineyards. Adult mealybugs were found this week.

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