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Cornell Fruit Resources: Berries

Resources for Commercial Berry Growers

Cold Damage Report on Berries

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Flowers under row cover did not survive the freezing temperatures.

May 20, 2020 Berry Update

By Laura McDermott and Esther Kibbe

Reports are coming in from across the area on the results of last week’s unprecedented freezes. For Western NY, unless you had perfect frost protection,

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Angular leaf spot is showing up on plants that received frost protection (sprinklers).

most fields I’ve seen have 50%-75% of primary (king) flowers in early varieties killed by freezing temperatures. These flowers will open, but with black centers. Secondary and tertiary flowers will open and should be fine, but the first picking will be later than if the primary fruit had set. Later fruiting varieties might end up looking better as the buds were still deep in the crowns. Growers with row covers who ran sprinklers over the top had fairly good results. Using row covers alone was not effective in protecting the flowers, causing near complete bud death. For growers who used sprinklers for frost protection, angular leaf spot

(Xanthomonas fragariae) is now a major risk. I’m already seeing it show up in significant levels in some fields. It can severely damage leaves, reducing photosynthetic area. If it spreads to the calyxes of the berries, it can be very unsightly and may be unmarketable in some outlets.

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Ice formation on blueberries during frost protection.

Blueberries were still at pink and I haven’t seen damage in any fields. Some growers used frost protection just to be safe and it was cold enough to make an impressive amount of ice.

Eastern NY: Frost events all last week caused varying degrees of damage as temperatures were inversely cold as you went south in the region, and that is where bud development was most progressed.

Much, if not all, the early varieties of June bearing strawberries were lost to freezing temperatures from Albany south.  Some farms were able to irrigate on the final night of the nearly 5 day frost event – that night may have been the coldest as winds died.  The irrigation over plants and even over row covering may have helped save some of the secondary and tertiary blossoms that were not damaged during earlier, high wind frost.

For the most part blueberries were unscathed.  Some of the most southern regions where bloom had begun may have a significant loss in early varieties.  A few areas that had temperatures dip into low 20’s will likely see loss even in varieties that were still in early pink.  I am still optimistic that damage will be sporadic and a good pollination season will help encourage fruit set.

Raspberry growers report flower and even leaf damage due to the cold windy weather.  These plants will bounce back.  Winter cane damage in blackberry that is just showing up now is not unusual.  Flagging buds on some canes could indicate winter damage, but also look for root zone pests or disease that could spell more long term trouble.

Other Concerns:

Girdled strawberry buds caused by strawberry bud weevil (clipper) has been seen, as well as tarnished plant bugs in two Capital District plantings, and are likely throughout the region.  Don’t spray insecticides in bloom, but scout fields near hedgerows first.  If you see 3 clipped primary buds/meter of row that is the treatment threshold.  The challenge is that spraying insecticides during bloom is strongly discouraged, so scout before bloom in your mid and late season varieties.  Brigade, Danitol, Sevin can all be used and Pyganic will help organic growers.  Also, don’t mow adjacent hay fields – that will drive clipper and TPB into your berries – as well as early leafhoppers.

Scout for the tarnished plant bug nymphs, shake 30 flower clusters (six clusters in five different locations) over a plate. If four or more of the clusters out of the 30 sampled have any nymphs, control measures should be taken. Insecticide options include Assail, Brigade, Danitol, and PyGanic.

Fungicide applications right before bloom will help prevent fruit molds and some canker diseases.  Indar, Bravo and Tilt have been shown to provide best protection for wide variety of diseases.  The timing needs to be perfect and we are likely past the window for all but most northern plantings.  If you missed this spray this year – make a note in your phone calendar for early April to try and get this spray on the plants at the right time.

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Cranberry fruit worm

Monitor for cranberry and cherry fruitworm.  Pheromone traps can be used to monitor male populations of these pests and helps to identify the initial flight into a planting.  Lures are available for both species.  Traps should be placed during bloom with a minimum 50’ buffer between them.  Monitor trap catches twice weekly and remove moths caught each time you check in order to identify when sustained captures occur. Secondary scouting can be done for egg laying by inspecting the calyx end of green fruit with a hand lens.  Scout the periphery of the planting especially near woods and hedgerows.  Imidan, Asana, Lannate and Exirel are all labelled for control at petal fall.  If you’ve had this problem before, be ready to control these pests.

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