Assessment of frost injuries after the recent frost event on May 9, 2020

Since the spring of 2016, Hudson Valley region has not experienced spring frost that has led to high level of flower injury. All odds were that 2020 would be that season, during which we would see frost injuries again. And it happened. Our first frost came on April 23, when most of our varieties were at tight cluster, with some of them in pink. Among observed varieties, ‘Empire’ was most advanced with 74% in pink bud and the effect frost had on it was the greatest with 58% flowers damaged. But that was not all. On May 9, while our apples were in full bloom, a weather station at HVRL recorded a low of 30.1 degrees F that morning. Two days later, I have sampled our South 40 block, taking randomly 20 flower clusters from each of the six observed varieties. Below is a table in which I presented flower damage and I put results of each frost event next to each other by flower type and as total, so you can see a cumulative effect these two frosts had.

Flower injuries after the frost on April 23 and May 9, 2020

Empire and ‘NY-2’ (‘Ruby Frost’) had lost 80% of flowers. Over a half of the total flowers were found damaged in ‘Gala’ and ‘NY-1’ (‘Snap Dragon’). The least percent of frost injuries was observed in ‘HoneyCrisp’ and ‘Fuji, which lost 1/3 of total flowers.

Frost injured ovary and stile turned form healthy green to brown

Having in mind that this is not the end of frost season and that we will see two more hits that are coming on Wednesday (May 13) and Thursday (May 14)  morning, the damage we recorded by now will grow even bigger. You can click on the link here where you can find some of the strategies you might employ to reduce the negative impact of coming frost.

Also, we have received reports about the frost injury on young developing foliage that showed as dark brown edges and red/brow spots on leaves (figure below).

Frost injury on apple flowers and foliage

While waiting to see the extent of the next frost, keep in mind that you only need 8%, 9%, or 10% of all flowers viable and pollinated to set a good crop.

Besides apples, I scouted our ‘Cabernet Franc’ and ‘Pinot Noir’ vineyard on May 11. Vines were  at bud break with some shoots reaching 3-inch stage, mainly in ‘Cabernet Franc’. Unlike pome fruit, grape young foliage and shoots are extremely sensitive to low temperatures. It is still early to say what was the actual extent of frost damage on yield, but it seems to be significant. Primary shoots that have reached 3-inch size all turned brown and soft due to frost. Secondary shoots will be less affected and will replace lost yield on primary shoots at some extent, but it is hard to say how much, especially if we know that another wave of cold temperatures is coming.

Frost injury on young ‘Cabernet Franc’ shoots

 

 

 

About Dana Acimovic

Mrs. Dana Acimovic has recently been appointed to the position of Extension Associate in Horticulture at the Hudson Valley Research Lab. Dana graduated with an MS in Horticulture from Michigan State University. She originally joined the Hudson Valley Research Lab in 2016 as a research support specialist in Jentsch’s lab. During the last four seasons, she has closely collaborated with post-docs in Dr. Robinson’s Lab in conducting evaluations of apple and cherry planting systems and rootstocks, as well as studies on precision thinning, pruning and irrigation. She has also led a new Cabernet Franc clonal rootstock trial at the lab. Her recent work also includes testing different strategies for minimizing sunburn damage on apple fruit. She plans to continue her work in many of these areas in her new position.
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