To assess the viability of the tree fruit crop after cold events, flower buds from varieties across the orchard can be removed from the branch and examined for freeze injury by slicing the developing bud longitudinally and looking for browning of the important flowering parts. These assessments help to simply answer the nagging question we all have… ‘what can we expect from specific varieties this season after these very low temperatures during pre-bloom freeze events”.
As we draw closer to bloom we may see temperatures drop again during the more vulnerable stages of flower development that further threaten our apple crop. We have already seen significant injury from the winter cold in February to peach, plum, apricot and nectarine throughout the Hudson Valley. This seasons very early tree fruit development coupled with a two day cold snap this week really took its toll on pome fruit. Hudson Valley growers who have crop insurance should contact their insurance adjuster at your earliest opportunity to inform them of freeze injury events and likely damage to your crop.
Our first assessment began the days following the coldest night of the year of February 14th, Valentines Day. We ran cold temperature assessments on apple, stone fruit and grape varieties a few days after the temperature dropped to -10.6F and found varying degrees of damage to grape selections, severe stone fruit injury with considerably more flower bud damage to NY2 then other apple cultivars.
We conducted a second assessment after the two cold temperature events we experienced this week, looking at bud survival in both our HVRL research orchard in Highland and a much colder site in west Marlboro. As this data was take a few days after the freeze events we consider it preliminary seasonal data. We will follow this up with successive assessments as the prebloom development period progresses.
To date the data sets below indicate a strong varietal difference in flower mortality in the two sites. The HVRL site low temperature was 18.9F for one hour while the west Marlboro site experienced 14.1F by 4AM on the 5th of April.
It’s important to note that this type of assessment may be of some help in providing a grower with a basis for crop load reduction estimates when done on a specific farm. However, it should not be used to estimate regional crop losses or to predict generic thinning adjustments until fruit set can be established, carbohyrdate availability and weather are taken into account. Additionally, the impact on the viability of the fruit, such as fruit shape and ‘frost rings’ that may appear on pollinated and set fruit is very difficult to predict based on these assessments.
The bud damage chart for the HVRL showed highest survival in HoneyCrisp 81.6% >Gala 80.4% >Empire 77.8% >Fuji 65.3% >Red Delicious 61.0% >NY-1 54.7% and NY-2 with only 35.3% sound flower buds. Damage levels for a west Marlboro apple orchard showed Golden Delicious at 80% undamaged buds > Granny Smith 63% > Jonagold 31.6% > Gala 23.6% > Ginger Gold 12.3% and Early Fuji with 6% live buds.
We can help in assisting growers with flower bud evaluations as needed and within reason, to help you evaluate this years crop viability over the upcoming weeks. All the best to you.