It has been almost three weeks since we had the bitter cold snap on April 5^th. Early that morning (around 5-6am) temperatures dipped into teens and below around the state - it was actually 2F here at my house. We’ve had several other cold nights that may have added to the damage, but were in no way as threatening. The absolute temperatures on April 5^th were very location dependent and ranged from near zero to the high teens. Depending on the stage of development, and assuming somewhat of a linear relationship between stage of bud development and temperature, most growers could have expected to experience conditions that resulted in at least 50% mortality on fruit buds - some more, some less. But do we really understand how damaging the freeze was? And what are the management implications? We’ll get to these items in a minute.

There are three levels of damage I have been looking at, each an increasing level of concern – each will have its impact on management decisions and production this season.

Fruit Bud damage – Stage of bud development ranged from at ½” green in the lower Hudson Valley to silvertip in the Finger Lakes and colder regions. However, most areas were showing some green. Stage of development was also variety dependent. For 1/2" green the critical temperature thresholds were 23°F (10%) and 15°F (90%) – meaning that approx. 19°F was the critical temperature where 50% bud damage could be expected. Overall, it appears that on average 40-60% of developing flowers were killed outright in all locations – with some varieties like Red Delicious and Empire taking the brunt of the damage. Surprisingly, others like Gala and Ginger Gold didn’t suffer too poorly. Unfortunately, certain varieties we might expect to be more resistant didn't seem to fare any better or worse than the rest and the low single digits experienced in the Catskills and Finger Lakes caused a lot more damage than in other parts of the state..For most growers, this level of damage leaves plenty of flowers to set a full crop – if there are no more issues along the way.

Spur Leaf Damage – even though the fruit buds generally fared better than expected (if you believed the critical threshold charts), the spur leaves in many cases did not. There is a lot of crinkled, burnt and outright dead spur leaves. The spur leaves are what support the earliest stages of fruit growth and without optimally functioning spur leaves, the developing flowers and tree growth can stress the tree beyond its capacity to support them optimally. This doesn’t mean that damaged spur leaves mean all the flowers will just drop off or that there won’t be a crop. It does mean that as growers (and consultants) we need to do everything we can to not overstress the tree or further damage the spur leaves. In essence, make sure your tree is in optimal health, with adequate moisture and nutrition, but don’t push it to grow faster than it wants to.

Spur Wood Damage – this is the most concerning area in our book and in our opinion is not related to the April 5^th freeze. Looking back, we had a very mild winter right up until the Valentine’s Day freeze where temperatures across the state dipped in the negative double digits. After such a mild winter, and lower level of tree hardiness, these temperatures likely caused the spur wood damage we've been seeing. That’s our take on it anyway. In cutting literally thousands of buds over the past two weeks, I have become acutely aware that there is a wide range of damage to fruiting spurs and underlying wood. It ranges from mild yellowing of the receptacle (where all the flowers attach) and the underlying wood and vascular tissue, to serious browning, water-soaked appearance, and even what appears to be the development of an abscission layer between the fruit bud and the spur. This level of damage could have a significant impact on the ability of the spur to support developing flowers and subsequent fruit. Many fruit buds, even though they appear healthy using the classical dissection method, may not even make it that far.

Below are a few examples of what we've been seeing. 



Far be it for me to run around like Chicken Little, because this damage could turn out to be nothing. There is great opportunity out there and if managed correctly could result in a very healthy, somewhat normal crop. But if the damage is more than it appears or if it is mismanaged – so instead of Chicken Littles we become a bunch of ostriches with our heads in the sand – then we could do more harm than good.  There isn’t any way to undo the damage done, nor is there any practical way to properly assess the sublethal damage to surviving flowers and fruiting wood that will affect fruit set, thinning, fruit shape, size, and russeting, as well as June Drop, fruit maturation and storability. So we have to approach the situation with caution. Our approach will have to be very Hippocratic – Do No (more) Damage!

Going Forward – How the spur wood damage really plays out still remains to be seen. There is definitely some damage that is minor and/or healing itself; other damage not so much. I will reassess everything again this week. And after a few days of incredible weather – warm and sunny – surviving buds will have really started to push and this is when the true degree of damage can become more apparent. Can the tree support the developing buds and tree growth? Only time will tell.