Where have all the flowers gone?

by Bill Lord, UNH Extension Professor Emeritus & Fruit Specialist

 After what seemed like a long and sometimes quite cold winter, we expected some loss of flower buds on peaches.  Newer varieties planted over the past several years had not yet been “tested” by a colder NH winter and peach plantings had been slowly migrating north.  So yes, peach bud losses have indeed occurred.  Better peach sites, generally located in the southern part of the State on elevated sites, are sporting relatively good potential crops while peach orchards on marginal sites have not fared as well.  Flower survival on individual branches is much higher near the base of those shoots that grew last summer while buds closer to the tips of last year’s shoots suffered heavier to complete loss.

What was not expected was a combination of a weaker than normal apple bloom while sweet cherries are sporting snowball bloom.  Where did all those apple blossoms go?

There are two distinct and separate issues affecting apple bloom this spring.  The most striking one centers on the individual flower clusters.  Normally, a flower bud on a spur or shoot terminal (as with Cortland) will produce a cluster of 6 (six) flowers – a center King flower bud that opens first and 5 subordinate flowers that open a day or so later.  The King flower potentially produces the larger fruit.

What would be the king flower is just a small stub surrounded by the 5 subordinate flowers of the cluster

What would be the king flower is just a small stub surrounded by the five subordinate flowers of the cluster

Well it seems the King has been deposed this year.  A large majority of flower buds have no king this year and often are lacking one or more subordinate flowers as well.  The remnant of the king, often appearing as a dwarfed appendage, is visible, but unviable.

Where did these Kings go?  A survey of the winter’s weather suggests an early hit…very warm temperatures through late November followed by the onset of real winter by December 8 or so is the likely cause.

The second issue is a bit more puzzling.  We had a very light crop in many orchards in 2012 due to a warm blast in late March followed by more normal temperatures in April of that year.  Freezes during bloom hit the crop hard.  In response to carrying a light crop in 2012, a very heavy return bloom in 2013 occurred.  A crop loss to frost offers the potential for a shift to a biennial bearing pattern.  Growers thinned aggressively in 2013 and based on the number and quality of fruit buds that developed it seemed they successfully thwarted this natural tendency to biennial bearing.

Oddly, many of what appeared to be strong flower buds are flower-less.  And not all varieties are affected equally with McIntosh and Cortland, our 2 hardy stalwarts, and Honeycrisp most adversely affected.   Why?  I can only speculate at this juncture but dense cloud cover and rain/mist over a 5-6 day stretch in early July, a key time frame in the flower bud developmental process may hold the answer.  Whatever the actual cause, when this is coupled with the loss of Kings, overall flower density is somewhat lighter than normal.

There is always a positive note in any situation and on the plus side, when flower density is low the percentage of those flowers that tend to set is quite a bit higher than when flower density is high.  But the real issue is how we manage this bloom and what predictably will be a heavier bloom in 2015 to effect more uniform fruiting.  Thinning decisions will likely cause much anxiety this season…normally we target our thinning strategies at the subordinate to favor the King apple.  I will get back with more on that in a week or so as the actual fruit set emerges.

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