In most of Wisconsin, there has been very little rain since the middle of May and now into June, with limited rain the the forecast.
I have a heavy fruit set on most of my apples. Can I count on June Drop to thin the apples for me under dry conditions, or do I need to get out to my trees and start thinning by hand?
Clear sunny skies is probably going to hold the max number of apples on your trees. It’s cloudy weather that aids thinning. At least that’s my understanding. I don’t think you can depend on lack of rain to thin your apples.
It depends. If you have old trees and reasonable soil those roots are doing their thing waaaaay bellow ground. But there are also plenty of apple varieties that should be thinned even under the most spectacular of weathers, as the trees can hurt themselves overproducing. Some even turning biennial, skipping next year production so they can recover. Then there is the fact that you get to choose between lots of small apples or fewer better quality apples.
Lack of rain has definitely helped thin apples here in central MN. We’ve had around .2" of rain since early May.
Typically older trees do not shed but just ration and produce smaller fruit, unless you water them enough. If you want larger fruit thinning is a good idea before they reach the size of a quarter. By then you can also tell which ones are not insect infected.
Dennis
Kent, wa
Thin the trees, then turn around and thin them again. Then in the fall you can wonder why you didn’t thin more!!
At least, that’s been my experience.
we grow mason bees, and so have pretty extreme pollination, with many 5-6 fruit clusters. if we don’t thin early, then even with june drop etc. we’ll have a tendency to biennialization. however, if branch breakage is your main concern, then you can wait till june drop and thin overheavy branches that remain. all depends on your situation!
Quite a few of my clients have honey bees and although they are a serious presence in those orchards I’ve not seen much difference in fruit set between those who keep hives and those that depend on native pollinators. I’ve come to the conclusion that keeping bees is more important in mono-culture.
Also, I don’t know that lack of pollination is the reason some of the fruit in a spur set fail to fatten up. I believe there are other factors at play and trees send out more flowers than needed as a form of insurance.
But every site and region is different and if your experience is a before and after thing where the relationship seems certain, I don’t mean to contradict you. I’m only speaking from my own experience.
hi @alan, thanks for the reflection and i think this is an interesting question. it seems to me that it’s a pretty direct correlation. the trees closest to mason bee habitat have almost 100% 5+ fruit set per flower cluster, in years when there are plenty of dry hours during bloom. further away, or during wet blooms, the number go down significantly, with other things being more or less equal.
my understanding based on reading and experience, is that mason bee pollination and honeybee pollination work very differently. honeybees travel up to 1 mile or more, so their impact on pollination is not particularly localized. mason bees are much more efficient as pollinators (per bee), but they are also much more localized, rarely traveling more than 300 ft from their habitat, and preferring the very closest trees. this means that if you have truly large numbers of mason bees (like tens of thousands), you can have extreme pollination rates close to your habitat.
also, my understanding from fruit biology is that lack of pollination is the only reason a fruit fails to fatten. moreover, since there are several ovules to become seeds in each flower, the fruit size is also dependent on the number of times a single flower is fertilized – the more fertilized ovules, the larger the fruit.
if someone else has a different understanding of the biology, i’m all ears!
really appreciating this forum, thanks!
I am not criticizing your management practices, but how does this work if you are getting every single flower to set fruit? Is there “too much of a good thing”?
Do you have to practice aggressive hand thinning? Do you chemically thin? With which agent?
Before I took up thinning, I was getting biannual bearing, mature fruit clusters that were hard to harvest without dropping a lot of fruit on the ground, broken branches. This was especially with a Haralson tree.
It certainly doesn’t seem to me to be the only reason. In the last few years I’ve learned that ovules can be killed by cold events that don’t kill the male flower parts- I’ve had beautiful bloom of many varieties of Japanese plums and pluots that are extremely well tended by many species of pollinators including mason bees and fine weather following with no frosts and have almost no fruit set on many trees. This year it happened again from a single below zero morning on Feb. Species more hardened off because they come out of dormancy a bit later were OK, but some peaches and nects not as heavily set as on a normal year even though bloom was heavy and pollinators plentiful throughout bloom. At the time of the deep freeze, active growth was not visible yet, at least no green growth.
I am a licensed sprayer and I assure that pest pressure played no role.
As far as healthy ovules always setting when pollinated, I’d appreciate it if you could link me to a source as it is a piece of info I’ve never encountered or overlooked in books on the subject I’ve read. I tried to find it in a search and failed and would like to be sure your info is correct. It simply doesn’t jive with my experience. Too often I’ve seen well tended flowers drop from trees when nearby trees set heavily and the variation in fruit set just doesn’t seem to have anything to do with bee activity at many of the orchards I manage, including my own- year after year. I’ve always assumed that trees often drop fruitlets after flowers have been well tended, leaving many and sometimes almost all spurs devoid of fruit in a given tree. Maybe I’m missing something.
how does this work if you are getting every single flower to set fruit? Is there “too much of a good thing”?
yes indeed! i would not do this simply to get pollination – we sell mason bees, so grow more than strictly needed for our own purposes.
Do you have to practice aggressive hand thinning? Do you chemically thin? With which agent?
we hand-thin, and yes, it’s a lot of work.
As far as healthy ovules always setting when pollinated, I’d appreciate it if you could link me to a source as it is a piece of info I’ve never encountered or overlooked in books on the subject I’ve read.
great points, and good question. one immediate note: i tried to be clear that i’m talking about once pollen actually germinates inside an ovule and creates a fertilized zygote etc. just having bees visit the flower (especially honeybees, which are less efficient per visit) won’t always result in this outcome.
i did a super-quick search to find relevant examples of where i’m getting my biology – like probably lots of us it’s from lots of places over many years, and doubtless has gaps.
the above example mostly focuses on the negative – ie. what are the reasons that fruits fail to form?
one that it mentions is temperature related, ie. warm enough for bees but too cold for fertilization! that seems to describe your case. and this would doubtless also be varietal dependant, at least in part.
but it doesn’t describe causes whereby a fully fertilized ovules fails to begin to develop into a fruit.
(of course, trees still have agency here – ie. june drop – but my understanding has been that in the very early phase when tiny fruitlets stop and fall off, it’s generally lack of successful fertilization. i imagine there’s probably exceptions to this, as with most things, but i’ve never read about them.)
anyone else have resources on this matter?
thanks for the conversation!