Hello,

I have several semi dwarf apple trees that seem to be falling into a every other year heavy cropping pattern. I thought I had read somewhere that heavy thinning this year may break that pattern?

The trees are 4 year old harlson, gala, cortland, winesap..... any thoughts or recommendations?

Trees are located in Umatilla county Oregon .

dan or

I have thinned apples as late as July 4th on a farm in order to get decent sized apples.

But thinning apples to help with a biennial pattern is a different story......and generally the EARLIER you thin the better your results will be to help settle the tree into a more regular bearing pattern. The earlier you thin, the more effectively you can "communicate" to the auxins in the tree to produce bearing fruit for the next year by thinning it now.

If you had a light crop last year then maybe this year it would be good to do some thinning as you anticipate a big crop this year but a poor crop the next year if you have a biennial pattern......the earlier you thin the better. Some people even thin the blossoms now....but that is risky if you don't know which blossoms will bear fruit....so if you do that, be conservative. Most wait until they see the fruit and then thin the fruit out to 6 to 8 inches as soon as the fruit is visible.

Some will wait until after June drop and ensure that they know which fruit remains on the tree, but that is too late to effectively control the biennial pattern.

The Good Fruit Grower recently had an article about an "Equifruit Disc" that will be used to scientifically gauge just how much fruit to leave on any given limb.......it is my belief that super-hobby enthusiasts will start to work in this direction in the future, but for right now that is too tedious....and the usual rule is one fruit per cluster (select out the bad ones) or 6 to 8 inches between fruit.

http://read.dmtmag.com/i/57720/15


Final Note: Seattle will reach a sunny 70 degrees on Sunday. I will make a "bet" that this year both Portland and Seattle will finally get a good fruit set year after two bad years in a row where we have had wet and cool Springs. Therefore, if I am right, this year would be a good year to thin on some of the trees.
.

It probably goes without saying, but just to be clear: For anyone who had a GOOD fruit set last year, then do NOT thin the apples this year if you expect that your trees are biennial.....
you definitely do not want to thin if this year is likely to be bad, of course.

the only people who would do that are people who have a Golden Delicious or Akane or some tree like that and they know they get too much fruit every year.

What Don mentions above about not wanting to thin in a so-called "off" year but rather during the "on" year makes good logical sense. If this is the year when you expect a lot of fruit, then this is the year to do thinning.

I recently read an article that said that it is the SEEDS of the fruit that give off a chemical that inhibits the development of fruit for the following season. I'm not sure exactly how this works, but essentially it is best to do the thinning by removing blossoms or entire fruit buds rather than waiting for the fruitlets to begin development because by then the fruit is already seeded and starting to give off those inhibiting chemicals. I think the best thing to do, again, during the "on" year, is to remove about 50% of your fruit buds before they even have the chance to flower. This will go a long long way to reducing your fruit load and get your trees back on a more annual production schedule.

Best of luck to you.

As Don says, do it early. Within 40 days of bloom to communicate with the tree hormones for next year. Another useful thing to do is to prune the tree during the off year. It worked for me on my McIntosh, which was very biennial and no longer is.
John S
PDX OR

I had never thinned the fruit buds themselves or seen anyone do that, but only the fruit and so I wondered about this....but I see that in the case of some biennial varieties where crop load is sometimes too heavy and it is the biennial factor you are most interested in changing (rather than fruit size) then this is in fact done....I didn't know anyone did that....

http://apps.rhs.org.uk/advicesearch/pro ... px?PID=280


I'll have to think about this.....I would still suggest anyone trying this be pretty sure that they know the reason they are doing this is due to the biennial factor and that they be conservative in trying it at first.

(For example, what if the tree produced poorly last year because of some other factor and will produce poorly this year?....then, of course, thinning would be the wrong thing to do).

Thanks for this new idea.

Than ks! I will be thinning this weekend!

I know I thinned two years ago on the same trees.... must have been too late.

dan or

Our old pear tree is loaded again this year after about 2 yr of not much. Even branches that have not produced anything the last few years have a bumper crop. I was researching the subject of fruit thinning this morning and found this deeper explanation on the subject of alternative bearing.

http://ag.arizona.edu/pubs/garden/mg/fr ... nning.html

Both apple and pears have a strong tendency to alternate bear, that is produce large crops one year and no crop the next. Another important fact is that a spur will not produce fruit in consecutive years. Therefore the object in thinning is to eliminate all flowers and small fruit on every other spur. This has to be done within 30 days after bloom or the thinning will not be effective in reducing alternate bearing.

Has anyone removed all fruit from the alternating spurs as mentioned on trees that are prone to biannual bearing?

Reviving an old topic. I have two dwarf apple trees, a Fuji and a Braeburn, that tend to biannual bearing. I thinned them in the spring. When I thinned them it felt like I was removing most of the fruit. But at harvest time it was obvious that I had not thinned enough. There were multiple clusters of fruit. It was also obvious that where I did thin correctly, the fruit was much better quality. Does anyone else have problems thinning? I guess I just need to be more ruthless about it.