I have a number of young citrus trees including Honey Bells and Orlando Tangelos. I have Dancy as a pollinator, but the bee population is pretty sparse.

Is the application of some Gibberellic Acid useful - and if so, should it be applied to the flowers or to the tree in general. Are there any rules of thumb?

Dale

Gibberellic acid works VERY well to pollinate citrus. In fact, gibberellic acid sets so many fruit, that some fruit thinning is beneficial to obtain larger size fruit. Spray 10 ppm solution directly on the open blooms. If you cannot easily find Gibberellic acid, Feti-lome's Tomato & Pepper Set II contains Gibberellic acid, and therefore also works. - Millet 1,386-)

Millet is correct about the setting of fruits.

Be careful about the concentration of the spray. Normally, to get an effect, you start off with 25 ppm GA3 and maximum of 50 ppm GA3. Apply during the peak bloom.

If you apply when the buds haven't opened, they could fall off, or revert back to vegetative growth, something that is desirable to control alternate year bearing. So to set fruits, the flowers should be receptive for pollination, and that is about during the peak bloom when most flowers are open.

If you apply too much GA3 such as those 500 ppm and beyond, you could absciss the flowers and they fall off, again, this is something that other growers may choose to do to thin out crops.

Most commonly, the farmers here in the citrus belt of California would apply 35 ppm GA3 to induce fruit set with adequate amount of fruit sets that do not require thinning out. If you apply the correct amount at the proper time, there would be no need for corrective measures.

So take great care in calculating the ppm of GA3 in your spray. The Ferti-Lome spray mentioned by Millet has about the correct range, but it is more expensive. I have jeweler's weighing scale to measure precisely the amount of powders or nutrients that I mix or formulate myself. If you simply use tablespoons or cups in your measurements, there could be a lot of inaccuracies in mixing.

Check out your local literature. The 35 ppm here is for the California Valley for most citruses. Different cultivars could have different rates. I'd start with a low rate like 25 ppm if I don't know about the local conditions. You can make two applications of 25 ppm spaced one week apart.

Thank you gentlemen for you quick response. I'll look forward to a bumper crop!

Dale

I believe that I have read on the UCR's site that gibberilic acid may have effects on when fruit ripens? What is the story with this?

Brancato, it is certainly true that GA3 can delay maturity, and delay the coloring of the fruit. To avoid this, just be sure to spray the tree no later that 4 months prior to the expected maturity date. When spraying citrus blooms to obtain a heavy crop, or to produce seedless fruit, there will, of course, never be a problem, as the expected maturity date from bloom to mature fruit is 6-10 months distant. - Millet (1,257-)

That's great information to know Millet. I do have a few seedless varieties which I would obviously like to try and keep that way. I have been hand pollinating everything on my baclony this summer already already as either being on the second floor might deter bees or more likely is the chance that our area has been hit hard by colony collapse disorder. That said, the Oral B Sonic-care toothbursh is a fantastic pollinator! Thanks as always Millet!

Joe

Actually, with very few exceptions, citrus are self fertile, and require no artificial pollination by man or insect to produce fruit. Hand pollinating certainly causes no harm, but is generally not needed. - Millet (1,267-)

For members who have larger mature citrus trees, that produce more fruit then the grower can readily consume, can turn to gibberellic acid for help. Two sprays of GA3 (10 ppm) also helps in retaining fruit on the tree for up to 4 weeks (a full month longer) beyond normal harvest time, thus facilitating on-tree storage, without affecting fruit quality at the time of harvest and yield of subsequent crops.- Millet (1,257-)

I do have a question then. My tomtoes are self-fertile as well but I was under the impression a bee/insect/wind was still neccesary to release the pollen to the female part of the flower (drawing a blank on what thats called right now)? I only ask because I was not really getting any tomatoes to set at the begining of the season but have had almost a 100% success rate since I have been using the electric toothbrush (it is kind of cool too, as soon as you touch the top of the flower w/ the toothbrush a little cloud of pollen wafts out). Is the case similar with citrus? I know citrus are self fertile but does it not still take something (bee/insect/wind/ect) to get the pollen to the female part of the flower? I ask because our bee population here is pretty scarce and am curious if I should assist this process in the spring when I get a flush of flowers? Is this even neccesary?

Joe

Don't confuse the need of tomato pollination with citrus pollination. Tomatoes do require some assistance with pollination to produce a full crop. With most citrus, if you did absolutely nothing at all, your tree will still set the crop of fruit. First, a citrus tree produces thousands of times more flowers than the tree would ever be able to sustain. If every citrus flower was successful in producing a fruit, the tree would be crushed under its own weight. For many varieties no artificial pollination is even desired, as it causes the fruit to become seedy. For example in areas in Spain, it is against the law to put a bee hive within two miles of any Clementine Mandarin grove. Citrus are capable of a process called parthenocarpy. In botany parthenocarpy (literally meaning virgin fruit) is the natural induced production of fruit without any fertilization of the ovules. If you interested in the process of parthenocarpy, use your computer and Google "citrus parthenocarpy". Take care. - Millet (1,256-)

I had no idea there was a differance between the two pollination-wise! This is what happens when you assume... Well, good to know the differance Millet, I googled it also and it all makes alot more sense now. Sorry to sidetrack the thread folks.

Joe

You did not side tract the post, besides yourself, your questions probably helped other people to better understand the process. Take care, your membership on this forum is appreciated. - Millet (1,256-)

to ensure my tomatoes are well pollinated, I go out in the early morning and just hold the plant stem near the top and give the bush a little shake. I always have plenty of tomatoes set, with plenty to give away.

I used to go out with art paint brush in hand, thinking that each bud had to be brushed. Not so! Even if you don't do a thing, you will still get tomatoes from the small breezes that pass by.

I was under the impression that citrus are wind pollinated also; that said I realize that the bees help the process along, and furnish good honey in the process. It's all a good thing!

You guys are uber smart Citrus nerds.