Bag or no bag after pollination?

[citradia]

I know several of you, like Ilya, have had success with hybridization. After some research here and elsewhere, I still want to know what actually works for hybridization on a mother citrus tree outdoors.

It looks like I need to remove petals of flower before it opens and imasculate the flower, then apply pollen from father tree. Do I then tie at mesh bag around the flower branch or a paper bag? It seems to me that mesh will allow other pollen to potentially get on pistil by wind, insects, etc. However, a brown paper bag will probably get rained on, get weighted down by water dogging it and causing it to slip off and/or damage the pollinated flower.

Someone suggested just applying the pollen before bees do and assume the end result is what you want.

What method works best for those of you who have successfully made hybrids?

[hear]

I have not tried hybridization yet, but I would probably think aluminum foil could work? During spring the heat is no where as intense as it is in the summer and you could probably seal it off from rain by tying the end of the foil. Just an idea never tried it out yet.

[kumin]

As you noted, there are several approaches used to prevent stray pollination. If the goal is making the maximum number of crosses, with the intended hybrids being easily distinguished from the rest of the seedlings, pollination, with subsequent removable of the petals may be adequate. Petal removal reduces bee visits. Citrus pollen is of the clingy type and not readily wind distributed like grass pollen.

However, for greater control I've always used fine plastic mesh fabric. This material didn't become soaked and water logged. The need for protection is short lived, only required until the stigmas lose receptively.

To enhance the chances of success I usually remove any extra flowers from the twigs unless I plan on making additional pollinations on following days.

Anther removal prior to dehiscence is important to prevent accidental self pollination. If the stigmas aren't receptive at the point of emasculation, they will still need to be protected until stigmas lose receptivity. I have found chances of successful pollination are improved by minimizing damage to the flowers.

[citradia]

Thanks, guys. It just occurred to me that when my trees bloom, other than poncirus, they will still be inside the portable greenhouses I erect around each tree for winter protection. The greenhouse will probably help prevent unwanted bee pollination too depending upon the weather and venting of greenhouse,etc.

[pagnr]

subsequent removable of the petals may be adequate

This was the method used by an Australian Citrus Breeder, with no bagging. They were doing many hundreds of crosses and growing 1000's of seedlings. Also discarding many seedlings. Maybe a few chance crosses that didn't fit their selection criteria would't matter ?
The bagging may have slowed them down too much.
I did see recently a bee working a petal less Citrus flower, so for a few crosses some isolation may be better.
The greenhouse is probably enough, I rarely see bees in my greenhouses here.

[hardyvermont]

I don't bag. Anthers are removed and pollen placed as soon as possible. The assumption is that sufficient pollen is applied and the earliest pollen does the fertilization so that a visit by a bee later on will not change the situation.

Not bagging reduces chances of damaging flowers/plant by mechanical injury. Removing nearby flowers increases chances of success.

[citradia]

Thanks, Hardyvermont. Makes sense to me.

[till]

I do it similar to hardyvermont. I pollinate the flowers several times as soon as possible and with plenty of pollen, so that the whole stigma is powdered. I only castrate the flowers when pollen and stigma are very close to each other. But even then, when I have plenty of flowers and hybrids can easily be recognized I do not castrate the flowers. I had, for instance, many Calamondin flowers that I wanted to pollinate with Poncirus. In that case I just pollinated the flowers and did nothing else. I got many hybrids. So I would say there is a safe professional procedure for cross pollinization but a good portion of pragmatism will help you to safe time and energy in many cases.
When hybrids are diffucult to recognize you need to safe the time of growing up useless seedlings. Then better invest in safe pollinization. But when hybrids can easily be recognized then better safe the time of castrating and bagging the flowers and pollinate more flowers that the chance of hybrids is higher.

[pagnr]

But when hybrids can easily be recognized then better safe the time of castrating and bagging the flowers and pollinate more flowers that the chance of hybrids is higher.

I had, for instance, many Calamondin flowers that I wanted to pollinate with Poncirus. In that case I just pollinated the flowers and did nothing else. I got many hybrids.

Overall I agree with your thoughts, but consider that you can recognise hybrids, but if any pollen comes in from elsewhere, they may not be the exact "hybrids" you wanted.

[till]

Some hybrids are easy to be recognized. When I pollinate Citrus and have no citrange and the like flowering nearby I know for sure that all trifoliate hybrids come from the Poncirus pollen that I applied. (Exception would be, so far as I remember, Kaffir Lime x Pummelo which is also trifoliate because of some archaic hidden genes.)
It is of cause not always so easy. For instance Citrus spec. x Citrange could result in monofoliate hybrids that have paired first leaves but still have a pretty good hardiness. I have such seedlings and now regret that I do not know what kind of hybrids they are. I do not yet dare to expose them to frost. So I have to care for them another year and do not know if it is worth it. Most hybrids of such crosses are, however, recognizable because they either have trifoliate leaves or alternate first leaves or a leave texture that reminds one of Poncirus or have leaves with Poncirus taste.
Citrus x Yuzu hybrids? Well, you probably must castrate the flowers and bag them. ...

When your pollinization procedure is lax you indeed need safe criteria for recognizing hybrids.