I am wondering if there is a certain age that is best for using a sour orange, Seville Orange specifically, like there is for Trifoliate Orange or if it just needs to be a decent size and if so, the proper width is a pencil size or is it bigger? Thank you for your help,
James

Yes, the diameter of the stem at the height you want to bud is the most important. If you plan to use a shield bud (a.k.a. "T" or "Inverted T"), the bark will need to be slipping, and that should happen about the time a flush of new growth is well underway, until just after it reaches full size. If you use the chip budding technique, then the growth stage of the rootstock is completely irrelevant.

I don't know where you are, nor where you get your scion wood, but be aware that it is important to use scions free of citrus tristeza virus if you're budding to sour orange, and if you live in a tristeza area (all of peninsular Florida, and some areas of California), you should avoid it as a rootstock altogether. On the other hand, if you are not in an area where your trees would likely catch it, sour makes an excellent tree -- cold hardy, high-quality fruit, salt tolerant, and considerable resistance to citrus blight and phytophthora root rot.

Dr. Manners,
Thank you very much for your reply. I luckily live in a non citrus producing area, or country for the matter (Canada), so sour orange is not a problem, the only problem is that I live in zone 5b and would rather live in zone 10 or 11. I would be getting budwood from the UCR virus free budwood so I would hope it wouldn't have virus or diesease. I am just starting to grow sour orange seeds so I am just trying to ballpark when I could hope to try budding, I am geussing 2-4 years if I'm lucky? I would idealy like to t-bud but would chip budding may be something I could try. I would just like to make sure that the rootstocks would be an appropriate size so I don't run into any problems, I have never budded before so I would testing it out for the first time as well.
Sincerely,
James

Certainly your growing conditions will be different from ours, but I'd think 2-4 years to budding size may be longer than necessary. We go from seed to budding size in 7-10 months, in a bright, warm greenhouse (90-100 F days, 80 F nights).

Malcolm

Dr. Manners interesting growth temperatures, in a northern greenhouse like Colorado and probably even in BC Canada 80F night temperatures would cost a ton of money. Even 100F day temperatures would have to be derived from artifical heat. One question, can tristeza virus be passed along through the seed into the next generation? - Millet

Dr. Manners,
Thank you very much for your help, I assume that I will just have to trail and error to see what an optimal age for budding in my conditions is giving maybe a year and try up to two years,
Sincerely,
James

Millet,
CTV is NOT transmitted via seed.

http://edis.ifas.ufl.edu/CH089

Andi

Viruses can be transmitted with budding knives, shears and inscects, it is advisable to dip the tools in clorox bleach diluted 1 part clorox to 4 parts water for about 5 seconds. Rinse well with water. It is best to do this between scions from different sources.

I finally found an article with good information and pictures about basic seedling care for rootstock and even different soil mixes used in:
Chiayi Agricultural Experiment Station, Taiwan,
which are stated by the site to grow the trees in roughly the same manner; The site has answered what I should be looking for in a suitable rootstock seedling, now that I see the size I'm glad that Dr. Manners mentioned that 2-4 years could be too long. Anyways here's the link:

http://www.fftc.agnet.org/library/article/bc52003.html

Sincerely,
James

None of the true virus diseases (tristeza, psorosis, etc.) is transmitted via seed, nor by knives or other mechanical means. However, the viroid diseases (exocortis, xyloporosis) ARE transmitted mechanically; hence the need to disinfect such tools.

Millet, of course we don't heat our glasshouses to such temps; we simply fail to cool them cooler. And as it turns out, citrus is perfectly happy to grow really fast, at high temps.

Malcolm

Dr. Manners, I knew in Florida, all you had to do was restrict the exhaust fans. Here in Colorado that could only happen during the late spring, summer and early fall. We are nearing 200 inches (5 meters) of snow on the ground not far west of me (Rocky Mountains). If you are a skier, this is the best year in the last 30 years for all the Colorado ski resorts. Powder 2 feet think in places. - Millet

Millet, here's hoping the South Platte drainage is getting that much moisture. I'm assuming I've guessed correctly where abouts you live and that you are on a municipal supply. Or, are you in one of the communities that gets water piped over from the Colorado?

Kent

Hi Kent, neither. I live on a farm and get my water from a well. Sounds like you know about Colorado. I live northwest of Bennett, Colorado a small agricultural town. The temperature outside at this time is 2F. - Millet

Millet, I lived in Longmont for 6.5 years until my career brought me home to California. In fact I moved there about the time that grapefruit on eBay would have sprouted. No clue who the seller is though.

On occaison I get back there to visit friends in Erie.

Kent