sour diesel is a clone only plant; which means it is hard to replicate because of its poly hybrid genetics; so real sour d only comes from clones taken from that mother plant. now some people have taken that clone and bred with it; and some people have tried to stabilize it by line breeding. A good breeder should be able to get preet close to sour d after a few generations with some keen selection. for example; i bought some " long valley royal kush " seeds that the maker made in mind with replicating sour D. now most of the plants ran definitely smelled & tasted sour d to me; and other people definitely comment on the disel smell. pretty good job on his part! here is his story on what he did; quite interesting stuff
"There are many styles of breeding that you can practice, it is not as simple as it may seem. Like I said before I am interested to reconsider breeding strategies and their affect on the cannabis seed market. Many companies out there would have you believe that stability is king, that uniformity is a necessity. Many breeders strive to create “in bread lines” (IBL’s). I agree that if you buy a package of ten seeds and you are expecting a certain strain you want the seeds to express the traits that are expected from that strain. Let’s take Northern Lights 5 as an example, NL5 is a stable, true breeding line and shows little or no variance in it’s offspring, it has been used as a progenitor (parent) to a lot of other strains, there are some that say Headband is a Northern Lights/Diesel cross. Many of the strains in today’s marketplace are poly-hybridized and only exist in clone form.
The Sour or New York Diesel is a perfect example, many breeders (myself included) have so loved the Diesel that they have tried to re-create it in seed form. The literature out there would have you believe that you can take any clone and “cube” it, that is take a clone and cross it with a male of similar taxonomy and then back-cross to the mother a couple times and voila, you have a population of seeds that are just like the mother. I am afraid it is not that simple, an IBL like northern lights which has true breeding dominant traits will probably cube easily, and in 3 or 4 generations most of the progeny will show all of the traits of the parent strain, however a highly recessive poly-hybrid strain like the Sour Diesel (13 different distinct traits) has a 1 in 64,000 chance of getting the allele alignment or “linkage” to occur for all of the traits to be expressed.
If you have ever grown the true Sour/New York Diesel, and those who have know, it only comes from clone. So the question remains, how do you get your favorite clone strain to grow from seed? Especially a strain with highly recessive characteristics like Diesel. The answer; develop strategies that are conducive to achieving the linkage necessary for the expression of the desired traits in subsequent generations."
http://blog.humboldtseeds.net/en/the-spice-of-life/
** this all said; i definitely prefer green crack over sour d; i forgot i really don't enjoy the sour diesel smell lol..