whats causing dirty looking grapefruit

[redster]

what is this on my grapefruit?  you can see a few fruit that just look dirty, and one next to them in the background that's still green. this isn't dirt, or anything like sooty mold. whats causing this?

[HMHausman]

Hard to see, the picture is blurry.  Have you considered citrus scab?

[Millet]

Hard to see your picture clearly, possibly scab or sooty mold.   If so itshould be able to scratched off the rind with your finger nail - Millet

[redster]

I don't think its either. too light colored to be sooty, and don't look like any scab ive ever seen. ill try to get a better pic tomorrow, I didn't realize the front fruit was so blurry

[redster]

you can see it scrapes off with a fingernail, but the peel under it isn't right, its definitely affecting the peel...it still doesn't strike me as scab? nothing I searched came up looking like this.
the second picture is just cold damage from the winter, I think unrelated, but in the interest of full disclosure. my tree doesn't have canker anymore, but I do have leafminers, a little greasy spot im working on, and generally seems to be in decline. I had 500 fruit last year, and this year there is barely 100 on the tree, do they usually alternate produce?

edited....the more I look at the cold damage the more it bothers me that my tree is dying. if the bark is the most important part for transfer of nutrients, then I have a problem here, there isn't much left. it didn't get that cold last year compared to the year before, and I didn't cover it thinking it would be ok, but the rootstock obviously didn't like it...think I killed my tree?

[Millet]

Looks like what is normally called Sharkskin, a silvery type coloration, caused by citrus rust mite feeding on early season (green) fruit ,especially grapefruit . Citrus  rust mite damage on late season fruit (mature) gives a rust/brown coloration.

https://www.google.com/search?q=shark+skin+on+citrus&biw=1280&bih=854&tbm=isch&imgil=W6LLphc-oqokkM%253A%253BeH1g1xOjJ9gt0M%253Bhttp%25253A%25252F%25252Fagridr.in%25252FtnauEAgri%25252Feagri50%25252FENTO331%25252Flecture17%25252F015.html&source=iu&pf=m&fir=W6LLphc-oqokkM%253A%252CeH1g1xOjJ9gt0M%252C_&dpr=1&usg=__AjTNykWjRs_gOoWCg3yWDHhTMjk%3D&ved=0CEcQyjc&ei=ZbeFVdKiM8u3yATet7_YDg#imgrc=GZ-XA-j6a88MqM%253A%3BdDNsTUQFVI8J9M%3Bhttp%253A%252F%252Faggie-horticulture.tamu.edu%252Fcitrus%252Fdiagnostics%252Fblemishes%252FDscn0179a.jpg%3Bhttp%253A%252F%252Faggie-horticulture.tamu.edu%252Fcitrus%252Fdiagnostics%252Fblemishes%252Fsharkskin.htm%3B800%3B600&usg=__AjTNykWjRs_gOoWCg3yWDHhTMjk%3D

As far as the root stock trunk damage,I'm not sure, but you might look up phytophthora foot rot

Millet

[redster]

well see that sounds about right. I have spider mites on my tangerine, and it didn't occur to me that it might be something related causing completely different damage...my mature fruit had the red rust, but the timing for it made me think it was cold damage also...I considered phytophthora, at this point I honestly don't know, its certainly been wet enough, but this is the only tree getting it. I guess either way there may be no saving it...


so whats the best to use on the rust mites for such a heavy infection?