Re: sweet potato disease or pest? (fwd)

Russ Bulluck (lrbulluc@unity.ncsu.edu)
Mon, 2 Nov 1998 09:29:23 -0500

On Oct 31, 12:10pm, Kevin Smyth wrote:
> Subject: Re: sweet potato disease or pest? (fwd)
> Russ - Thanks for your response. I have one of the potatoes in
> question on the desk beside me here. It looks like the moon, all
> pitted and scarred with deep furrows and ridges. The very shape of
> it has been extremely altered- its quite ugly, in short. There is a
> blackening of the skin around the edges of the furrows and ridges.
> The furrows are rather deep - on this particular potato, which is
> about the size of a softball, the furrows are up to a good half inch
> deep. But all of these pits and furrows and ridges are "healed over"
> - there are no open or oozing marks. Does this info give you a
> better idea of what the problem may be? All hunches are welcome!
> Kevin Smyth
> Far Corner Farm
> ab210@seorf.ohiou.edu
>

It's always difficult to diagnose over the phone (or over the Web), so I still
think that your extension agent (or a specialist at Ohio State) would be your
best bet. However, from your description, I don't think you have scurf.
(Although, as some have mentioned, I am an academic, and can't completely rule
the disease out.) The symptoms you described are not consistent with scurf
(which is usually superficial, and more important cosmetically). It may be soil
pox, although the lesions you described are again not consistent with the
disease. Soil pox (or soil rot) usually produces circular to irregularly
circular lesions usually less than 5 mm deep, but varies with cultivar?
Speaking of which. . .

What was the cultivar? Certain cultivars are more susceptible to soil pox or
the sweet potato feathery mottle virus (SPFMV). Jersey is highly susceptible
to the russet crack strain of SPFMV, while the Centennial is highly susceptible
to pox. What were the above ground symptoms (or were there significant
above-ground symptoms)? In susceptible cultivars, soil pox causes transient
wilting, bronzing and chlorosis, stunting,

It still sounds like russet crack sweet potato feathery mottle virus, but could
be nematode related, or soil pox. SPFMV-RC is mainly seen on Jersey, so if your
variety is different, then that may not be the culprit.

I realize I'm throwing alot of maybe's and could be's around, but it's hard to
say without being there. (If I was there if could _probably_ give you a more
definitive answer.) I hope that what I've said has been helpful.

Russ

-- 
Russ Bulluck
Graduate Student
Plant Pathology
NCSU
Box 7616
Raleigh, NC  27695
-------------------------------------------------------------
The soil population is so complex that it manifestly cannot
be dealt with as a whole with any detail by any one person,
and at the same time it plays so important a part in the soil
economy that it must be studied.
--Sir E. John Russell
The Micro-organisms of the Soil, 1923
-------------------------------------------------------------

To Unsubscribe: Email majordomo@ces.ncsu.edu with "unsubscribe sanet-mg". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest".