Re: sweet potato disease or pest?

Russ Bulluck (lrbulluc@unity.ncsu.edu)
Fri, 30 Oct 1998 13:03:08 -0500

On Oct 29, 1:10pm, Kevin Smyth wrote:
> Subject: sweet potato disease or pest?
> anybody out there know much about diseases and pests of sweet potatoes? We
> grew four varieties this year on our organic farm in S.E. Ohio and one of
> them was stricken by something weird, charcterized by deep black fissures
> and craters. Most of that variety is not worth harvesting because of this.
> What could it be? Nematodes? Fungus? Would greatly appreciate any insights
> on this.
> Kevin Smyth

Hard to say. Sounds like the russet crack strain of the Sweet potato feathery
mottle virus (SPFMV), but could also be root knot nematode (RKN), and secondary
infection with saprophytes. Could be soil pox, caused by Streptomyces ipomoea.

What type of "Disease Pattern" was there? Was the disease clustered around one
area or "patchy" in several areas (indicative of soil-borne diseases, such as
soil pox, or RKN)? Did it seem to occur at random? Was the entire field
affected? Also you said only one variety was affected? (These would more
characteristic of the aphid-transmitted SPFMV.)

Were there any above-ground symptoms? Did the leaves have chlorotic feathering
(yellowing around the Mid vein)?

There are tests for these diseases. Have your extension agent check it out.

-- 
Russ Bulluck
Graduate Student
Plant Pathology
NCSU
Box 7616
Raleigh, NC  27695
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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
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