Biology Reference
In-Depth Information
Scurf
Two diseases, one of sweet potatoes and one of
potatoes, are commonly called scurf.
from potatoes bedded in sand that has not grown
sweet potatoes before.
Monilochaetes
Helminthosporium (Spondylocladium)
Deuteromycetes, Hyphomycetes
Deuteromycetes, Hyphomycetes
Hyphae and conidiophores dark, spores hyaline,
one-celled, oblong-cylindric, in chains.
Monilochaetes infuscans
Sweet Potato Scurf
.
Small, circular, brown or black spots are formed
on all underground parts, often forming a uniform
patch over the whole potato or a black patch on
red-skinned varieties. The skin cracks, and pota-
toes shrink in storage. The black conidiophores
stick up from the surface of the lesions like bris-
tles. The fungus winters on the roots and on
decaying vines.
Control
Scurf, formerly present in 50 % of New
Jersey sweet potatoes, is now rare because of
proper care. Set only healthy sprouts, grown
Conidiophores dark, straight, septate, the upper
cells bearing whorls of conidia; conidia dark with
three or more cells.
Helminthosporium solani (formerly
Spondy-
locladium atrovirens
).
Silver Scurf
of potatoes.
Scab
,
Dry Rot
, present in almost all potato dis-
tricts but not too important. Light brown lesions
become somewhat blistered, giving the skin a
marked silvery appearance. The disease is only
skin deep, and control measures are seldom used.
Spondylocladium atrovirens (see
Helminth-
osporium solani
).
Silver Scurf
of potatoes.
Scab
,
Dry Rot
, present in almost all potato districts but
not too important.
