Biology Reference
In-Depth Information
10-day intervals, starting in January in Louisiana,
late February in North Carolina. Fairly resistant
varieties include Catskill, Midland, Fairfax,
Howard 17, Blakemore, Southland.
Septoria
Blights
.
Septoria azaleae
Azalea Leaf Scorch
,
Leaf
Spot
. Small, yellowish, round spots enlarge irreg-
ularly, turn reddish brown, with dark brown
centers. Leaves fall prematurely; black fruiting
bodies are produced in fallen leaves. The disease
is most severe in greenhouses in fall and winter
and under high humidity.
▶
Epicoccum
▶
Leaf Spots
.
Epicoccum sp
Leaf Scorch
on pecan.
Fusarium
Stagonospora
Rots
.
Fusarium sp
Leaf Scorch
on pecan.
▶
Deuteromycetes, Coelomycetes
Pycnidia dark, separate, superficial, or erumpent,
globose, ostiolate; conidiophores short; conidia
hyaline, typically with three or more cells, cylin-
drical to elliptical; parasitic or saprophytic.
Stagonospora curtisii
Narcissus Leaf Scorch
,
Red Blotch
of Amaryllis,
Red Leaf Spot
,
Red Fire Disease
, also on crinum, eucharis,
hymenocallis,
Hendersonia
Deuteromycetes; Coelomycetes
Pycnidia dark, separate, globose, ostiolate,
immersed then usually erumpent; conidia dark,
several-celled, elongate to fusoid; saprophytic or
parasitic.
Hendersonia opuntiae
Scorch
,
Sunscald
, com-
mon and serious on prickly pear cactus
(
Opuntia
). Segments turn reddish brown and
die; centers are grayish brown and cracked.
leucojum, nerine,
sternbergia,
vallota, and zephyranthes.
Leaf tips of narcissus are blighted for 2 or 3
inches as in frost injury and separated off from
healthy basal portions of leaves by a definite margin
or yellow area. Spores formed in pycnidia in the
dead area furnish inoculum for secondary infection,
which consists of lesions in lower portions of leaves,
minute water-soaked or yellowish spots becoming
raised, scabby, and reddish brown. Flower stalks
may be spotted; brown spots appear on petals.
Bulbs suffer loss in weight due to killing of foliage
a month or two before normal dying down. All types
maybeinfectedbutthemost susceptible varieties
are in the Leedsii and Polyanthus groups. The fun-
gus was described on narcissus in 1878 but was not
considered a threat to it, nor was it known to be
connected with amaryllis red blotch before 1929.
On amaryllis or hippeastrum red spots are
formed on leaves, flower stems, and petals. On
foliage the spots are bright red to purplish, small
at first but often increasing to 2 inches. Leaf or
flower stalks are bent or deformed at the point of
attack. This disease should not be confused with
Pestalotia
Blights
.
Pestalotia sp
Leaf Scorch
on pecan.
▶
Pseudopezicula
Ascomycetes, Helotiales
Hyaline, gelatinous apothecia containing paraph-
yses and 20-80 asci; asci contain four reniform,
binucleate ascospores; five-spored asci rarely
observed.
Pseudopezicula tetraspora
Leaf Scorch
of
grapevines.
