Blights - Westcott's Plant Disease - page 98

Ascochyta Ray Blight of chrysanthemum,
a conspicuous and rapid disease of ray flowers.
If young buds are infected, the head does not
open; if the attack is later, there may be one-
sided development of flowers. A tan or brown
discoloration proceeds from the base toward the
tip of each individual flower, followed by with-
ering. Upper portions of stems and receptacles
may turn black. Keep plants well spaced; avoid
overhead watering and excessive humidity.

scattered throughout the stromatic tissue, or
seated on the surface, or like perithecia, as in
Botryosphaeria ribis .In B. ribis there are two
pycnidial forms, a Dothiorella stage containing
very small spores that may function as male cells
and a Macrophoma stage containing larger
spores, one-celled, hyaline, functioning as other
conidia.
Botryosphaeria ribis var. chromogena Current
Cane Blight , Canker , Dieback of currant,
flowering currant, gooseberry, apple, rose, and
many other plants (also Cankers and Die-

backs ) . There are two forms of this species, one
being a saprophyte developing on already dying
tissue. The parasitic form chromogena is so
named from its developing a purple-pink color
when grown on starch paste. There are also
a number of pathogenic strains, varying from
high to low in virulence. Some currant varieties
are quite resistant, but the widely grown Wilder
and Red Lake are rather susceptible.
Dieback and death of fruiting branches occur
as the berries are coloring, with leaves wilting
and fruit shriveling. Later in the season small,
dark, wartlike fruiting bodies appear in rather
definite parallel rows on the diseased canes.
Rose canes show a similar dying back and wilting
above a canker. The fungus winters in the canes;
ascospores infect new shoots; secondary infec-
tion is by spores oozing from pycnidia. The
mycelium grows downward through bark and
wood to the main stem, which it encircles and
kills.
Control Cut out and burn diseased canes as soon
as noticed. Take cuttings from healthy bushes.

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Balansia

Ascomycetes, Hypocreales,
Clavicipitaccae.

Balansia cyperi Diseased Inflorescence , Blight
of purple nutsedge; fungus is systemic and trans-
mitted through tubers.

Beniowskia

Deuteromycetes, Hyphomycetes

Hyphae are coiled at the periphery of mature
sporodochia; spherical spores are borne on short
denticles.
Beniowskia sphaeroidea Blight of knotroot
bristlegrass.

Botryodiplodia

Deuteromycetes, Coelomycetes

Pycnidia black, ostiolate, erumpent, stromatic,
confluent; conidiosphores simple, short; conidia
dark and 2-celled, ovoid to elongate

Botryotinia

Ascomycetes, Helotiales,
Sclerotiniaceae

Botryosphaeria

Stroma a typical black sclerotium, loaf-shaped or
hemispherical, just on or beneath cuticle or epi-
dermis of plant and firmly attached to it;
apothecia cupulate, stalked, brown; ascospores
hyaline, one-celled; conidiophores and conidia
of the Botrytis cinerea type.

Ascomycetes, Dothideales

Asci in locules in a stroma; spores one-celled,
hyaline, eight in an ascus. There is a good deal
of variation in the genus. The locules may be