Biology Reference
In-Depth Information
treatment with chemicals. Most chemicals are
meant for fallow soil; a few are safe around living
plants. Details of nematicides and their applica-
tion are given in chapter
for 1 year. Soak seed for 2 h in tepid water with
a wetting agent; then hold for 15 min at 126
F.
Anguina balsamophila On balsam-root; galls
on underside of leaves.
Anguina graminis Galls on leaves of fescue
grasses.
Anguina tritici
Wheat Nematode
on wheat and
rye, a field crop pest forming galls in place of
grain. The disease was recognized in 1745, the
first to be attributed to nematodes. The species is
long-lived, viable nematodes having been found
in seed stored 28 years. Brine flotation was the
old method of eliminating galled seed.
Introduction.
Greenhouse soils are often steam-sterilized, and
plants are sometimes dipped in hot water, the
duration of the soak and the temperature
depending on the tolerance of the plant and the
kind of nematode to be eradicated. Some plants
are antagonistic to nematodes. Asparagus roots
produce a chemical that is toxic to many species,
and marigolds grown with or in advance of some
flower crops reduce the numbers of
Pratylenchus
,
lesion nematodes. Some soil fungi trap
nematodes but do not provide a practical control.
The endospore-forming bacterium
Pasteuria
penetrans
is known to effectively suppress
certain root-knot nematodes.
▶
Aphelenchoides
Aphelenchoididae. Bud and leaf nematodes,
foliar nematodes. Ecto- and endoparasites;
males and females wormlike, very slender; cuti-
cle finely annulated; stylet with small basal
knobs; tail with acute tip.
Aphelenchoides besseyi (including
A. oryzae
).
Summer Dwarf Nematode
of strawberry, pre-
sent from Maryland to Louisiana, also reported
from Oklahoma, Missouri, southern Illinois, Cal-
ifornia, and Washington. The nematodes live in
the soil and are washed into buds by rains and
irrigation water, affecting young leaves as they
develop. Leaflets are crimped or crinkled,
cupped, narrow, with a reddish cast to veins and
petioles. Older leaves are darker green, more
brittle than normal. This is a major disease in
Florida, commonly noted from July to October.
Cold weather checks its progress often masking
symptoms, but plants do not recover; runner
plants from infested mother plants are diseased.
In spring the nematode population may be low,
allowing nearly normal formation of early leaves,
but in summer a single bud may harbor up to 1300
individuals, causing center leaves to be deformed
and dwarfed. The same species causes a serious
disease of rice in Arkansas and Louisiana.
Control
Buy certified plants; rogue and burn dis-
eased plants as soon as noticed. Treat dormant
infested plants with hot water, 2 min at 127
F.
Aphelenchoides
Anguina
Anguinidae. Endoparasitic nematodes feeding in
above ground plant tissue and transforming seeds
or leaves into galls. Males and females both elon-
gate (wormlike), but females are obese. Cuticle
finely striated; stylet short with well-developed
basal knobs; tail coneshaped; single ovary.
Anguina agrostis
Grass Nematode
, serious on
bent grass and chewings fescue in the Pacific
Northwest. Second-stage larvae remain in
sheaths near growing tips most of the year, enter-
ing embryonic flowers in late spring. There the
larvae mature, and the females lay large quanti-
ties of eggs. The quickly hatching young larvae
transform developing seed into elongated dark
purple galls. When the galls fall to the ground,
nematodes are released to reinfect grass in the
vicinity. There is only one generation a year,
and larvae cannot exist in moist soil more than
a year without access to a host plant with devel-
oping inflorescence. The disease is important
only on grass grown for seed; it is not a problem
on clipped turf. When seed is threshed, galls can
be carried 300 feet or more from the machines by
air currents, and still further in heavy winds.
Control
Rotate with a crop other than bentgrass
or fescue or plow under and prevent inflorescence
fragariae (including
A.
olesistus
).
Spring
Dwarf
Nematode
of
