|
|
Home
> Plant
Diseases
>
Genus Ditylenchus Filipjev
>
DitylenchbS angustus (Butler, 1913) Filipjev,
1936, The Rice Ufra Nematode
DitylenchbS
angustus (Butler, 1913) Filipjev, 1936, The Rice Ufra Nematode
It is a
parasite of rice plants and the disease caused by it is known as 'Ufra'.
It is aJso known as the rice stem nematode. It was first reported in
I91383 from areas now forming the territory of Bangladesh,
The disease was found to be quite prevalent in the areas of flooded
paddy cultivation. At that time about 6 million acres of paddy fields
were reported to be infected by the nematode.
|
Morphology
Compared to
D, dipsaci, D, angustus is slightly slender nematode with low
and fattened lip region. Tail possesses a sharply pointed tip.
Biology
The
nematode follows an ectoparasitic mode of life and can be-found at
the peduncle base, the stem just above the upper nodes or inside the
panicle glumes. At harvest, the nematode present in the tissues,
becomes inactive and in coiled stage. These cottony
masses of
quiescent nematodes remain in the stubble and infect the crop in the
next growing season. The nematodes climb up the stem, in humid
conditions, and attack the stems, leaves and invade the growing
point. The infloresence is invaded also which may result in failure
in formation of grain heads or if formed, these may contain only
few shrivelled grains. At the heading stage, nematodes collect
between the inner side of leaf sheath and the developing ear for
feeding.
|
|
Branching of
stem or even development of 3 to 4 distorted ears inside a single
boot leaf sheath may occur also Nematodes in the quiescent stage (wool
stage) can remain in a desiccated condition for over 6 months and the
spread is mainly through seedlings, irrigation water and farm
implements.
Symptoms
The earliest
symptom of damage in fields is chlorosis of upper leaves. Two distinct
categories of symptoms, swollen 'ufra' and ripe 'ufra', have been
recorded. In the former case, the panicle remains enclosed within the
leaf sheath with the infected portions leading to branch. In the ripe 'ufra'
case, the panicle emerges and produces normal grains only near the tip.
In the netnatode infested plants, the peduncle becomes dark brown with
flowers, in the lower part, remaining unfertilized. In few cases, the
panicle emerges partially.
Control
Destruction of
infested stubbles followed by plougbings to keep fields dry for 2 to 3
months helps in destruction of the nematode, In the standing crop,
spraying diazinon (100 ppm) copiously on the foliage and soil may help
in reducing nematode populations. Application of phorate at 40 kg/ha to
soil may also help in minimizing plant damage87.
|
