| Summary: | 博士 === 國立臺灣大學 === 植物病蟲害學系 === 86 === The objectives in this study concentrated on the development of methodsfor i
solating and screening most active and effective antagonists, under-standing t
he effects of soil factors on the establisment of antagonists populations in s
oil and formulating organic amendments for increasing the activity of antagoni
sts, as well as the effectiveness of controlling various important plant patho
genis nematodes. The baited tape technique developed in this study provided h
igher capa-bility to isolate the most possible effective nematode-trapping fun
gi, i.e. Arthrobotrys spp., Dactylella spp., Dactylaria spp., and Streptomyces
saraceticus from the soil, than other methods. Baited bag technique was able
to isolate predatory nematodes and mites, especially, compared to soil sprinkl
e baited technique. Streptomyces saraceticus and Pasteuria penetrans decreased
the population of Meloidogyne incognita and control-led root-knot disease of
water spinach in pot tests. Those three nematode-trapping fungi had significan
tly (P=0.05) less capability than S. sarace-ticus to control M. incognita on w
ater spinach, Mononchus sp. was unable to control M. incognita. Since P. penet
rans was difficult to be propagated in laboratory, S. saraceticus had been int
erestingly used. S. saraceticus developed well in loamy sand, sandy loam and
red soil at the pH value from 5 to 8. The number of egg mass on the roots of w
ater spinach and juveniles of M. incognita present in soil were lower than the
control when S. saraceticus alone or mixed with 0.2% crab shell powder to be
incorporated in the soil. Consequently, the fresh weight of above-ground tissu
es of water spinachwas increased. Besides M. incognita, S. saraceticus was ab
le to reduced significantly (P=0.05)the infection and populations of Tylenchul
us semipenetrans, Praty-lenchus coffeae and Paratylenchus curvitatus in green
house trials. Among 14 tested organic wastes, crab shell powder, soybean powd
er, castor pomace, marine algae powder, rice bran or molasses amended in the s
oil was able to increase the population of S. saraceticus. The by products dec
omposed from saw dust, rice bran and pig dung could cause paralysis of juven
iles of M. incognita, while castor pomace, chicken dung and crab shell powder
were toxic to the nematodes lethally. Hatching rates of egg masses or disperse
d eggs were inhibited only by castor pomace among these tested organic materia
ls. The amendment of marine algae powder made the roots of host plant reduce a
ttraction to juveniles of M. incognita for 36.0%, T. semipenetrans for 30.1%,
P. coffeae for 44.0% and Pa. curvitatus for 35.0%. Based on the effectiveness
of controlling tested nematodes, the mixtures of 40% crab shell powder, 40% ca
stor pomace, 5% soybean powder, 10% marine algae powder and 5% molasses was fo
rmulated and named Lively Tiller Mixture (LT-M). LT-M, applied at the rate of
2000 kg/ha, decreased signifi-cantly (P=0.05) The root-knot indices and diseas
e indices for 47.5, 67.8 and 42.8, 69.5% at summer and winter harvest, respect
ively, compared to untreated control. Besides, LT-M also increased cluster wei
ght and sugar content to 57, 76 grams and 3, 5 Brix。at the two harvest season
s, respec-tively. Antinematodal properties were enhanced when LT-M was applied
for 2 years continuously. Application of LT-M on controlling T. semipenetrans
was as good as nematicides, but LT-M provided more vigorous growth among the
declined citrus plants compared to nematicides. LT-M in soil reduced the popul
ation of T. semipenetrans and P. coffeae 94.1 and 63.6﹪ respectively, compare
d to the control. Application of LT-M again significantly (P=0.05) controlled
root-knot disease on African dasily and bitter gourd compared to 3﹪ carbofura
G. The antinematodal principles were not presence in he tested plants.
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