|Studies on Fusarium Wilt of Spinach
@The outbreak of soil-borne diseases inflicts economic damage on spinach
cropping. In this study, the incidence of soil-borne diseases of spinach
was surveyed at major cropping areas in Iwate prefecture. It was revealed
that Fusarium wilt of spinach, caused by Fusarium oxysporum f. sp. spinaciae, has been the most serious disease. Based on these results, distinctive
incidence of Fusarium wilt among cropping areas was analyzed by comparing
the isolation rate of pathogenic fungi and distribution of vegetative compatibility
groups with nitrate non-utilizing (nit) mutants. Finally, control methods were researched without chemical fungicides.
Results obtained were as follows.
1. Surveys of incidence of soil-borne diseases of spinach at major cropping areas in Iwate prefecture
@At major cropping areas such as Tono, Nishine and Yamagata, outbreaks
of soil-borne diseases of spinach were observed from June to September
at the harvesting periods, that is, Fusarium wilt, root rot, damping-off
and foot rot. The incidence of outbreaks distinguished the areas as follows.
In Tono, incidence of Fusarium wilt and root rot disease was recognized.
In Nishine, incidence of root rot disease was mainly recognized, and Fusarium
wilt was also observed. And in Yamagata, although incidence of soil-borne
disease was not abundant, incidence of Fusarium wilt was observed. Damping-off
was not abundant and foot rot was hardly observed. The relationships between
these distinctive incidence and soil-type, or continuous cropping years
were not founded. However, Fusarium wilt disease was most important for
spinach cropping because the outbreak of this disease has been observed
in different many areas.
2. Establishment of the methods for pathogenicity test of Fusarium oxysporum isolated from wilted spinach
@The methods for the pathogenicity test of F. oxysporum isolated from spinach were studied. The inoculated density to soil for disease incidence was 102 colony forming units / g of soil (cfu), and 104 cfu was needed for disease development. In this case, the disease development
using a budcell suspension for inoculum was used as well as using conidia
in infested soil. The most susceptible growth period of spinach for pathogenic
fungi was at the emergence-cotyledon period, and then disease severity
was higher than inoculation at the sowing period or after 2 - 4 leaves
had developed. The most sensitive spinach cultivars were cv. 'Okame', 'Magic'
and 'Oracle', because these varieties wilted without differences in severity
against all tested pathogenic isolates. The next method of pathogenicity
test was simple and was suited to test many isolates isolated from wilted
spinach as follows. Spinach seedlings were grown to the emergence-cotyledon
period in a nursery on a plug tray (128 cells, using mixed soil for plug
seedlings), and then were drenched evenly with budcells suspension (107 - 108 budcells/ml). After 2 - 3 weeks, the pathogenicity of isolates were assessed
with the simple disease rating that surveyed them on the whole of the treatment.
The isolation rates of pathogenic F. oxysporum obtained from wilted spinach in major cropping areas were investigated
with the above pathogenicity test. It was found that the isolation rate
was high in Tono (91.7%) and Yamagata (69.0%), but the rate was low in
Nishine (45.3%), a result that approximately agreed with survey incidence
of fusarium wilt at major spinach dropping areas.
3. Distribution of vegetative compatibility groups of Fusarium oxysporum recovered from wilted spinach
@Geographic distribution and population structure of mono-cultured spinach of Japanese isolates of F. oxysporum f.sp. spinaciae in Japan and Iwate prefecture were studied on the basis of vegetative
compatibility groups (VCGs) with nit mutants and pathogenicity tests. VCG0330 and 0331 are distributed widely in Japan. Although, VCG0332 was detected only in one prefecture from which many isolates were tested, VCG0332 must also be present in other prefectures because VCG0332 is distributed widely in Iwate prefecture. In every case@such as in Japan, Iwate, major cropping areas and a field, VCG0330 existed preferentially and VCG0331 and 0332 were minor groups. In the field, isolates of F. oxysporum f. sp. spinaciae had diversity with one major VCG and other minor groups. Seasonable variation
of VCGs composition in Iwate prefecture was found. Although the composition
rate of minor groups, VCG0331 and 0332, had reached a peak in summer cropping,
these isolates could not be detected in autumn cropping. On the other hand,
the rate of the major group VCG0330 gradually became higher as continuous
cropping was increased. VCG0330 may be easy to spread with the above condition.
Optimum growth temperatures of standard isolates of 3 VCGs were equal at
20 - 30. Pathogenic isolates which were not compatible with the three
pathogenic VCGs nor with pathogenic isolates were found widely in Iwate
4. Evaluation of spinach cultivars for resistance to Fusarium wilt disease applying pathogenicity test
@The established method for the pathogenicity test of F. oxysporum isolated from wilted spinach was applied to the evaluation of spinach
cultivars for resistance to Fusarium wilt. The differentiation of variety
resistance was observed with the inoculation method with the following
conditions. Inoculum density was prepared at 105 - 106 budcells/ml, and then the seedlings were inoculated with isolates using a repeating syringe. Resistance was classified into 5 levels by a frequency distribution with an average disease index of 25 cultivars, inoculated with 5 isolates of pathogenic fungi, respectively. Comparative cultivars were decided at respective resistant levels for relative evaluations and were as follows. 'Highly resistant': 'Ujo' ; 'Lightly resistant': 'Atras' or 'Solomone' ; 'Intermediate': 'Baltic' and 'Active' ; 'Slightly susceptible': 'Munsterland' and 'Okame' ; 'Highly susceptible': 'King of Denmark' and 'Magic'. The host-pathogen interaction was statistically significant at the 1% level on the analysis of variance in disease severity. However, the interactive variance ratio was small in comparison with variations in fungal virulence and host resistance.
5. Control methods of Fusarium wilt of spinach
 Biological control of Fusarium wilt of spinach with non-pathogenic
@Many isolates of F. oxysporum were recovered from spinach grown in the field infested with Fusarium
wilt pathogen. Non-pathogenic strains were included in these isolates.
Non-pathogenic F. oxysporum isolates S3HO3, S1HI1-w, 970211, 970481, 970576 and 970600 showed cross-protection against F. oxysporum f. sp. spinaciae when isolates were inoculated by soil-application before infestation with
the pathogen. F. oxysporum isolate S3HO3 was mainly used for development of control methods. Non-pathogenic
F. oxysporum isolate must be inoculated into soil before infestation with pathogenic fungi. An inoculum density of more than 104 bud-cells / g of soil and 10 - 100 times the pathogen inoculum density was required for the soil-application of bud-cell suspension. This cross-protection, however, did not continue through the harvesting. In order to extend the duration of disease suppression, pre-treatment of spinach seedlings with non-pathogenic F. oxysporum S3HO3 was combined with subsequent transplanting to reduce disease development.
The most effective pre-treatment method for seedlings was mixing a bud-cell
suspension (106 cfu/dry@soil g)@with nursery soil before sowing and then growing seedlings
for 15 days before transplanting. Disease suppression then lasted through
harvesting with a high protective value when pre-treated seedlings were
transplanted in infested soil. Non-pathogenic F. oxysporum S3HO3 was not pathogenic for spinach and many other vegetable crops. A practical control test of Fusarium wilt of spinach by transplanting seedlings pre-treated with non-pathogenic F. oxysporum was assessed in the natural infested field. The protective effect of this
method was even greater than that obtained by direct sowing, and more effective
than transplanting without non-pathogenic F. oxysporum. And that was as effective as solar heating sterilization in a closed
green plastic house in summer. The protective effect lasted through harvesting.
These results suggest that control of Fusarium wilt of spinach by transplanting
culture with non-pathogenic F. oxysporum should be practical. In addition, non-pathogenic F. oxysporum was able to suppress not only Fusarium wilt but also Pythium damping-off
on spinach and other pathogenic fusaria of cucumber, melon, watermelon,
radish and garland chrysanthemum when non-pathogenic F. oxysporum was added to the soil before inoculation of respective plant pathogens.
Furthermore, the mechanisms of disease suppression by non-pathogenic F. oxysporum were studied. The mechanical plugging of wounds with bud-cell pellets of non-pathogenic F. oxysporum induced the cross-protection in spinach plants. The culture broth filtered
with a 0.45Κm mesh membrane filter had the ability to inhibit pathogen
growth, such as the inhibition of conidia germination or the elongation
of germtubes. Finally, the result of the prosperity and decay of both densities
of non-pathogenic F. oxysporum and pathogen in root tissue suggests that competition with each fungus
has appeared in spinach root tissue. This is because colony formation of
non-pathogenic F. oxysporum recovered from healthy spinach root tissue was more than that of pathogen, but colony formation of non-pathogenic F. oxysporum recovered from diseased root tissue was less than that of pathogen. In
addition, the detected period of pathogen from root tissue inoculated with
non-pathogenic F. oxysporum was later than the one without non-pathogenic F. oxysporum. These result suggest that competition has appeared in spinach root between non-pathogenic F. oxysporum and pathogenic F. oxysporum.
 Control of Fusarium wilt of spinach by solar heating sterilization in the closed plastic house
@In Iwate prefecture, solar heating sterilization has not succeeded before.
The reason for this failure was considered to be the difficult of raising
the soil temperature. In order to address this problem, mulching plus plastic
film used to raise the effective soil temperature@(40 at depth of 10cm),
and no cultivation after sterilization to avoid confusion of sterilized
soil and non sterilized soil, were studied in the naturally infested field.
Solar heated sterilization was applied from June 26 to July 25 and there
were 131 hours of the effective soil temperature. High protective effect
was observed for this treatment before summer harvesting. The daily hours
of the effective soil temperature correlated with the sunshine duration
time of the meteorological observation point in Tono (AMeDAS observation
point). The above result suggests that solar heating sterilization is also
a practical control method during June and July in Iwate prefecture.
 Effect and durability of disease suppression of Fusarium wilt of spinach by soil-application with composted chitin materials
@Composted crab shells were used for suppression of Fusarium wilt of spinach
in this study. In pot level and the field level studies, disease suppression
with soil application of this material after soil sterilization has been
higher than without soil sterilization and with no application. In another
field, the applying condition was studied. The most effective disease suppression
was observed through harvesting when the composted crab shell material
has been applied to soil every year. The soil sterilization was treated
in the first year, but has not been needed after the next year. An increase
in disease was observed in the no application year when an alternative
year application system was used. These results suggest that composted
crab shells must be applied to the soil every year to suppress Fusarium
wilt of spinach in a field.
|The Breeding Process and Characteristics of Five New Clonal Lines "Ai
Star" of Limonium sinuatum Mill
|Toshiichi Takahashi, Zenbi Naitoh, Hiroshi Satoh and Tatsuo Yoshida
@With the purpose of breeding new high quality Limonium sinuatum,@"Sopia" was selectively cultivated as breeding material. Individual
selections were carried out from 1995 to 1997, the characteristics of sixteen
chosen clones were researched from 1996 to 1998, and the superior lines
were selected. After five of the "Ai Star" clonal lines were
checked and confirmed for stability, they were given identification numbers
in 1998 and were entered to be officially registered the following year,
1999. The clonal lines were found to be suitable for cropping in the spring
and summer, autumn and winter, deferment of autumn and winter. The
characteristics of each of these clonal lines are as follows. "Ai
Star Rosy Pink" has a sepal color of bright red purple and has a high
output of quality flowers. It has a long sepal diameter as well as a long
flower spike length, and therefore seems to be of generally larger volume
than the other types. "Ai Star Lilac" has a light purple sepal
color and a small stem wing. The sepal diameter is of medium size and the
number of produced flowers is large. The flower spike form seems to be
good for various cropping types. The sepal color for "Ai Star Lilac
Blue" is light purple and has a good output of quality flowers. It
has a long sepal diameter as well as a long flower spike and good volume.
The sepal color of "Ai Star Lavender" is light purple and the
tip of the sepal is a bright bluish purple. The stem wing is small. The
flower spike is wide and the form is suitable for various cropping types.
The sepal color of "Ai Star Mauve" is a vivid red purple. The
branch length and the flower spike length are medium, and the flower spikes
are good for various cropping types. As for a low temperature requirement
for bolting in "Ai Star Rosy Pink", it was found a 50 to 60 day
period at 15, and to induce high bolting rate, and to yield the largest
crop. The rooting rate in response to cutting propagation was found to
differ between the lines, but even in the more difficult lines, a high
rooting rate was produced with the use of a chemical rooting agent. For
"Ai Star Lilac" and "Ai Star Lilac Blue", autumn and
winter cropping types which used rooted herbaceous cutting, crops were
produced by raising the seedlings naturally.
|Breeding of a New Green Soybean Variety,"Takikei-C8 (named "Chage-maru")"
|Takuya TAKAHASHI, Kazuo SAKUYAMA, Yuichi IMURA, Yutaka KIUCHI, Kazuya OIKAWA, Tsutomu SASAKI, Yoshinori KAMIYAMA, Masashi NITTA, Hisashi KOWATA, Yoshiaki OHGI and Hiroshi ISHIKAWA
A new green soybean variety "Takikei-C8(named "Chage-maru")" was developed from a cross between "Fukura", which is good-taste, medium-maturing and the central variety in Iwate, and "Chusei-chamame", which is good-taste and late-maturing, at the Iwate Prefectural Agricultural Experiment Station in 1986, for the purpose of breeding of a good-taste, well-yield and medium-maturing green soybean.
@"Takikei-C8" belongs to the medium maturity group that is later
than "Fukura" about 5 days, and if it is sowed between the middle
and the late in May, it is able to harvest between the middle and the late
in August at the middle and the south region in Iwate. The sum of shells
is more than "Fukura", and it is very well-yield among medium-maturing
green soybeans. And, again, the rate of complete shells and the rate of
shells that possess more than 2 grains are high. And furthermore, it's
sweetness and smell are very good, which are better than "Fukura"'s.
|Breeding of a New Green Soybean Variety,"Takikei-C11 (named "Pukkurako")"
|Takuya TAKAHASHI, Kazuo SAKUYAMA, Yuichi IMURA, Yutaka KIUCHI, Kazuya OIKAWA,
Tsutomu SASAKI, Yoshinori KAMIYAMA, Masashi NITTA, Hisashi KOWATA, Yoshiaki
OHGI and Hiroshi ISHIKAWA
A new green soybean variety "Takikei-C11(named "Pukkurako")"
was developed from a cross between "Fukura", which is good-taste,
medium-maturing and the central variety in Iwate, and "Kinshu",
which have large-shells and which is well-yield and late-maturing, at the
Iwate Prefectural Agricultural Experiment Station in 1986, for the purpose
of breeding of a having large and good-appearance shells and medium-maturing,
whose harvesting season is the 4th~5th five days of August at the middle
and the south region in Iwate, green soybean.
@"Takikei-C11" belongs to the medium maturity group that is
later than "Fukura" about 8 days, and if it is sowed between
the middle and the late in May, it is able to harvest between the middle
and the late in August at the middle and the south region in Iwate. The
rate of complete shells and the rate of shells that possess more than 2
grains are high. And, again, its appearance quality is good, because it's
shells is large and deep green. And furthermore, it is good-taste.
|Breeding of a New Rice Variety "Gin-otome" Suitable for Sake
|Hitoshi HATAKEYAMA, Hiromi SUGAWARA, Tsutomu SASAKI, Hiroya ODANAKA, Shinsuke
NAKAJYO, Masahiro TAKAHASHI, Nobuo TAKAHASHI, Syoji URUSHIBARA, Hisashi
KOWATA, Yoshiaki OHGI, Hiroko NAKANO, Akikazu NAKANISHI and Tsuyoshi UWANO
|@A new rice variety "Gin-otome", suitable for sake brewing,
was developed from a cross between "Akita-Sake 44" and "Tohoku
141(named "Kokoromachi")" at the ex-Iwate Agricultural Experiment
Station (the current Iwate Agricultural Research Center) in 1990.
@This variety was developed with intent of breeding an early-maturing
variety for sake brewing.
@Breeding was conducted using the "bulk method" in its early
generations. After individual selection in F4, line selections, performance test and tests of specific character were
@After line selections of F5, evaluation of the suitability for sake brewing was conducted by Iwate
Industrial Research Institute. As the results, "Iwate-Sake52"
was selected from the F7 lines. In F8, the test brewing was conducted by Iwate Sake Brewing Association. "Iwate-Sake
52" was released in Iwate prefecture as a recommended variety suitable
for sake brewing and named "Gin-otome" in 2000. The major characteristics
of "Gin-otome" are as follows.
||It belongs to the early maturing group, and its date of heading and maturity
are same as or slightly earlier than that of "Takaneminori".
||It is partial panicle plant type. Its culm is shorter and panicle number
is fewer than "Takaneminori".
||The lodging resistance is slightly inferior to "Takaneminori", superior to "Miyamanishiki".
It seems to have true resistance genes of Pi a, i. The field resistance for leaf and panicle blast is both higher than "Miyamanishiki".
||It has moderate tolerance to sterility caused by low temperature before heading.
||The yielding ability is less than "Takaneminori".
||The quality of grain is slightly lower than "Miyamanisiki".
||The wight of 1000 grains is heavier than "Miyamanishiki".
The suitability for sake brewing of "Gin-otome" is equal to "Miyamanishiki"
judging from the results of examination that was conducted by Iwate Industrial
Research Institute and Iwate Sake Brewing Association.
|Early and Easy Diagnostic Methods and Control of Apple Violet Root Rot
Caused by Helicobasidium mompa Tanaka in Dwarfed Apple Trees
|Fusaharu NAKATANI, Giichi ANDOH and Satoru TAKAHASHI
|@Pannose mycelial mat of violet root fungus forms in and around the base
of dwarf apple trees, which at first appear to be healthy, but which decline
after a few years. This can then spread along a row of apple trees. Purple
spots appear on the leaves of the "Fuji" apple tree, when affected
by violet root rot, in summer and autumn and the spots are in proportion
to the severity of the disease. In the case of the "Tsugaru",
many of the buds become deformed and die, which is a new symptom, similar
to that of valsa cancer, observed after acute defoliation in summer. Effective
fungicides have been screened through injecting solution into the roots
of the apple trees that had developed mycelial mats the previous autumn.
The success of these control measures was examined by comparing mycelial
mats forming on the trunks of dwarf roots in the autumn of the year when
the fungicides were injected. As for the baiting method of H. Monpa from
the soil, inserting into the branch was found to be more effective than
the busying method, and this was used for the evaluation of fungicides'
evaluation too. After screening, tolclofos-metyl solution (40 liters/tree)
into the soil (at a depth of 0-30cms) within a radius of 1m2 in the spring could prevent the reoccurrence of new mycelial mats in the
autumn and the development of the disease. The trees made a remarkable
recovery from the damage and produced the same amount of fruit as the healthy
trees. Applying composed chitin materials (Neoappu: 7.5kg/tree) after removing
the root soil from the trees in spring, could prevent the formation of
mycelial mat a little, but the combined treatment of amobam solution could
prevent the formation of mycelial mat in autumn and the development of
the disease. As a result of this the trees recovered.
|Effect of Growth on Weight of Seeds in Cabbage
|Fumihiro KANNO, Katsuo KODAMA and Hidenori SUGAWARA
|@Weight of cabbages seeds has nearly normal distribution. The light seed
and heavy seed are brought up to a big set and a small set, respectively.
The lighter seed growth is not uniform. A deference of the growth affects
it's a taking root. The deference remains after planting at a field. Therefore,
we need to make uniform weight of the seed for a uniformity culture of
cabbage. Additionally, we should remove small seeds, because it's include
a lot of un-mature seeds that tend to growth un-uniformly because of weak
germination of the seed.