BIBLIOGRAPHY

RAYMUNDO, LAILANI A. APRIL 2013. Diseases Observed on Different
Cultivars of Cabbage at Harvest Time. Benguet State University, La Trinidad, Benguet.

Adviser: Andres A. Basalong, M.Sc.

ABSTRACT

This study was conducted to determine the disease infecting cabbages in Dada,
Poblacion, Bakun, Benguet and the incidence of diseases in cabbage cultivars.

Diseases observed were black rot (Xanthomonas campestris pv. campestris),
Cercospora spot (Cercospora brassicae), and watery soft rot (Sclerotinia sclerotiorum).
Cercospora leaf spot showed the highest percent incidence followed by black rot and least
was watery soft rot.

Among the six cultivars, evaluated, cultivar “Repolyo” had the lowest incidence of
black rot infection and cultivar “Rareball” for Cercospora leaf spot. Watery soft rot
incidence was very low with no significant effects among the cultivars evaluated.







Diseases Observed on Different Cultivars of Cabbage at Harvest Time |
RAYMUNDO, LAILANI A. APRIL 2013

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RESULTS AND DISCUSSION

Diseases Observed and Symptoms

The diseases observed are block rot caused by Xanthomonas campestris pv.
campestris, leaf spot caused by Cercospora brassicae and watery soft rot caused by
Scleretinia sclerotiorum.
Black rot in the field appeared as yellowish irregular angular spot and brownish at
the inner part of the lesion (Figure 2). Infections appear to start on the leaf margin and
advancing towards the midsections of the leaves. Similarly, Snowdon (1992) reported that
diseased plants from black rot infection turn yellow then brown and dry out.

Infections of Cercospora leaf spot observed in the farm at harvest appeared as
semicircular spot, black with thin yellow halo around the borders of the lesion and sunken
appearance with ash grey center (Figure 3). Symptoms observed were quite similar to
previous report that Cercospora leaf spot are pale grey spots, later turning brown with ash-
gray centers. Subsequently, however, the affected areas became rounded spots, several mm
in diameter and brownish with well-defined borders (Snowdon’s 1992).

Likewise, watery soft rot lesions were observed as water-soaked, black and
brownish at the advancing areas of the lesion and with white mold growth in some parts of
the lesion (Figure 4). Literature cites that initial watery soft rot infections appear as
pinkish-brown and watersoaked; remained firm, but more usually there was a soft
breakdown with much leakage of liquid (Snowdon, 1992).

Diseases Observed on Different Cultivars of Cabbage at Harvest Time |
RAYMUNDO, LAILANI A. APRIL 2013

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Figure 2. Black rot (Xanthomonas campestris) symptom (left) and isolate on nutrient agar
(right)

conidia

Figure
3.
Cercospora
leafspot
Cercospora brassicae (left) and conidia (400x) (right)

mycelia



Figure 4. Sclerotinia (Sclerotinia sclerotium) rot (left) and mycelia (100x) (right)

Diseases Observed on Different Cultivars of Cabbage at Harvest Time |
RAYMUNDO, LAILANI A. APRIL 2013

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Incidence of Black Rot Infection
Black rot infection on cabbage cultivars varied in percent of incidence with lowest
on Repolyo and the highest was Luckyball, but statistical analysis revealed insignificant
differences among the cultivars (Table 1).
Wrapper leaves supposed to be left to serve as protection during transport to market
places were removed and weighed due to infections with black rot. With such premise, the
lowest weight of infected wrapper leaves were from Scorpio and Rareball at 0.125kg and
the highest was from Gladiator at 0.206 kilograms (Table 1). Discarded wrapper leaf from
Gladiator was significantly different to most cultivars except that from Luckyball. With
the condition that wrapper leaves are part of the cabbage head weight at farm gate price,
planter of cultivar Gladiator may be losing an amount supposedly as an income. However
in reference to yield per plot, Gladiator was the highest in yield, owing to it’s
phenotypically larges heads over the other cultivars.

Table 1. Incidence of black rot infection caused by Xanthomonas pv. campestris
CULTIVARS
Incidence

Infected Wrapper
(%)
Leaf (kg)
Scorpio (control)
18.35

0.125a
Rareball
18.88

0.125a
Magicball
18.35

0.163a
Luckyball
21.28

0.194bc
Gladiator
17.52

0.206c
Repolyo
15.41

0.138b
CV (%)
13.57

34.38
Means with the same letters are not significantly different at 5% DMRT.
Diseases Observed on Different Cultivars of Cabbage at Harvest Time |
RAYMUNDO, LAILANI A. APRIL 2013

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Black rot epidemic development is favored by warm wet conditions, therefore low
incidence of infection.

Figure 5. Black rot infection on old leaves (right) and on wrapper leaves (left)

Incidence of Cercospora Leaf Spot and Sclerotinia Rot

Incidence of cercospora leaf spot infection was widespread on the cultivars. The
highest percent incedence of cercospora leaf spot infection was obtain from cultivars
Scorpio at 36.97, followed by Luckyball at 30.15, Gladiator at 28.47, Repolyo at 28.17,
Magicball at 24.34 and the lowest was from Rareball at 23.01 (Table 2). Cercospora leaf
spot infections on Rareball and Magicball are significantly lower than the incidence of
infection on Scorpio.

There was a very low incedence of watery soft rot infection such that some portion
of the blocks did not had infections. There were insignificant defferences among the
cultivars (Table 2).


Diseases Observed on Different Cultivars of Cabbage at Harvest Time |
RAYMUNDO, LAILANI A. APRIL 2013

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Table 2. Incidence of Cercospora leaf spot and Sclerotinia sclerotiorum


Sclerotinia sclerotiorum
TREATMENTS
Cercospora brassicae
(Actual)
(Transformed)
Scorpio (control)
36.97b
0.53
1.02
Rare ball
23.01a
0.80
1.29
Magic ball
24.34a
0.66
1.11
Lucky ball
30.15ab
0.93
1.25
Gladiator
28.47ab
0.80
1.16
Repolyo
28.17ab
0.40
1.09
CV (%)
14.78
85.10
23.95
Means with the same letters are not significantly different at 5% DMRT.


The low incidence of Sclerotinia rot could be attributed to low temperatures within
the cool months ( from November 2012 to February 2013) during the period where cabbage
cultivars were grown. This result conforms with the report of Snowdown (1992) that
Sclerotinia is capable of inducing a watery breakdown of tissues at optimal temperature
for decay being approximately 20oC.

In reference to the percent incidences of each of the pathogens observed,
Cercospora leaf spot appeared to be more predominant than black rot and Scelrotinia rot.
This is attributed the condition of inoculum dispersal, whereby Cercospora leaf spot spores
are wind disseminated than bacterial cells and sclerotium.

Yield Per Plot

Yield per plot showed that Gladiator have the highest yield having the mean of
46.44kg while the lowest yield was Scorpio with a mean of 32.38kg (Table 3).
Diseases Observed on Different Cultivars of Cabbage at Harvest Time |
RAYMUNDO, LAILANI A. APRIL 2013

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Table 3.Mean yield per plot (kg)

CULTIVARS . MARKETABLE

Scorpio (control) 32.38c
Rare ball 46.38a
Magic ball 39.50b
Lucky ball 42.31ab
Gladiator 46.44a
Repolyo 44.25ab
CV (%) 7.82
Means with the same letters are not significantly different at 5% level.

Statistically, the yield of Gladiator and Rareball were significantly higher than the yield of
Scorpio and Magicball, but not to the yields of Luckyball and Repolyo.



Diseases Observed on Different Cultivars of Cabbage at Harvest Time |
RAYMUNDO, LAILANI A. APRIL 2013

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Magic ball Repolyo






Gladiator Rareball






Luckyball Scorpio

Figure 6. Cabbage cultivars



Diseases Observed on Different Cultivars of Cabbage at Harvest Time |
RAYMUNDO, LAILANI A. APRIL 2013

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SUMMARY, CONCLUSIONS AND RECOMMENDATIONS

Summary

The study was conducted at Dada, Poblacion, Bakun, Benguet from November
2012 to February 2013 to determine the incidence of cabbages diseases in Dada, Poblacion,
Bakun, Benguet, the percent incidence of infections to the cabbage cultivars and the most
predominant disease.

Result showed that the disease infecting cabbage cultivars in Dada, Poblacion,
Bakun were black rot (Xanthomonas campestris pv. campestris), Cercospora leaf spot
(Cercospora brassicae), and watery soft rot (Sclerotinia sclerotiorum). Percent incidence
of the pathogens showed that Cercospora leaf spot was predominant based on percent
incidence followed by black rot and least was watery soft rot.
Infections of the diseases observed did not affect the yield as most of the cultivars
were able to produce satisfactory weight of marketable heads per plot.

Conclusions

The disease commonly known as black rot, Cercospora leaf spot and Sclerotinia rot
infects cabbage cultivars in Dada, Publacion, Bakun, Benguet. The predominant disease is
Cercospora leaf spot.

Percent incidence does not provide appropriate measure of disease pressure in
reduction of the cabbage cultivars’ yields. The six cultivars are able to produce marketable
yield per plot as infections of the pathogens were observed to have started later during the
growth of the cabbage plants.
Diseases Observed on Different Cultivars of Cabbage at Harvest Time |
RAYMUNDO, LAILANI A. APRIL 2013

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The infected wrapper leaves entails trimming in the field and the wrapping in place
of the trimmed wrapper leaves with recyclable clean news papers.

Recommendations

As to production per unit area, Gladiator is recommended for cultivation due to
higher marketable yield, owing to larger heads than the other cultivars.
In avoiding Cercospora infection, the predominantly observed disease, cultivars
Rareball and Magicball are preferable for having the low Cercospora leaf spot percent
incidence of infection.
To obtain greater impact of the study, further study shall be conducted during warm
and cold weather condition. Moreover, assessment on the impact of disease from field to
market places shall be done.














Diseases Observed on Different Cultivars of Cabbage at Harvest Time |
RAYMUNDO, LAILANI A. APRIL 2013

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LITERATURE CITED

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DAVIS, W.H. (1925). Drop of Cabbage and our common cabbage by
Sclerotinia sclerotiorum (Lib.) Aylesburg, England. Phytopathology 15, 249-259
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DILLARD, H. R. 1987. Department of Plant Pathology. New York State of Agricuture
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SNOWDON, A. L. 1992. Postharvest Diseases and Disorders of fruits and
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WELLMANN, F. L. 1972. Plant Pathology.Tropical American Plant Diseases. Metuchen
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WILLIAMS, P. H. 1980. Black rot: a continuing threat to world crucifers. Plant
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Diseases Observed on Different Cultivars of Cabbage at Harvest Time |
RAYMUNDO, LAILANI A. APRIL 2013

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