Proceedings of 7
th
 International Symposium, SEUSL, 7
th
 & 8
th
 December 2017 
 
239 
 
EFFECT OF MYCOHERBICIDES ON WATERHYACINTH 
[EICHHORNIA crassipes MART. SOLMS]  
 
M.I.S Safeena1* and A. Cheanieha Queene1,  
1Department of Biological Sciences, Faculty of Applied Sciences, South 
Eastern University of Sri Lanka, Sammanthurai, Sri Lanka 
 
safeenim@seu.ac.lk   
 
ABSTRACT: One of the major problem accompanying water resource development in 
Sri Lanka is the explosive proliferation of water hyacinths (Eichhornia crassipes). A 
survey of plant pathogenic fungi associated with naturally infected water hyacinth was 
conducted in different waterways in the Eastern part of Sri Lanka and potential 
isolates including Alternaria alternata, Cercospora rodmanii, Aspergillus sp.and 
Trichoderma sp. were identified. The four identified fungi were evaluated for their 
pathogenicity on water hyacinth at laboratory conditions. The first pathogenicity trial 
indicates, the leaf area affected by the fungal pathogen changes with the intensity 
(days). The changes in leaf area affected by the pathogen across intensity levels 
depend upon inoculation method (p=0.003). But there was no statistically significant 
effect in the inoculation methods on the leaf area affected by the fungal type (p=0.06).  
All fungal types had different levels of dead lesions formed in water hyacinth. After 
seven days of inoculation, Alternaria sp. revealed to have the highest affected area, 
followed by Aspergillus sp. and Cercospora sp. but, all four fungal species had similar 
level of effects in term of dead lesion formed in leaves after 22 days of inoculation. 
During the confirmation test, observed diseased symptoms also similar to first 
laboratory trial which confirmed that the disease syndromes of first lab trial were 
caused by the inoculated pathogenic fungi, not from the other factors and also indicate 
that, after one week of inoculation A.alternata revealed to have the higher affected 
area  followed by C rodmanii and Aspergillus sp. and the Trichoderma sp. did not give 
a significant effect on confirmation test. The selected three pathogenic fungi including 
Alternaria sp., Aspergillus sp., and Cercospora sp.  can easily culture and disease can 
cause by conidia, mycelial fragment or mycoherbicidal preparation. Different carriers 
produced different levels of affected leaf area upon infection by the fungal type 
(p<0.0001). However, fungal types alone did not show differences in the formation of 
dead lesions in the leaf surfaces of water hyacinth (p=0.31). Moreover, the carrier type 
and fungi do not combine to influence the overall area affected by the fungus (p=0.49). 
A better and quick infection caused by the mycoherbicidal preparation with oven ash. 
The extent of infection depends on the concentration of mycoherbicide and the 60% of 
oven ash concentration showed better result on water hyacinth control. We concluded 
that, A. alternata and Cercospora rodmanii could be used as effective biocontrol 
agents against water hyacinth following performance evaluation under natural 
environmental conditions and their host specificity test. 
Keywords: Water hyacinth, Pathogenic fungi, Bio control, mycoherbicide 
 
1.INTRODUCTION 
Aquatic ecosystems throughout the world are threatened by the presence of 
invasive aquatic plants, both in the form of floating and submerged. Sri Lanka 
is an agricultural country with a population of 21 million people. Majority of the 
farming community relies on irrigation water to raise successful crops as the 
country experiences periodic droughts during cropping season (FAO's Plant 
Production and Protection Division-AGP, 2016). The productivity of inland 
water bodies in the country is affected by the excessive growth of aquatic 
weeds, such as floating, submerged and rooting emerged species. A recent 
conducted survey of plant production and protection division of Sri Lanka 
Proceedings of 7
th
 International Symposium, SEUSL, 7
th
 & 8
th
 December 2017 
 
240 
 
showed that 45% water bodies are infested with water hyacinth. In Sri Lanka, 
it has been intentionally introduced for ornamental purpose in 1904 and later it 
was widely distributed despite its declaration as a prohibited weed under 
Water Hyacinth Act in 1909 and subsequently under Plant Protection Act in 
1924. 
The main approach for the control of aquatic weeds in Sri Lanka has been 
traditional biological control, which has been practiced from early fifties. Initial 
attempts made on controlling aquatic weeds followed mechanical approach 
supplemented with chemical control (Harry C Evans, 1999). However, all 
these methods failed to provide long lasting effects due to rapid multiplication 
of the weeds and the relatively low efficacy of control methods.  
In recent years, attention has centered on biological control, which could 
provide a cost-effective environmentally safe, solution to the water hyacinth 
problem (Charudattan, R. and Dinoor, A. et al., 2000) and most emphasis has 
been given to fungal pathogens as biocontrol agents (Vincent, 2001). 
So, this study’s objective was to identify and evaluate potential pathogens 
associated with water hyacinth to use as biocontrol agents in laboratory 
conditions. 
 
2.METHODOLOGY 
The laboratory trials were carried out during 2016 at Department of biological 
science, Faculty of Applied Sciences, South Eastern University of Sri Lanka to 
evaluate the pathogenicity of selected fungi to control the water hyacinth. 
2.1 Surveying diseased water hyacinth 
A survey was conducted to document various fungal pathogens of 
waterhyacinth in the water bodies of Batticaloa and Ampara districts of Sri 
Lanka. In each district, five locations were surveyed and plants that developed 
symptoms like leaf spots, lesions, blights, chlorosis, rots and browning were 
collected. 
2.2 Sampling procedure, isolation, and fungal identification 
Samples were transported to the laboratory in clean plastic bags and stored at 
4° C until examined. Stored plant parts were scrubbed under running water to 
remove surface debris, dissected into small segments (approximately 1 × 1 
cm), and surface-sterilized by sequential immersion in 96% ethanol for 30 S, 
14% hypochlorite for 30 S, and then rinsed with sterile water for 1 min. 
Surface sterilized segments (4 segments per plate) were placed on potato 
dextrose agar (PDA). Twenty plates were used for petioles and leaves and the 
plates were incubated for 5 to 7 days. Fungi that were developed on the plant 
pieces were isolated, and pure cultures were obtained by the single-spore or 
hyphal-tip technique, depending on the type of fungal isolate. Identification of 
the different fungal genera was based on morphological characteristics of 
each growing microbial colony. 
2.3 Pathogenicity tests 
Healthy water hyacinth plants were collected from natural water bodies and 
they were grown with hydroponics method in lab with suitable environmental 
conditions. Pathogenicity test for fungal species was performed by preparing 
Proceedings of 7
th
 International Symposium, SEUSL, 7
th
 & 8
th
 December 2017 
 
241 
 
the spore suspension from each isolate by adding 15 ml water. The 
suspensions were centrifuged at 3000ppm for 5mins and the supernatant was 
removed. Finally, 250ml of fungal suspensions were prepared with sterile 
water. The number of fungal spores was adjusted under microscope using a 
dilution series. Young leaves of some water hyacinth plants were rubbed with 
carborundum powder for facilitating penetration of spores, and then the leaves 
were washed-off with sterile distilled water (Firehun et al., 2006). Fungal 
suspensions were sprayed to the healthy plants using low-pressure hand 
sprayer then the plants were covered with polythene bags to avoid 
unnecessary spore drift to the next treatment and to maintain the RH. After 
inoculation, the four treatments along with the non-inoculated control plants 
were arranged in randomized complete block design (RCBD) with four 
replications each. The treated plants were observed for the appearance of 
disease symptoms and the infected leaf area was measured from 2 to 22 days 
after inoculation. 
2.4 Confirmation tests of pathogenicity 
The diseased leaves of pathogenicity tests were collected for each treatment. 
Associated fungi on the collected leaves were isolated and pure cultures were 
prepared. The isolated fungi from the confirmation test were inoculated to 
young healthy plants which are grown hydroponically and the inoculated 
plants were incubated for 5 days. After inoculation, the diseased symptoms 
that were appeared in the pathogenicity test were confirmed and infected area 
of leaves was measured from 2 to 7 days. 
2.5 Formulation of the pathogenic fungi for application as 
mycoherbicides 
Isolates of 3 selected pathogenic fungi were grown in 250ml Erlenmeyer 
flasks, each containing 100ml of potato dextrose broth. The PH was adjusted 
to 8 after treatment with sterile 1N NaOH. After incubating the cultures at 25° 
C for 3 weeks, mycelial mats were filtered for each isolates. The fungal 
preparations were obtained by air – dried (48 hrs.) and ground by motor and 
pestle to get fine powder. Corn flour and oven ash were added to each 
treatment (30% and 60% w/w concentrations). Two replicates were conducted 
of each treatment and the control treatment was maintained with no additives 
and fungi. Treatments were water hyacinth controls, and plants were sprayed 
with; a fresh suspension of fungal spores and mycelium fragments; corn flour 
suspension; oven ash suspension; a mixture of corn flour and oven ash. One 
–half of each formulation was added to 20 ml of sterile water and sprayed on 
healthy water hyacinth plants at the 3-4 leaf stage. Treated plants were 
covered with polythene bags for 5-10 days after inoculation. Finally, the 
infected areas of the diseased leaves were determined from 2 to 14 days. 
2.6 Data analysis 
Data were subjected to repeated measures ANOVA followed by Bonferroni 
mean separation at 5% probability level and all data were analyzed using SAS 
(2004) software. 
 
3 RESULTS AND DISCUSSION 
 
3.1 Results of Pathogenicity tests 
 
Proceedings of 7
th
 International Symposium, SEUSL, 7
th
 & 8
th
 December 2017 
 
242 
 
Alternaria alternata, Cercospora rodmanii, Aspergillus sp. and Trichoderma 
sp. were isolated on PDA from field collected, diseased waterhyacinth. 
Similarly, Surveys for natural enemies of water hyacinth that may be used as 
biological control agents began in 1962 and continued up until recently 
(Center et al., 2001). Many pathogens gave promising results as biological 
control agents of water hyacinth in different countries. Among them are Uredo 
eichhorniae, suitable as a classical biocontrol agent and Acremonium 
zonatum, Alternaria eichhorniae, A. alternata, Cercospora piaropi, 
Myrothecium roridum, and Rhizoctonia solani, which are widely distributed in 
different continents, as bioherbicides. Other less widely distributed pathogens 
include notably species of Bipolaris, Drechslera, and Fusarium, which may 
hold promise, but further studies are needed to confirm their usefulness 
(Charudattan et al., 1985 and Shabana et al., 1995). The changes in leaf area 
affected by the pathogen across intensity levels depend upon inoculation 
method (p=0.003). Further, the leaf area affected depends on the intensity in 
conjunction with the fungal type (p<0.0001). However, the three-way 
interaction between the intensity, inoculation method and the fungal type was 
found to be insignificant at p=0.05 (Table 1). Between subjects effects of 
repeated measures ANOVA revealed that there was no statistically significant 
effect of the inoculation methods on the leaf area affected by the fungal type 
(p=0.06). However, different fungal types had different levels of dead lesions 
formed in the leaf surfaces in water hyacinth. Moreover, inoculation method 
and fungal type do not combine to influence the overall area affected by the 
fungus. 
 
After seven days of inoculation, Alternaria sp. revealed to have the highest 
affected area, followed by Aspergillus sp. and Cercospora sp. (Table 2). 
However, bonferroni mean separation revealed that all four fungal species had 
similar level of effects in term of dead lesion formed in leaves after 22 days of 
inoculation (Table 2). 
 
Table 1. The leaf area affected by the fungal pathogen changes with the intensity. 
     Intensity- Days      Inoculation method- Wounded and Unwounded 
 
Table 2. Mean leaf area affected by fungi after varying days of inoculation. 
 
 
 
Effect category Wilks’ Lambda 
F value p 
Intensity 151.50 <0.0001 
Intensity*Inoculation method 5.00 0.0031 
Intensity*Fungal type 6.34 <0.0001 
Intensity*Inoculation method*Fungal type 1.32 0.2156 
Fungal type Mean leaf area affected (mm
2
) 
D2 D3 D4 D5 D6 D7 D22 
Alternaria sp. 0.61
bc
 4.95
a
 7.94
a
 12.06
a
 18.28
a
 22.34
a
 31.43
a
 
Aspergillus sp. 1.58
ab
 4.24
a
 7.60
a
 9.49
ab
 11.45
b
 14.47
b
 28.70
a
 
Trichoderma sp. 0.31
c
 0.57
b
 1.57
b
 2.12
c
 2.75
c
 3.13
c
 26.12
a
 
Cercospora sp. 2.18
a
 4.30
a
 6.53
a
 8.38
b
 11.46
b
 14.04
b
 25.85
a
 
Proceedings of 7
th
 International Symposium, SEUSL, 7
th
 & 8
th
 December 2017 
 
243 
 
Mean values with same superscript letters in each column are not significantly 
different from each other at α=0.05). 
 
Disease started as small necrotic spots and developed into a leaf blight that 
tended to spread over the leaf. Eventually, these spots enlarge with the 
rounded side facing the petiole and tapering to a narrow point in the direction 
of the laminar tip. Additionally, on the upper surface of the leaves, distinct 
concentric zonation appears giving a target board appearance. The fruiting 
bodies of the fungus are also noticed on the upper surface along these 
concentric rings. Similarly, (Charudattan, 2001) summarized different fungal 
disease symptoms found in association with water hyacinth as zonate leaf 
spot, discrete necrotic foliar spots, necrotic spots and blighting on the leaves. 
 
3.2 Results of Confirmation test   
The same four fungi including A. alternata, Aspergillus sp., Trichoderma sp. 
and C. rodmanii were isolated on PDA from the leaf samples collected from 
first trial and observed diseased symptoms also similar to first pathogenicity 
tests (Figure 1 and Figure 2) which confirmed that the disease syndromes 
were caused by the inoculated pathogenic fungi, not from the other factors. 
 
Repeated measures ANOVA revealed that intensity effect was significant. 
Therefore, there is an effect of time. The results further demonstrated that 
there is a significant effect of fungal types on the leaf area affected by each 
fungus upon inoculation (F=0.002). Moreover, within-subject main effect for 
intensity was also statistically significant (p<0.0001). Interaction between 
fungal type and intensity was also found to be significant at p value of 0.05. 
 
Table 3.  Mean leaf area affected by fungi after varying days of inoculation. 
 
Fungal type 
Mean leaf area affected(mm
2
) 
D2 D3 D4 D5 D6 D7 
Alternaria sp. 
8.09
a
 14.97
a
 19.36
a
 39.67
a
 59.77
a
 72.39
a
 
Aspergillus sp. 
6.91
a
 11.79
a
 13.83
a
 21.81
ab
 27.81
bc
 35.53
bc
 
Trichoderma sp. 
0.00
b
 0.00
b
 2.73
b
 5.03
b
 6.84
c
 9.46
c
 
Cercospora sp. 
5.33
a
 11.94
a
 14.02
a
 28.13
a
 37.66
ab
 48.54
ab
 
Mean values with same superscript letters in each column are not significantly 
different from each other at α=0.05). 
 
The disease symptoms started to appear within 2 days on waterhyacinth 
leaves inoculated with the A. alternata, Aspergillus sp. and C. rodmanii. The 
plants which were inoculated with the Trichoderma sp. started to appear 
disease symptoms after 4 days of inoculation (Table 3). 
Proceedings of 7
th
 International Symposium, SEUSL, 7
th
 & 8
th
 December 2017 
 
244 
 
Within 4days the fungi including A.alternaria, Aspergillus sp. and C.rodmanii 
did not showed significant different on pathogenicity but after 4 days 
A.alternata and C.rodmanii started to appear significant effect than other 2 
fungi. After one week of inoculation A. alternata revealed to have the higher 
affected area followed by C. rodmanii and Aspergillus sp. (Table 3). 
The plants inoculated with the Alternaria alternata dried and undergo 
defoliation within one week and the Trichoderma sp. did not give a significant 
effect on confirmation test. 
 
 
 
 
 
 
 
          (a)                      (b)                    (c)                   (d)                   (e) 
Figure 1. Disease symptoms of first trial on waterhyacinth after one week of 
inoculation. (a) Control plant (b) Infected plant with Alternaria alternata (c) Infected 
plant with Cercospora rodmanii (d) Infected plant with Aspergillus sp. (e) Infected plant 
with Trichoderma sp. 
 
          (a)                      (b)                     (c)                 (d)                       (e) 
Figure 2. Disease symptoms of confirmation test on waterhyacinth after one week of 
inoculation. (a) Control plant (b) Infected plant with Alternaria alternata (c) Infected 
plant with Cercospora rodmanii (d) Infected plant with Aspergillus sp. (e) Infected plant 
with Trichoderma sp. 
Charudattan (2001) reported that Alternaria sp. was highly virulent and 
severely damaged the inoculated water hyacinth leaves. Moreover, the 
potential of A. alternata as biocontrol agent was reported by Abbas et al., 
(1995). 
Some studies confirmed that, studies use of potential fungal pathogens would 
result in reduced water hyacinth biomass (Martyn and Freeman, 1978; 
Charudattan et al., 1985; Shabana et al., 1995). On the other hand, Shabana 
(1997) reported significant physiological changes in water hyacinth infected 
Proceedings of 7
th
 International Symposium, SEUSL, 7
th
 & 8
th
 December 2017 
 
245 
 
with Alternaria sp., such as decrease in pigments, carbohydrates, and relative 
water content which negatively affect the growth and development of the 
weed. Abbas et al. (1995) and Mailu et al. (1998) reported that biological 
control agents (either insects or pathogens) caused disintegration of original 
water hyacinth mats into smaller mats; stunted growth; decline in water 
hyacinth biomass, reduced flowering potential, reduced daughter plants 
production and finally rotting of the petioles followed by sinking. 
 
3.3 Results of mycoherbicide formulation test 
The leaf area affected by the fungal pathogen changes with the intensity (days 
after inoculation). Further, the changes in leaf area affected by the pathogen 
across intensity levels also depend upon the effects of the carrier type used as 
it has an associated p value less than 0.05 (Table 4). However, the leaf area 
affected does not depend on the intensity in conjunction with the fungal type 
(p=0.06). The results showed that there was a significant interaction between 
the intensity, carrier type and fungal type (Table 4).  
Table 4. Within-subjects main effect test for micro-herbicide test. 
Effect category Wilks’ Lambda 
F value P 
Intensity 58.20 <0.0001 
Intensity*Inoculation method 2.07 0.01 
Intensity*Fungal type 2.04 0.06 
Intensity*Inoculation method*Fungal type 1.76 0.01 
 
Between subject effects of repeated measures ANOVA revealed that there 
was a statistically significant effect of the type of carrier used and therefore 
different carriers produced different levels of affected leaf area upon infection 
by the fungal type (p<0.0001). However, fungal types alone did not show 
differences in the formation of dead lesions in the leaf surfaces of water 
hyacinth (p=0.31). Moreover, the carrier type and fungi did not combine to 
influence the overall area affected by the fungus (p=0.49).   
Table 5. Mean leaf area affected by different carrier type for each fungus after varying 
days of inoculation (as revealed by Bonferroni t-tests). 
Carrier type Mean leaf area affected(mm
2
) 
D2 D3 D4 D5 D6 D7 D14 
Corn flour 30% 0.00
c
 0.00
c
 2.30
c
 5.61
c
 8.40
b
 11.36
b
 17.87
b
 
Oven ash 30% 5.18
b
 8.97
b
 13.17
b
 17.49
b
 21.33
b
 27.25
b
 43.94
b
 
Cornflour+Ash30% 0.00
c
 3.08
bc
 5.85
bc
 9.44
bc
 12.99
b
 18.34
b
 35.50
b
 
Corn flour 60% 0.00
c
 2.20b
c
 6.68
bc
 10.63
bc
 14.25
b
 18.70
b
 35.90
b
 
Oven ash 60% 12.70
a
 22.64
a
 34.46
a
 43.63
a
 57.00
a
 71.07
a
 111.94
a
 
Cornflour+Ash60% 3.10b
c
 6.08b
c
 7.98
bc
 11.29
bc
 14.92
b
 18.46
b
 41.63
b
 
Mean values with same superscript letters in each column are not significantly different from 
each other at α=0.05). 
Proceedings of 7
th
 International Symposium, SEUSL, 7
th
 & 8
th
 December 2017 
 
246 
 
The results indicate that oven ash 60% prominently stays significantly different 
from other carrier types contributing appreciably to the lesion formation by 
fungi. This pattern of lesion formation or dead leaves by oven ash 60% found 
to be repeating over the intensity (days after inoculation) (Table 5). Six days 
after inoculation, oven ash 60% produced 57.00 mm2 dead lesion formations, 
which is significantly different from the rest. The other carrier types produced 
lesions in the range of 8.40-21.33 mm2, all of which did not differ from each 
other. Similar pattern was observed after seven and 14 days after inoculation 
though lesion formation was increasing over time (Table 5). The oven ash 
60% produced 111.94 mm2 of dead lesion formation after 14 days of 
inoculation and this stays significantly different from other carrier types after 
the same days of inoculation (Table 5).  Similarly, pathogenicity tests of 
indigenous fungal pathogens on water hyacinth were conducted in different 
countries. Among the identified pathogens A. alternata and C. rodmanii have 
previously been reported (Nag Raj and Ponnappa, 1970; Conway, 1976; 
Abdel Rahim and Tawfig, 1985; Elwakil et al., 1988; Morris, 1990) and they 
are considered as potential mycoherbicide agents for integration in biological 
control of water hyacinth. 
 
CONCLUSIONS  
The attack of the pathogens resulted in killed plants as time progressed and 
higher level of pathogenicity exhibited by A. alternata followed by C. rodmanii 
and Aspergillus sp. In the formulation test, A. alternata and C. rodmanii have 
the best potential to kill water hyacinth. A better and quick infection caused by 
the mycoherbicidal preparation with oven ash and the extent of infection 
depends on the concentration of mycoherbicide and the 60% of oven ash 
concentration showed better result than other mycoherbicide preparations.  
The study suggests that, among the four pathogenic fungi Altrnaria alternata 
and Cercospora rodmanii could be used as effective biocontrol agents against 
water hyacinth following performance evaluation under natural environmental 
conditions and their host specificity test before large scale biological control 
programmes. 
 
REFERENCES 
ABBAS, H.K., DUKE, S.O., PAUL, R.N., RILEY, R.T. and TANAKA, T. (1995) 
AAL-toxin, a potent natural herbicide which disrupts sphingolipid metabolism 
of plants. Pestic. Sci., 43(3): 181-187. 
ABDEL RAHIM, A.M. and TAWFIG, S. (1985) Pathogenicity of Fungi and 
Bacteria from the Sudan to Water hyacinth. Weed Research, (24) 233-238. 
CENTER, T.D., JULIEN, M.H., HILL, M.P. and JIANQING, D. (2001) Biological 
and Integrated Control of Water Hyacinth, Eichhornia crassipes. In: 
Proceedings of the Second Meeting of the Global Working Group for the 
Biological and Integrated Control of Water Hyacinth, Beijing, China, 9–12 
October 2001, 102: 152. 
CHARUDATTAN, R. (2001) Control of water hyacinth by the use of plant 
pathogens, (102) 23-25. 
Proceedings of 7
th
 International Symposium, SEUSL, 7
th
 & 8
th
 December 2017 
 
247 
 
CHARUDATTAN, R. and DINOOR, A. (2000) Biological control of weeds 
using plant pathogens: accomplishments and limitation Crop. Protection. 
CHARUDATTAN, R., KLUEPFEL, B.M., LINDA, S. and OSMAN, Y.A. (1985) 
Biocontrol efficacy of Cercospora rodmanii on water hyacinth. Phytopathology, 
(75) 1263-1269.  
CONWAY, K.E (1976) Evaluation of Cercospora rodmanii as a biological 
control agent of water hyacinth. Phytopathology, (66) 914-917. 
ELWAKIL, M.A., SADIK, E.A., FAYZALLA, E.A. and SHABANA, Y.M. (1988) 
Biological Control of Water hyacinth with Fungal Plant Pathogens in Egypt. In: 
Proc. VII Int. Symp. Biol. Contr. Weeds, 6-11 March 1988, Rome, Italy, 
(Delfosse, E.S ed.). 1st Sper. Patalog. Veg. (MAF) pp 483-497. 
FAO's Plant Production and Protection Division (AGP) 
http://www.fao.org/agriculture/crops/thematic-
sitemap/theme/biodiversity/weeds/issues/sri-ww/en/ accessed on 12.08.2016. 
FIREHUN, Y., TARIKU, G. and ABERA, T. (2006) Water hyacinth status and 
its management at Wonji-Shoa Sugar Factory (Amharic Version). A paper 
presented on the awareness creation workshop on water hyacinth, Ethiopian 
Sugar Industry Research and Training Service. March, 2006. Wonji, pp. 12-18. 
HARRY C. EVANS (1999) Biological control of weed and insect pests using 
fungal pathogens with particular reference to Sri Lanka. Biocontrol news and 
Information, (20) 63N-68N. 
MAILU, A.M., OCHIEL, G.R.S., GITONGA, W. and NJOKA, S.W. (1998) 
Water hyacinth: an environmental disaster in the Winam Gulf of Lake Victoria 
and its control. In: Proc. Ist IOBC Water Hyacinth Working Group 101, Kenya 
Agricultural Research Institute (KARI), Nairobi, Kenya. 
MARTYN, R.D. and FREEMAN, T.E. (1978) Evaluation of Acremonium 
zonatum as a potential biocontrol agent of waterh hyacinth. Plant Dis. Rep., 
62: 604-608. 
MORRIS, M.J. (1990) Cercospora piaropi recorded on the aquatic weed, 
Eichhornia crassipes in South Africa. Phytopathology. (22) 255-256. 
NAG RAJ, T.R. and PONNAPPA, K.M. (1970) Blight of Water hyacinth caused 
by Alternaria eichhornia sp.Nov. Trans. Br. Mycol. Soc. (55) 123-130. 
SHABANA, Y.M. (1997) Vegetable oil suspension emulsions for formulating 
the weed pathogen (Alternaria eichhorniae) to bypass dew. Zeitschrift für 
Pflanzenkrankheiten und Pflanzenschutz, (1040) 239-245. 
SHABANA, Y.M., CHARUDATTAN, R. and ELWAKIL, M.A. (1995) 
Identification of pathogenicity and safety of Alternaria eichhorniae from Egypt 
as a bioherbicide agent for water hyacinth. Biol. Control, (5) 123-135. 
VINCENT, A.C. (2001) Cercospora piaropi and Myrothecium roridum as 
potential bioherbicides to control waterhyacinth, Eichhornia crassipes. Thesis, 
University of Florida, USA.