PESTS AND DISEASES ASSOCIATED WITH
AMARANTH
By
GABRIEL WANYONYI SHIKUKU
REG. A138/10130/2007
SUPERVISOR: DR KIMENJU
INTRODUCTION
• Amaranthus or pigweed, is a cosmopolitan genus of herbs.
• leaves are long-stalked with prominent whitish veins.
• flowers vary depending on species.
• people around world value amaranths as vegetables, cereals and ornamentals.
• Its nutritious leafy vegetable rich in amino acid lysine, vitamins and mineral salts
Introduction cont
• Due richness in macro and micro nutrients
• Its used to address health problems in the
society.
• Integration its grain in the daily diet can
help children recover from malnutrition
1.0 Amaranth Production in
Kenya
• In Kenya, its a minor crop grouped under indigenous vegetable.
• It s grown and consumed in many parts of the country.
• production was mainly localized to Western and Nyanza provinces.
• Production is Kenya is mainly rain fed and subsistence.
its intercropped with main crops or grown on small areas near households.
1.2 Constraints and Future
Prospects of Amaranth
• it is known to contains anti-nutritional factors
such as oxalic acid.
• Small seed size has been documented to pose
limitations in planting, harvesting, threshing and
cleaning.
• Lack of quality seed and technical information .
• Diseases eg Rhizoctonia spp. Phytophthora spp.
Fusarium spp. & Pythium spp
• Pests eg aphids,caterpillars & leaf miners
1.3 Problem of statement and
Justification
• Amaranth represents the largest source of nutrients of all the vegetables and grain.
• Grain and vegetable amaranths have potential to provide many nutritious foods.
• Amaranthus has alleviated problems of malnutrition in developing nations
• Pests and diseases cause reduction on yield and quality of the crop.
• to attain commercial production , there is need to identify and check factors limiting production such as pests and diseases.
1.4 Objectives
• Main objective of this study was to
document the pests and diseases of
amaranth & record the relative proportions
(incidences) with which they occur.
• Specific objective was to establish the role
of weeds in the occurrence of pests and
diseases on Amaranth.
MATERIALS AND METHODS
• Experiment was conducted at the University of
Nairobi farm, Upper Kabete field station.
• Four races {Race 1, Race 2, Race 3 and Race 4] of amaranth seeds were planted in 2x2m plots.
• Experiment was arranged in a split- plot design with Amaranth races as the main plot and weeded/non-weeded treatments as subplots with four replications.
• Disease incidence was scored for using a scale
and diagnosis was done symptomatically
Material $ method cont
• Data on disease incidence was collected weekly.
• For unknown diseases, Kochs postulates was done.
• Data on pest count was collected on five plants tagged randomly.
• Counts on beneficial insects were also done.
• Assessment for pest damage was done by scoring for the number of plants damaged in each treatment.
• Nematode population in soil and root tissue was estimated using Modified Baremann technique .
4.0 RESULTS
• 4.1 Effect of weed on aphids
• Significance Difference along the rows
were observed between the weeded and
non wedded plots (P 0.05).
• aphids population were more in the non
weeded plots in all the races compared to
weeded plots
Table 1.0 Mean aphids population
Races
Weeding No
weeding
R1 2.25 2.56
R2 0.25 0.5
R3 2.25 2.5
R4 3.0 2.75
LSD 0.24
4.2 Effect of weeds on caterpillar
population
• Weeds control had a significance
difference on reduction of caterpillars on
R1,R3.
• No difference on R2 and R5 although
wedding cleared all the caterpillar on R2.
• No difference among the four races
Table 2. Mean of caterpillar count.
Races
Weeding No
weeding
R1 0.25 0.75
R2 0.25 0
R3 0.4 0.75
R4 0.5 0.75
LSD 0.3
4.3 Effect of weed on ladybird
beetle
• Significance difference (P 0.05)was
observed on R3,R4,.
• no effect on lady bird after weeding on R1
and R2.
• there was reduction of ladybird. Table 3.
Table 3. Mean count of lady bird
Races
Weeding No
weeding
R1 6.25 6.30
R2 5.5 6.0
R3 5.0 7.0
R4 6.5 8.0
LSD 1.05
4.4 Effect of weeds on leaf beetle
• Weeding significantly reduced leaf beetle
on amaranth’s especially on R2 (Table 4.).
• There was no significant effect on the
other three races even after weeding.
• Race 2 had highest leaf bettle observed
compared tho other plots with other races.
Table 4 Mean count of leaf bettle before and after weeding
Races
Weeding No
weeding
R1 1.53 1.5
R2 125.93 23.35
R3 0.25 0.48
R4 0.25 0.25
LSD 0.63
4.5 Effect of weed on bacterial
diseases
• Weeding was observed to have
significance effect on bacterial diseases (P
0.05).
• The greatest reduction of diseases was
observed on R3.
• The least ON R2 where there was no
significant difference.
Table 5.0 Mean Bacterial disease score on weeded and non weeded plots.
Races Weeding No
weeding
R1 26.75 22.0
R2 0.25 0.5
R3 26.25 24.7
R4 34.25 30.0
LSD 2.45
4.6 Effect of weeds on viral
diseases
• Viral disease were low during the project period example in R2,R3 & R4.
• There was a significance difference between weeded and non weeded plots in R2.Table 6.
• no significance was observed between the races which may be attributed to the low disease score.
Table 6. Mean viral disease score in weeded and non weeded plot
Races Weeding No
weeding
R1 0.0 0.0
R2 25.0 19.05
R3 0.0 0.0
R4 0.0 0.0
LSD 0.934
Discussion
• Amaranths was found to have many pests and
diseases.
• The experiment result had shown that weeding can reduce the pest population and diseases incidence.
• Reduction of pest population on weeded plots can be explained by the fact that some weeds may harbors pests and can act as alternative crops for pests
• Weeding simple practices can be used to minimizes diseases and pests.
Conclusion .
• Amaranths being an important crops has
shown to be preferred by many pest like
caterpillars, aphids, leaf beetle among
others.
• Bacterial and viral diseases and pest had
shown to be constrain in amaranth us
[production.
Recommendation,
• Weeding had shown to reduce both pest
population and disease incidence.
• Therefore weeding can be recommended
on the Amaranthus production.