MSc. Dissertation
Introduction and spread of Parthenium hysterophorus is affecting crop production and
farmer’s health. Impacts of this weed on crop production need be assessed and
effective management measures be developed in order to reduce or prevent its effects.
A study was therefore carried out in Arusha and Meru districts, to (i) describe the
farmer’s perceptions about parthenium weed (ii) establish distribution and abundance
of parthenium weed (iii) assess effective methods for parthenium weed control in
maize fields. To achieve the above mentioned objectives, a field survey was conducted
during the long rain season of 2017 in the study areas where 120 farmers growing
maize and common beans were interviewed. List of villages and farmers were
obtained from the district agricultural officers in the two districts. Three villages from
Meru district (Mbuguni, Nasholi and Mareu) were selected randomly while Ilkerini,
Losikito and Olorieni were randomly selected from Arusha district. Selection of 20
farmers from each village was also done randomly. On distribution and abundance of
the weed, latitudes, longitudes and altitudes were recorded for every 10km intervals
along the main arterial roads leading out of Arusha to Namanga, Kilimanjaro Airport,
Mbuguni and Ilkerini using a hand-held GPS and simultaneously absence or presence
and abundance were recorded. In order to identify effective methods to control the
parthenium weed, a field experiment was carried out in a randomized complete block
design (CRBD) with four replications at the Tropical Pesticides Research Institute
(TPRI) in Arusha. The treatments included hand hoeing twice, dry grass mulch, cover
crop (cowpeas) mulch, application of 2, 4-D twice, weed free and un-weed plot.
Results showed that only 60% of the respondents in Arusha district were aware of the
parthenium weed problem. Forty percent of farmers in Meru district reported to have
known the weed. Overall, occurrence of parthenium weed in both maize and common
bean fields was noted as non-significant. Although farmers reported to have managed
other weeds effectively by hand hoeing, mulching and herbicides application, they
were not actively managing parthenium weed. Few farmers (5.8) reported to have
heard some farmers getting itchiness of hands, arms and legs as they come into contact
with parthenium weed. Habitats, such as roadsides, arable lands, villages and towns
are highly vulnerable to invasion by parthenium weed in Arusha and Meru districts. It
was observed that parthenium weed was highly concentrated on roadsides and along
water tunnels. For instance most (83.08%) farmers in Ilkerini village in Arusha
District confirmed parthenium weed had infested their village. Additionally, 74% of
farmers in Mbuguni village in Meru District also reported the weed to infest their
fields. However few (39.15%) farmers in Olorieni village in Arusha District noticed
the weed to infest their fields. Therefore Arusha municipality was highly infested with
the weed considering its villages and the conducted survey routes being highly
infested with the weed compared with Meru district. For example Ilkerini village and a
road from Arusha Municipal to Namanga had 81% and 79% parthenium weed
coverage respectively. Frequent observation of the weed was observed only in few
areas, for instance along the road from Arusha municipal to Kilimanjaro International
Airport 46% weed coverage was observed after 10km car driving and 42% after 40km
car driving. Water drainage caused 50% weed coverage to be observed in Mbuguni
village in Meru District. In addition, it was noted that road construction works and
drainage water were main agents of disseminating seeds of parthenium weed. Before
the first hand weeding, 2, 4-D application, dry grass mulch and cover crop (cowpea)
hindered parthenium weed growth. Low populations and minimum parthenium heights
were recorded in mulch treated plots. Dry grass and cover crop (cowpeas) mulches
were the best parthenium weed control methods as they reduced parthenium weed
height and population at maize maturity. The control methods did not significantly
affect Maize grain yield (p>0.05). It is concluded that farmers were not aware of the
health hazard caused by parthenium weed in the study areas. Thus proper and targeted
control methods should be employed, especially on roadsides to mitigate the spread of
the weed. Mulching was observed to reduce parthenium weed population; hence
farmers should integrate such method with other control techniques like hand weeding,
biological and chemical control in order to maximize maize and common beans yields.