Agriculture Reference
In-Depth Information
conclusion of issues. All of these issues are just speculations which need to be
verified by further research. Biotypes, metabolites and nitrogen content are
subject for study, which students or researchers can pick.
The population dynamics studies at the study sites indicate that pea aphid
numbers rise in August at the cooler area, an intermediate altitude in the
Ethiopian context, and mostly in September at the warmer area. For optimal
yields planting peas from mid- to late June and at the first week of June at the
warmer place is suggested.
The number of nymphs produced and the survival rate of adult aphids
steadily declined as aphid density per plant increased. Survival and
reproduction was the lowest on faba bean across all levels of aphid density per
plant.
Compared to the untreated control, primicarb and hot pepper treated grass
pea generally had less aphid abundance and had more grain yield. Further
trials on the rate and frequency of application are needed to determine the
cost-effectiveness of treatments alone or in combination with other products
such as soaps or kerosene. Garlic and hot pepper are well known cash crops
grown and it may be unlikely that growers will use these crops for the control
of pea aphids on such marginal crops as grass pea. In the study area, farmers
must grow grass pea in such pea aphid hotspot area every other year for the
sole purpose of crop rotation, otherwise, as farmers know from experience,
their major cereal crops such as wheat and the local staple cereal grain crop,
i.e., teff (
Eragrostis tef
Zucc. Trotter), will fail. Even if there is no grass pea
yield at all due to pea aphids, farmers continue growing it for soil
amelioration. Many farmers also spray insecticides to control pea aphids to be
able to get some yield, though it proved too difficult to stop the aphids even
with frequent sprays.
Because in the host preference study pea aphids occurred more on grass
pea and field pea than on faba bean and lentils, these aphids may be reared on
the better performing plant species when the aphids are needed for some
studies while it would be advisable to avoid cultivating them in areas where
pea aphids are endemic.
R
EFERENCES
Abate, T. 1991. Entomophagous arthropods of Ethiopia: A catalog. Technical
Manual No. 4. Institute of Agricultural Research, Addis Ababa, Ethiopia.
50 PP.
